keyfork-shard: bump after mnemonic refactor

Note: The type signature of smex::encode and smex::decode has changed,
but will still accept values that were previously passed in.

Cargo.lock

@@ -1674,6 +1674,7 @@ dependencies = [
  "card-backend-pcsc",
  "clap",
  "clap_complete",
+ "keyfork-bin",
  "keyfork-derive-openpgp",
  "keyfork-derive-util",
  "keyfork-entropy",
@@ -1692,6 +1693,13 @@ dependencies = [
  "tokio",
 ]
 
+[[package]]
+name = "keyfork-bin"
+version = "0.1.0"
+dependencies = [
+ "anyhow",
+]
+
 [[package]]
 name = "keyfork-crossterm"
 version = "0.27.1"

Cargo.toml

@@ -14,6 +14,7 @@ members = [
     "crates/qrcode/keyfork-qrcode",
     "crates/qrcode/keyfork-zbar",
     "crates/qrcode/keyfork-zbar-sys",
+    "crates/util/keyfork-bin",
     "crates/util/keyfork-crossterm",
     "crates/util/keyfork-entropy",
     "crates/util/keyfork-frame",

crates/daemon/keyforkd-client/src/lib.rs

@@ -40,6 +40,25 @@
 //! # keyforkd::test_util::Infallible::Ok(())
 //! # }).unwrap();
 //! ```
+//!
+//! In tests, the Keyforkd test_util module and TestPrivateKeys can be used.
+//!
+//! ```rust
+//! use std::str::FromStr;
+//!
+//! use keyforkd_client::Client;
+//! use keyfork_derive_util::DerivationPath;
+//! use keyfork_derive_util::private_key::TestPrivateKey as PrivateKey;
+//!
+//! let seed = b"funky accordion noises";
+//! keyforkd::test_util::run_test(seed, |socket_path| {
+//!     std::env::set_var("KEYFORKD_SOCKET_PATH", socket_path);
+//!     let derivation_path = DerivationPath::from_str("m/44'/0'").unwrap();
+//!     let mut client = Client::discover_socket().unwrap();
+//!     let xprv = client.request_xprv::<PrivateKey>(&derivation_path).unwrap();
+//!     keyforkd::test_util::Infallible::Ok(())
+//! }).unwrap();
+//! ```
 
 pub use std::os::unix::net::UnixStream;
 use std::{collections::HashMap, path::PathBuf};

crates/daemon/keyforkd-client/src/tests.rs

@@ -18,7 +18,7 @@ fn secp256k1_test_suite() {
         let seed = seed_test.seed;
         run_test(&seed, move |socket_path| -> Result<(), Box<dyn std::error::Error + Send>> {
             for test in seed_test.tests {
-                let socket = UnixStream::connect(&socket_path).unwrap();
+                let socket = UnixStream::connect(socket_path).unwrap();
                 let mut client = Client::new(socket);
                 let chain = DerivationPath::from_str(test.chain).unwrap();
                 let chain_len = chain.len();
@@ -29,7 +29,7 @@ fn secp256k1_test_suite() {
                 // key using an XPrv, for all but the last XPrv, which is verified after this
                 for i in 2..chain_len {
                     // FIXME: Keyfork will only allow one request per session
-                    let socket = UnixStream::connect(&socket_path).unwrap();
+                    let socket = UnixStream::connect(socket_path).unwrap();
                     let mut client = Client::new(socket);
                     let path = DerivationPath::from_str(test.chain).unwrap();
                     let left_path = path.inner()[..i]
@@ -40,7 +40,7 @@ fn secp256k1_test_suite() {
                         .fold(DerivationPath::default(), |p, i| p.chain_push(i.clone()));
                     let xprv = dbg!(client.request_xprv::<SecretKey>(&left_path)).unwrap();
                     let derived_xprv = xprv.derive_path(&right_path).unwrap();
-                    let socket = UnixStream::connect(&socket_path).unwrap();
+                    let socket = UnixStream::connect(socket_path).unwrap();
                     let mut client = Client::new(socket);
                     let keyforkd_xprv = client.request_xprv::<SecretKey>(&path).unwrap();
                     assert_eq!(
@@ -73,7 +73,7 @@ fn ed25519_test_suite() {
         let seed = seed_test.seed;
         run_test(&seed, move |socket_path| {
             for test in seed_test.tests {
-                let socket = UnixStream::connect(&socket_path).unwrap();
+                let socket = UnixStream::connect(socket_path).unwrap();
                 let mut client = Client::new(socket);
                 let chain = DerivationPath::from_str(test.chain).unwrap();
                 let chain_len = chain.len();

crates/daemon/keyforkd/README.md

@@ -34,3 +34,15 @@ request, as well as its best-effort guess on what path is being derived (using
 the `keyfork-derive-path-data` crate), to inform the user of what keys are
 requested. Once the server sends the client the new extended private key, the
 client can then choose to use the key as-is, or derive further keys.
+
+## Testing
+
+A Keyfork server can be automatically started by using [`test_util::run_test`].
+The function accepts a closure, starting the server before the closure is run,
+and closing the server after the closure has completed. This may be useful for
+people writing software that interacts with the Keyfork server, such as a
+deriver or a provisioner. A test seed must be provided, but can be any content.
+The closure accepts one argument, the path of the UNIX socket from which the
+server can be accessed.
+
+Examples of the test utility can be seen in the `keyforkd-client` crate.

crates/daemon/keyforkd/src/lib.rs

@@ -57,7 +57,7 @@ pub async fn start_and_run_server_on(
     let service = ServiceBuilder::new()
         .layer(middleware::BincodeLayer::new())
         // TODO: passphrase support and/or store passphrase with mnemonic
-        .service(Keyforkd::new(mnemonic.seed(None)?));
+        .service(Keyforkd::new(mnemonic.generate_seed(None)));
 
     let mut server = match UnixServer::bind(socket_path) {
         Ok(s) => s,

crates/daemon/keyforkd/src/test_util.rs

@@ -25,14 +25,25 @@ pub struct InfallibleError {
 /// ```
 pub type Infallible<T> = std::result::Result<T, InfallibleError>;
 
-/// Run a test making use of a Keyforkd server. The path to the socket of the Keyforkd server is
-/// provided as the only argument to the closure. The closure is expected to return a Result; the
-/// Error field of the Result may be an error returned by a test.
+/// Run a test making use of a Keyforkd server. The test may use a seed (the first argument) from a
+/// test suite, or (as shown in the example below) a simple seed may be used solely to ensure
+/// the server is capable of being interacted with. The test is in the form of a closure, expected
+/// to return a [`Result`] where success is a unit type (test passed) and the error is any error
+/// that happened during the test (alternatively, a panic may be used, and will be returned as an
+/// error).
 ///
 /// # Panics
+/// The function may panic if any errors arise while configuring and using the Tokio multithreaded
+/// runtime.
 ///
-/// The function is not expected to run in production; therefore, the function plays "fast and
-/// loose" wih the usage of [`Result::expect`]. In normal usage, these should never be an issue.
+/// # Examples
+/// ```rust
+/// use std::os::unix::net::UnixStream;
+/// let seed = b"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA";
+/// keyforkd::test_util::run_test(seed.as_slice(), |path| {
+///     UnixStream::connect(&path).map(|_| ())
+/// }).unwrap();
+/// ```
 #[allow(clippy::missing_errors_doc)]
 pub fn run_test<F, E>(seed: &[u8], closure: F) -> Result<(), E>
 where

crates/derive/keyfork-derive-key/src/main.rs

@@ -46,7 +46,7 @@ fn run() -> Result<(), Box<dyn std::error::Error>> {
     let mut client = Client::discover_socket()?;
     let request = DerivationRequest::new(algo, &path);
     let response = client.request(&request.into())?;
-    println!("{}", smex::encode(&DerivationResponse::try_from(response)?.data));
+    println!("{}", smex::encode(DerivationResponse::try_from(response)?.data));
     Ok(())
 }
 

crates/derive/keyfork-derive-openpgp/src/lib.rs

@@ -1,6 +1,9 @@
-//! Creation of OpenPGP certificates from BIP-0032 derived data.
+//! Creation of OpenPGP Transferable Secret Keys from BIP-0032 derived data.
 
-use std::time::{Duration, SystemTime, SystemTimeError};
+use std::{
+    str::FromStr,
+    time::{Duration, SystemTime, SystemTimeError},
+};
 
 use derive_util::{DerivationIndex, ExtendedPrivateKey, IndexError, PrivateKey};
 use ed25519_dalek::SigningKey;
@@ -68,7 +71,24 @@ pub fn derive(xprv: XPrv, keys: &[KeyFlags], userid: &UserID) -> Result<Cert> {
     };
 
     let epoch = SystemTime::UNIX_EPOCH + Duration::from_secs(1);
-    let one_day = SystemTime::now() + Duration::from_secs(60 * 60 * 24);
+    let expiration_date = match std::env::var("KEYFORK_OPENPGP_EXPIRE").as_mut() {
+        Ok(var) => {
+            let ch = var.pop();
+            match (ch, u64::from_str(var)) {
+                (Some(ch @ ('d' | 'm' | 'y')), Ok(expire)) => {
+                    let multiplier = match ch {
+                        'd' => 1,
+                        'm' => 30,
+                        'y' => 365,
+                        _ => unreachable!(),
+                    };
+                    SystemTime::now() + Duration::from_secs(60 * 60 * 24 * expire * multiplier)
+                }
+                _ => SystemTime::now() + Duration::from_secs(60 * 60 * 24),
+            }
+        }
+        Err(_) => SystemTime::now() + Duration::from_secs(60 * 60 * 24),
+    };
 
     // Create certificate with initial key and signature
     let derived_primary_key = xprv.derive_child(&DerivationIndex::new(0, true)?)?;
@@ -80,7 +100,7 @@ pub fn derive(xprv: XPrv, keys: &[KeyFlags], userid: &UserID) -> Result<Cert> {
 
     // Sign and attach primary key and primary userid
     let builder = SignatureBuilder::new(SignatureType::PositiveCertification)
-        .set_key_validity_period(one_day.duration_since(epoch)?)?
+        .set_key_validity_period(expiration_date.duration_since(epoch)?)?
         .set_signature_creation_time(epoch)?
         .set_key_flags(primary_key_flags.clone())?;
     let binding = userid.bind(&mut primary_key.clone().into_keypair()?, &cert, builder)?;
@@ -89,7 +109,8 @@ pub fn derive(xprv: XPrv, keys: &[KeyFlags], userid: &UserID) -> Result<Cert> {
 
     // Set certificate expiration to one day
     let mut keypair = primary_key.clone().into_keypair()?;
-    let signatures = cert.set_expiration_time(&policy, None, &mut keypair, Some(one_day))?;
+    let signatures =
+        cert.set_expiration_time(&policy, None, &mut keypair, Some(expiration_date))?;
     let cert = cert.insert_packets(signatures)?;
 
     let mut cert = cert;
@@ -127,7 +148,7 @@ pub fn derive(xprv: XPrv, keys: &[KeyFlags], userid: &UserID) -> Result<Cert> {
             SignatureBuilder::new(SignatureType::SubkeyBinding)
                 .set_key_flags(subkey_flags.clone())?
                 .set_signature_creation_time(epoch)?
-                .set_key_validity_period(one_day.duration_since(epoch)?)?
+                .set_key_validity_period(expiration_date.duration_since(epoch)?)?
                 .set_embedded_signature(
                     SignatureBuilder::new(SignatureType::PrimaryKeyBinding)
                         .set_signature_creation_time(epoch)?
@@ -141,7 +162,7 @@ pub fn derive(xprv: XPrv, keys: &[KeyFlags], userid: &UserID) -> Result<Cert> {
             SignatureBuilder::new(SignatureType::SubkeyBinding)
                 .set_key_flags(subkey_flags.clone())?
                 .set_signature_creation_time(epoch)?
-                .set_key_validity_period(one_day.duration_since(epoch)?)?
+                .set_key_validity_period(expiration_date.duration_since(epoch)?)?
         };
 
         // Sign subkey with primary key and attach to cert

crates/derive/keyfork-derive-util/src/request.rs

@@ -209,7 +209,7 @@ impl DerivationRequest {
     /// # }
     pub fn derive_with_mnemonic(&self, mnemonic: &Mnemonic) -> Result<DerivationResponse> {
         // TODO: passphrase support and/or store passphrase within mnemonic
-        self.derive_with_master_seed(&mnemonic.seed(None)?)
+        self.derive_with_master_seed(&mnemonic.generate_seed(None))
     }
 
     /// Derive an [`ExtendedPrivateKey`] using the given seed.

crates/derive/keyfork-derive-util/src/tests.rs

@@ -30,7 +30,7 @@ fn secp256k1() {
             } = test;
 
             // Tests for ExtendedPrivateKey
-            let varlen_seed = VariableLengthSeed::new(&seed);
+            let varlen_seed = VariableLengthSeed::new(seed);
             let xkey = ExtendedPrivateKey::<SecretKey>::new(varlen_seed);
             let derived_key = xkey.derive_path(&chain).unwrap();
             assert_eq!(
@@ -51,7 +51,7 @@ fn secp256k1() {
 
             // Tests for DerivationRequest
             let request = DerivationRequest::new(DerivationAlgorithm::Secp256k1, &chain);
-            let response = request.derive_with_master_seed(&seed).unwrap();
+            let response = request.derive_with_master_seed(seed).unwrap();
             assert_eq!(&response.data, private_key.as_slice(), "test: {chain}");
         }
     }
@@ -76,7 +76,7 @@ fn ed25519() {
             } = test;
 
             // Tests for ExtendedPrivateKey
-            let varlen_seed = VariableLengthSeed::new(&seed);
+            let varlen_seed = VariableLengthSeed::new(seed);
             let xkey = ExtendedPrivateKey::<SigningKey>::new(varlen_seed);
             let derived_key = xkey.derive_path(&chain).unwrap();
             assert_eq!(
@@ -97,7 +97,7 @@ fn ed25519() {
 
             // Tests for DerivationRequest
             let request = DerivationRequest::new(DerivationAlgorithm::Ed25519, &chain);
-            let response = request.derive_with_master_seed(&seed).unwrap();
+            let response = request.derive_with_master_seed(seed).unwrap();
             assert_eq!(&response.data, private_key.as_slice(), "test: {chain}");
         }
     }

crates/keyfork-shard/src/bin/keyfork-shard-combine-openpgp.rs

@@ -7,52 +7,33 @@ use std::{
     process::ExitCode,
 };
 
-use keyfork_shard::openpgp::{combine, discover_certs, openpgp::Cert, parse_messages};
+use keyfork_shard::{openpgp::OpenPGP, Format};
 
 type Result<T, E = Box<dyn std::error::Error>> = std::result::Result<T, E>;
 
 fn validate(
     shard: impl AsRef<Path>,
     key_discovery: Option<&str>,
-) -> Result<(File, Vec<Cert>)> {
+) -> Result<(File, Option<PathBuf>)> {
     let key_discovery = key_discovery.map(PathBuf::from);
     key_discovery.as_ref().map(std::fs::metadata).transpose()?;
 
-    // Load certs from path
-    let certs = key_discovery
-        .map(discover_certs)
-        .transpose()?
-        .unwrap_or(vec![]);
-
-    Ok((File::open(shard)?, certs))
+    Ok((File::open(shard)?, key_discovery))
 }
 
 fn run() -> Result<()> {
     let mut args = env::args();
     let program_name = args.next().expect("program name");
     let args = args.collect::<Vec<_>>();
-    let (messages_file, cert_list) = match args.as_slice() {
+    let (messages_file, key_discovery) = match args.as_slice() {
         [shard, key_discovery] => validate(shard, Some(key_discovery))?,
         [shard] => validate(shard, None)?,
         _ => panic!("Usage: {program_name} <shard> [key_discovery]"),
     };
 
-    let mut encrypted_messages = parse_messages(messages_file)?;
-
-    let encrypted_metadata = encrypted_messages
-        .pop_front()
-        .expect("any pgp encrypted message");
-
-    let mut bytes = vec![];
-
-    combine(
-        cert_list,
-        &encrypted_metadata,
-        encrypted_messages.into(),
-        &mut bytes,
-    )?;
-
-    print!("{}", smex::encode(&bytes));
+    let openpgp = OpenPGP;
+    let bytes = openpgp.decrypt_all_shards_to_secret(key_discovery.as_deref(), messages_file)?;
+    print!("{}", smex::encode(bytes));
 
     Ok(())
 }

crates/keyfork-shard/src/bin/keyfork-shard-decrypt-openpgp.rs

@@ -7,47 +7,33 @@ use std::{
     process::ExitCode,
 };
 
-use keyfork_shard::openpgp::{decrypt, discover_certs, openpgp::Cert, parse_messages};
+use keyfork_shard::{Format, openpgp::OpenPGP};
 
 type Result<T, E = Box<dyn std::error::Error>> = std::result::Result<T, E>;
 
-fn validate<'a>(
-    messages_file: impl AsRef<Path>,
-    key_discovery: impl Into<Option<&'a str>>,
-) -> Result<(File, Vec<Cert>)> {
-    let key_discovery = key_discovery.into().map(PathBuf::from);
+fn validate(
+    shard: impl AsRef<Path>,
+    key_discovery: Option<&str>,
+) -> Result<(File, Option<PathBuf>)> {
+    let key_discovery = key_discovery.map(PathBuf::from);
     key_discovery.as_ref().map(std::fs::metadata).transpose()?;
 
-    // Load certs from path
-    let certs = key_discovery
-        .map(discover_certs)
-        .transpose()?
-        .unwrap_or(vec![]);
-
-    Ok((File::open(messages_file)?, certs))
+    Ok((File::open(shard)?, key_discovery))
 }
 
 fn run() -> Result<()> {
     let mut args = env::args();
     let program_name = args.next().expect("program name");
     let args = args.collect::<Vec<_>>();
-    let (messages_file, cert_list) = match args.as_slice() {
-        [messages_file, key_discovery] => validate(messages_file, key_discovery.as_str())?,
-        [messages_file] => validate(messages_file, None)?,
-        _ => panic!("Usage: {program_name} messages_file [key_discovery]"),
+    let (messages_file, key_discovery) = match args.as_slice() {
+        [shard, key_discovery] => validate(shard, Some(key_discovery))?,
+        [shard] => validate(shard, None)?,
+        _ => panic!("Usage: {program_name} <shard> [key_discovery]"),
     };
 
-    let mut encrypted_messages = parse_messages(messages_file)?;
+    let openpgp = OpenPGP;
 
-    let encrypted_metadata = encrypted_messages
-        .pop_front()
-        .expect("any pgp encrypted message");
-
-    decrypt(
-        &cert_list,
-        &encrypted_metadata,
-        encrypted_messages.make_contiguous(),
-    )?;
+    openpgp.decrypt_one_shard_for_transport(key_discovery.as_deref(), messages_file)?;
 
     Ok(())
 }

crates/keyfork-shard/src/bin/keyfork-shard-remote.rs

@@ -20,7 +20,7 @@ fn run() -> Result<()> {
 
     let mut bytes = vec![];
     remote_decrypt(&mut bytes)?;
-    print!("{}", smex::encode(&bytes));
+    print!("{}", smex::encode(bytes));
 
     Ok(())
 }

crates/keyfork-shard/src/bin/keyfork-shard-split-openpgp.rs

@@ -2,14 +2,12 @@
 
 use std::{env, path::PathBuf, process::ExitCode, str::FromStr};
 
-use keyfork_shard::openpgp::{discover_certs, openpgp::Cert, split};
+use keyfork_shard::{Format, openpgp::OpenPGP};
 
 #[derive(Clone, Debug)]
 enum Error {
     Usage(String),
     Input,
-    Threshold(u8, u8),
-    InvalidCertCount(usize, u8),
 }
 
 impl std::fmt::Display for Error {
@@ -19,15 +17,6 @@ impl std::fmt::Display for Error {
                 write!(f, "Usage: {program_name} threshold max key_discovery")
             }
             Error::Input => f.write_str("Expected hex encoded input"),
-            Error::Threshold(threshold, max) => {
-                write!(
-                    f,
-                    "Invalid threshold: 0 < threshold {threshold} <= max {max} < 256"
-                )
-            }
-            Error::InvalidCertCount(count, max) => {
-                write!(f, "Invalid cert count: count {count} != max {max}")
-            }
         }
     }
 }
@@ -36,31 +25,20 @@ impl std::error::Error for Error {}
 
 type Result<T, E = Box<dyn std::error::Error>> = std::result::Result<T, E>;
 
-fn validate(threshold: &str, max: &str, key_discovery: &str) -> Result<(u8, Vec<Cert>)> {
+fn validate(threshold: &str, max: &str, key_discovery: &str) -> Result<(u8, u8, PathBuf)> {
     let threshold = u8::from_str(threshold)?;
     let max = u8::from_str(max)?;
     let key_discovery = PathBuf::from(key_discovery);
-    if threshold > max {
-        return Err(Error::Threshold(threshold, max).into());
-    }
-
-    // Verify path exists
     std::fs::metadata(&key_discovery)?;
 
-    // Load certs from path
-    let certs = discover_certs(key_discovery)?;
-    if certs.len() != max.into() {
-        return Err(Error::InvalidCertCount(certs.len(), max).into());
-    }
-
-    Ok((threshold, certs))
+    Ok((threshold, max, key_discovery))
 }
 
 fn run() -> Result<()> {
     let mut args = env::args();
     let program_name = args.next().expect("program name");
     let args = args.collect::<Vec<_>>();
-    let (threshold, cert_list) = match args.as_slice() {
+    let (threshold, max, key_discovery) = match args.as_slice() {
         [threshold, max, key_discovery] => validate(threshold, max, key_discovery)?,
         _ => return Err(Error::Usage(program_name).into()),
     };
@@ -69,11 +47,12 @@ fn run() -> Result<()> {
         let Some(line) = stdin().lines().next() else {
             return Err(Error::Input.into());
         };
-        smex::decode(&line?)?
+        smex::decode(line?)?
     };
 
-    split(threshold, cert_list, &input, std::io::stdout())?;
+    let openpgp = OpenPGP;
 
+    openpgp.shard_and_encrypt(threshold, max, &input, key_discovery.as_path(), std::io::stdout())?;
     Ok(())
 }
 

crates/keyfork-shard/src/lib.rs

@@ -1,13 +1,13 @@
 #![doc = include_str!("../README.md")]
 
-use std::io::{stdin, stdout, Write};
+use std::io::{stdin, stdout, Read, Write};
 
 use aes_gcm::{
-    aead::{Aead, AeadCore, OsRng},
-    Aes256Gcm, KeyInit,
+    aead::{consts::U12, Aead, AeadCore, OsRng},
+    Aes256Gcm, KeyInit, Nonce,
 };
 use hkdf::Hkdf;
-use keyfork_mnemonic_util::{Mnemonic, Wordlist};
+use keyfork_mnemonic_util::{English, Mnemonic};
 use keyfork_prompt::{
     validators::{mnemonic::MnemonicSetValidator, Validator},
     Message as PromptMessage, PromptHandler, Terminal,
@@ -16,9 +16,338 @@ use sha2::Sha256;
 use sharks::{Share, Sharks};
 use x25519_dalek::{EphemeralSecret, PublicKey};
 
+// 256 bit share encrypted is 49 bytes, couple more bytes before we reach max size
+const ENC_LEN: u8 = 4 * 16;
+
 #[cfg(feature = "openpgp")]
 pub mod openpgp;
 
+/// A trait to specify where keys can be discovered from, such as a Rust-native type or a path on
+/// the filesystem that keys may be read from.
+pub trait KeyDiscovery<F: Format + ?Sized> {
+    /// Discover public keys for the associated format.
+    ///
+    /// # Errors
+    /// The method may return an error if public keys could not be loaded from the given discovery
+    /// mechanism. A discovery mechanism _must_ be able to detect public keys.
+    fn discover_public_keys(&self) -> Result<Vec<F::PublicKey>, F::Error>;
+
+    /// Discover private keys for the associated format.
+    ///
+    /// # Errors
+    /// The method may return an error if private keys could not be loaded from the given
+    /// discovery mechanism. Keys may exist off-system (such as with smartcards), in which case the
+    /// PrivateKeyData type of the asssociated format should be either `()` (if the keys may never
+    /// exist on-system) or an empty container (such as an empty Vec); in either case, this method
+    /// _must not_ return an error if keys are accessible but can't be transferred into memory.
+    fn discover_private_keys(&self) -> Result<F::PrivateKeyData, F::Error>;
+}
+
+/// A format to use for splitting and combining secrets.
+pub trait Format {
+    /// The error type returned from any failed operations.
+    type Error: std::error::Error + 'static;
+
+    /// A type encapsulating a single public key recipient.
+    type PublicKey;
+
+    /// A type encapsulating the private key recipients of shards.
+    type PrivateKeyData;
+
+    /// A type representing a Signer derived from the secret.
+    type SigningKey;
+
+    /// A type representing the parsed, but encrypted, Shard data.
+    type EncryptedData;
+
+    /// Derive a signer
+    fn derive_signing_key(&self, seed: &[u8]) -> Self::SigningKey;
+
+    /// Format a header containing necessary metadata. Such metadata contains a version byte, a
+    /// threshold byte, a public version of the [`Format::SigningKey`], and the public keys used to
+    /// encrypt shards. The public keys must be kept _in order_ to the encrypted shards. Keyfork
+    /// will use the same key_data for both, ensuring an iteration of this method will match with
+    /// iterations in methods called later.
+    ///
+    /// # Errors
+    /// The method may return an error if encryption to any of the public keys fails.
+    fn format_encrypted_header(
+        &self,
+        signing_key: &Self::SigningKey,
+        key_data: &[Self::PublicKey],
+        threshold: u8,
+    ) -> Result<Self::EncryptedData, Self::Error>;
+
+    /// Format a shard encrypted to the given public key, signing with the private key.
+    ///
+    /// # Errors
+    /// The method may return an error if the public key used to encrypt the shard is unsuitable
+    /// for encryption, or if an error occurs while encrypting.
+    fn encrypt_shard(
+        &self,
+        shard: &[u8],
+        public_key: &Self::PublicKey,
+        signing_key: &mut Self::SigningKey,
+    ) -> Result<Self::EncryptedData, Self::Error>;
+
+    /// Parse the Shard file into a processable type.
+    ///
+    /// # Errors
+    /// The method may return an error if the Shard file could not be read from or if the Shard
+    /// file could not be properly parsed.
+    fn parse_shard_file(
+        &self,
+        shard_file: impl Read + Send + Sync,
+    ) -> Result<Vec<Self::EncryptedData>, Self::Error>;
+
+    /// Write the Shard data to a Shard file.
+    ///
+    /// # Errors
+    /// The method may return an error if the Shard data could not be properly serialized or if the
+    /// Shard file could not be written to.
+    fn format_shard_file(
+        &self,
+        encrypted_data: &[Self::EncryptedData],
+        shard_file: impl Write + Send + Sync,
+    ) -> Result<(), Self::Error>;
+
+    /// Decrypt shares and associated metadata from a readable input. For the current version of
+    /// Keyfork, the only associated metadata is a u8 representing the threshold to combine
+    /// secrets.
+    ///
+    /// # Errors
+    /// The method may return an error if the shardfile couldn't be read from, if all shards
+    /// could not be decrypted, or if a shard could not be parsed from the decrypted data.
+    fn decrypt_all_shards(
+        &self,
+        private_keys: Option<Self::PrivateKeyData>,
+        encrypted_messages: &[Self::EncryptedData],
+    ) -> Result<(Vec<Share>, u8), Self::Error>;
+
+    /// Decrypt a single share and associated metadata from a reaable input. For the current
+    /// version of Keyfork, the only associated metadata is a u8 representing the threshold to
+    /// combine secrets.
+    ///
+    /// # Errors
+    /// The method may return an error if the shardfile couldn't be read from, if a shard could not
+    /// be decrypted, or if a shard could not be parsed from the decrypted data.
+    fn decrypt_one_shard(
+        &self,
+        private_keys: Option<Self::PrivateKeyData>,
+        encrypted_data: &[Self::EncryptedData],
+    ) -> Result<(Share, u8), Self::Error>;
+
+    /// Decrypt multiple shares and combine them to recreate a secret.
+    ///
+    /// # Errors
+    /// The method may return an error if the shares can't be decrypted or if the shares can't
+    /// be combined into a secret.
+    fn decrypt_all_shards_to_secret(
+        &self,
+        private_key_discovery: Option<impl KeyDiscovery<Self>>,
+        reader: impl Read + Send + Sync,
+    ) -> Result<Vec<u8>, Box<dyn std::error::Error>> {
+        let private_keys = private_key_discovery
+            .map(|p| p.discover_private_keys())
+            .transpose()?;
+        let encrypted_messages = self.parse_shard_file(reader)?;
+        let (shares, threshold) = self.decrypt_all_shards(private_keys, &encrypted_messages)?;
+
+        let secret = Sharks(threshold)
+            .recover(&shares)
+            .map_err(|e| SharksError::CombineShare(e.to_string()))?;
+
+        Ok(secret)
+    }
+
+    /// Establish an AES-256-GCM transport key using ECDH, decrypt a single shard, and encrypt the
+    /// shard to the AES key.
+    ///
+    /// # Errors
+    /// The method may return an error if a share can't be decrypted. The method will not return an
+    /// error if the camera is inaccessible or if a hardware error is encountered while scanning a
+    /// QR code; instead, a mnemonic prompt will be used.
+    fn decrypt_one_shard_for_transport(
+        &self,
+        private_key_discovery: Option<impl KeyDiscovery<Self>>,
+        reader: impl Read + Send + Sync,
+    ) -> Result<(), Box<dyn std::error::Error>> {
+        let mut pm = Terminal::new(stdin(), stdout())?;
+
+        // parse input
+        let private_keys = private_key_discovery
+            .map(|p| p.discover_private_keys())
+            .transpose()?;
+        let encrypted_messages = self.parse_shard_file(reader)?;
+
+        // establish AES-256-GCM key via ECDH
+        let mut nonce_data: Option<[u8; 12]> = None;
+        let mut pubkey_data: Option<[u8; 32]> = None;
+
+        // receive remote data via scanning QR code from camera
+        #[cfg(feature = "qrcode")]
+        {
+            pm.prompt_message(PromptMessage::Text(QRCODE_PROMPT.to_string()))?;
+            if let Ok(Some(hex)) =
+                keyfork_qrcode::scan_camera(std::time::Duration::from_secs(30), 0)
+            {
+                let decoded_data = smex::decode(&hex)?;
+                nonce_data = Some(decoded_data[..12].try_into().map_err(|_| InvalidData)?);
+                pubkey_data = Some(decoded_data[12..].try_into().map_err(|_| InvalidData)?)
+            } else {
+                pm.prompt_message(PromptMessage::Text(QRCODE_ERROR.to_string()))?;
+            };
+        }
+
+        // if QR code scanning failed or was unavailable, read from a set of mnemonics
+        let (nonce, their_pubkey) = match (nonce_data, pubkey_data) {
+            (Some(nonce), Some(pubkey)) => (nonce, pubkey),
+            _ => {
+                let validator = MnemonicSetValidator {
+                    word_lengths: [9, 24],
+                };
+                let [nonce_mnemonic, pubkey_mnemonic] = pm
+                    .prompt_validated_wordlist::<English, _>(
+                        QRCODE_COULDNT_READ,
+                        3,
+                        validator.to_fn(),
+                    )?;
+
+                let nonce = nonce_mnemonic
+                    .as_bytes()
+                    .try_into()
+                    .map_err(|_| InvalidData)?;
+                let pubkey = pubkey_mnemonic
+                    .as_bytes()
+                    .try_into()
+                    .map_err(|_| InvalidData)?;
+                (nonce, pubkey)
+            }
+        };
+
+        // create our shared key
+        let our_key = EphemeralSecret::random();
+        let our_pubkey_mnemonic = Mnemonic::from_bytes(PublicKey::from(&our_key).as_bytes())?;
+        let shared_secret = our_key
+            .diffie_hellman(&PublicKey::from(their_pubkey))
+            .to_bytes();
+        let hkdf = Hkdf::<Sha256>::new(None, &shared_secret);
+        let mut hkdf_output = [0u8; 256 / 8];
+        hkdf.expand(&[], &mut hkdf_output)?;
+        let shared_key = Aes256Gcm::new_from_slice(&hkdf_output)?;
+
+        // decrypt a single shard and create the payload
+        let (share, threshold) = self.decrypt_one_shard(private_keys, &encrypted_messages)?;
+        let mut payload = Vec::from(&share);
+        payload.insert(0, HUNK_VERSION);
+        payload.insert(1, threshold);
+        assert!(
+            payload.len() <= ENC_LEN as usize,
+            "invalid share length (too long, max {ENC_LEN} bytes)"
+        );
+
+        // encrypt data
+        let nonce = Nonce::<U12>::from_slice(&nonce);
+        let payload_bytes = shared_key.encrypt(nonce, payload.as_slice())?;
+
+        // convert data to a static-size payload
+        // NOTE: Padding length is less than u8::MAX because ENC_LEN < u8::MAX
+        #[allow(clippy::assertions_on_constants)]
+        {
+            assert!(ENC_LEN < u8::MAX, "padding byte can be u8");
+        }
+        #[allow(clippy::cast_possible_truncation)]
+        let mut out_bytes = [payload_bytes.len() as u8; ENC_LEN as usize];
+        assert!(
+            payload_bytes.len() < out_bytes.len(),
+            "encrypted payload larger than acceptable limit"
+        );
+        out_bytes[..payload_bytes.len()].clone_from_slice(&payload_bytes);
+
+        // NOTE: This previously used a single repeated value as the padding byte, but resulted in
+        // difficulty when entering in prompts manually, as one's place could be lost due to
+        // repeated keywords. This is resolved below by having sequentially increasing numbers up to
+        // but not including the last byte.
+        #[allow(clippy::cast_possible_truncation)]
+        for (i, byte) in (out_bytes[payload_bytes.len()..(ENC_LEN as usize - 1)])
+            .iter_mut()
+            .enumerate()
+        {
+            *byte = (i % u8::MAX as usize) as u8;
+        }
+
+        // safety: size of out_bytes is constant and always % 4 == 0
+        let payload_mnemonic = unsafe { Mnemonic::from_raw_bytes(&out_bytes) };
+
+        #[cfg(feature = "qrcode")]
+        {
+            use keyfork_qrcode::{qrencode, ErrorCorrection};
+            let mut qrcode_data = our_pubkey_mnemonic.to_bytes();
+            qrcode_data.extend(payload_mnemonic.as_bytes());
+            if let Ok(qrcode) = qrencode(&smex::encode(&qrcode_data), ErrorCorrection::Highest) {
+                pm.prompt_message(PromptMessage::Text(
+                    concat!(
+                        "A QR code will be displayed after this prompt. ",
+                        "Send the QR code back to the operator combining the shards. ",
+                        "Nobody else should scan this QR code."
+                    )
+                    .to_string(),
+                ))?;
+                pm.prompt_message(PromptMessage::Data(qrcode))?;
+            }
+        }
+
+        pm.prompt_message(PromptMessage::Text(format!(
+            "Upon request, these words should be sent: {our_pubkey_mnemonic} {payload_mnemonic}"
+        )))?;
+
+        Ok(())
+    }
+
+    /// Split a secret into a shard for every shard in keys, with the given Shamir's Secret Sharing
+    /// threshold.
+    ///
+    /// # Errors
+    /// The method may return an error if the shares can't be encrypted.
+    fn shard_and_encrypt(
+        &self,
+        threshold: u8,
+        max: u8,
+        secret: &[u8],
+        public_key_discovery: impl KeyDiscovery<Self>,
+        writer: impl Write + Send + Sync,
+    ) -> Result<(), Box<dyn std::error::Error>> {
+        let mut signing_key = self.derive_signing_key(secret);
+
+        let sharks = Sharks(threshold);
+        let dealer = sharks.dealer(secret);
+
+        let public_keys = public_key_discovery.discover_public_keys()?;
+        assert!(
+            public_keys.len() < u8::MAX as usize,
+            "must have less than u8::MAX public keys"
+        );
+        assert_eq!(
+            max,
+            public_keys.len() as u8,
+            "max must be equal to amount of public keys"
+        );
+        let max = public_keys.len() as u8;
+        assert!(max >= threshold, "threshold must not exceed max keys");
+
+        let header = self.format_encrypted_header(&signing_key, &public_keys, threshold)?;
+        let mut messages = vec![header];
+        for (pk, share) in public_keys.iter().zip(dealer) {
+            let shard = Vec::from(&share);
+            messages.push(self.encrypt_shard(&shard, pk, &mut signing_key)?);
+        }
+
+        self.format_shard_file(&messages, writer)?;
+
+        Ok(())
+    }
+}
+
 /// Errors encountered while creating or combining shares using Shamir's Secret Sharing.
 #[derive(thiserror::Error, Debug)]
 pub enum SharksError {
@@ -63,7 +392,6 @@ const QRCODE_ERROR: &str = "Unable to scan a QR code. Falling back to text entry
 /// incompatible with the currently running version.
 pub fn remote_decrypt(w: &mut impl Write) -> Result<(), Box<dyn std::error::Error>> {
     let mut pm = Terminal::new(stdin(), stdout())?;
-    let wordlist = Wordlist::default();
 
     let mut iter_count = None;
     let mut shares = vec![];
@@ -74,11 +402,9 @@ pub fn remote_decrypt(w: &mut impl Write) -> Result<(), Box<dyn std::error::Erro
     while iter_count.is_none() || iter_count.is_some_and(|i| i > 0) {
         iter += 1;
         let nonce = Aes256Gcm::generate_nonce(&mut OsRng);
-        let nonce_mnemonic =
-            unsafe { Mnemonic::from_raw_entropy(nonce.as_slice(), Default::default()) };
+        let nonce_mnemonic = unsafe { Mnemonic::from_raw_bytes(nonce.as_slice()) };
         let our_key = EphemeralSecret::random();
-        let key_mnemonic =
-            Mnemonic::from_entropy(PublicKey::from(&our_key).as_bytes(), Default::default())?;
+        let key_mnemonic = Mnemonic::from_bytes(PublicKey::from(&our_key).as_bytes())?;
 
         #[cfg(feature = "qrcode")]
         {
@@ -132,12 +458,12 @@ pub fn remote_decrypt(w: &mut impl Write) -> Result<(), Box<dyn std::error::Erro
                     word_lengths: [24, 48],
                 };
 
-                let [pubkey_mnemonic, payload_mnemonic] = pm.prompt_validated_wordlist(
-                    QRCODE_COULDNT_READ,
-                    &wordlist,
-                    3,
-                    validator.to_fn(),
-                )?;
+                let [pubkey_mnemonic, payload_mnemonic] = pm
+                    .prompt_validated_wordlist::<English, _>(
+                        QRCODE_COULDNT_READ,
+                        3,
+                        validator.to_fn(),
+                    )?;
                 let pubkey = pubkey_mnemonic
                     .as_bytes()
                     .try_into()

crates/keyfork-shard/src/openpgp.rs

@@ -17,7 +17,7 @@ use keyfork_derive_openpgp::{
     derive_util::{DerivationPath, PathError, VariableLengthSeed},
     XPrv,
 };
-use keyfork_mnemonic_util::{Mnemonic, MnemonicFromStrError, MnemonicGenerationError, Wordlist};
+use keyfork_mnemonic_util::{English, Mnemonic, MnemonicFromStrError, MnemonicGenerationError};
 use keyfork_prompt::{
     validators::{mnemonic::MnemonicSetValidator, Validator},
     Error as PromptError, Message as PromptMessage, PromptHandler, Terminal,
@@ -57,8 +57,8 @@ const SHARD_METADATA_VERSION: u8 = 1;
 const SHARD_METADATA_OFFSET: usize = 2;
 
 use super::{
-    InvalidData, SharksError, HUNK_VERSION, QRCODE_COULDNT_READ, QRCODE_ERROR, QRCODE_PROMPT,
-    QRCODE_TIMEOUT,
+    Format, InvalidData, SharksError, HUNK_VERSION, QRCODE_COULDNT_READ, QRCODE_ERROR,
+    QRCODE_PROMPT, QRCODE_TIMEOUT, KeyDiscovery
 };
 
 // 256 bit share is 49 bytes + some amount of hunk bytes, gives us reasonable padding
@@ -163,6 +163,55 @@ impl EncryptedMessage {
         }
     }
 
+    /// Parse OpenPGP packets for encrypted messages.
+    pub fn from_reader(input: impl Read + Send + Sync) -> openpgp::Result<Vec<Self>> {
+        let mut pkesks = Vec::new();
+        let mut encrypted_messages = vec![];
+
+        for packet in PacketPile::from_reader(input)
+            .map_err(Error::Sequoia)?
+            .into_children()
+        {
+            match packet {
+                Packet::PKESK(p) => pkesks.push(p),
+                Packet::SEIP(s) => {
+                    encrypted_messages.push(EncryptedMessage::new(&mut pkesks, s));
+                }
+                s => {
+                    panic!("Invalid variant found: {}", s.tag());
+                }
+            }
+        }
+
+        Ok(encrypted_messages)
+    }
+
+    /// Serialize all contents of the message to a writer.
+    ///
+    /// # Errors
+    /// The function may error for any condition in Sequoia's Serialize trait.
+    fn serialize(&self, mut o: impl std::io::Write + Send + Sync) -> openpgp::Result<()> {
+        for pkesk in &self.pkesks {
+            let mut packet = vec![];
+            pkesk.serialize(&mut packet).map_err(Error::Sequoia)?;
+            let message = Message::new(&mut o);
+            let mut message = ArbitraryWriter::new(message, Tag::PKESK).map_err(Error::Sequoia)?;
+            message.write_all(&packet).map_err(Error::SequoiaIo)?;
+            message.finalize().map_err(Error::Sequoia)?;
+        }
+        let mut packet = vec![];
+        self.message
+            .serialize(&mut packet)
+            .map_err(Error::Sequoia)?;
+
+        let message = Message::new(&mut o);
+        let mut message = ArbitraryWriter::new(message, Tag::SEIP).map_err(Error::Sequoia)?;
+        message.write_all(&packet).map_err(Error::SequoiaIo)?;
+        message.finalize().map_err(Error::Sequoia)?;
+
+        Ok(())
+    }
+
     /// Decrypt the message with a Sequoia policy and decryptor.
     ///
     /// This method creates a container containing the packets and passes the serialized container
@@ -176,23 +225,8 @@ impl EncryptedMessage {
         H: VerificationHelper + DecryptionHelper,
     {
         let mut packets = vec![];
-
-        for pkesk in &self.pkesks {
-            let mut packet = vec![];
-            pkesk.serialize(&mut packet).map_err(Error::Sequoia)?;
-            let message = Message::new(&mut packets);
-            let mut message = ArbitraryWriter::new(message, Tag::PKESK).map_err(Error::Sequoia)?;
-            message.write_all(&packet).map_err(Error::SequoiaIo)?;
-            message.finalize().map_err(Error::Sequoia)?;
-        }
-        let mut packet = vec![];
-        self.message
-            .serialize(&mut packet)
+        self.serialize(&mut packets)
             .map_err(Error::Sequoia)?;
-        let message = Message::new(&mut packets);
-        let mut message = ArbitraryWriter::new(message, Tag::SEIP).map_err(Error::Sequoia)?;
-        message.write_all(&packet).map_err(Error::SequoiaIo)?;
-        message.finalize().map_err(Error::Sequoia)?;
 
         let mut decryptor = DecryptorBuilder::from_bytes(&packets)
             .map_err(Error::Sequoia)?
@@ -207,12 +241,357 @@ impl EncryptedMessage {
     }
 }
 
+///
+pub struct OpenPGP;
+
+impl OpenPGP {
+    /// Read all OpenPGP certificates in a path and return a [`Vec`] of them. Certificates are read
+    /// from a file, or from files one level deep in a directory.
+    ///
+    /// # Errors
+    /// The function may return an error if it is unable to read the directory or if Sequoia is unable
+    /// to load certificates from the file.
+    pub fn discover_certs(path: impl AsRef<Path>) -> Result<Vec<Cert>> {
+        let path = path.as_ref();
+
+        if path.is_file() {
+            let mut vec = vec![];
+            for cert in CertParser::from_file(path).map_err(Error::Sequoia)? {
+                vec.push(cert.map_err(Error::Sequoia)?);
+            }
+            Ok(vec)
+        } else {
+            let mut vec = vec![];
+            for entry in path
+                .read_dir()
+                .map_err(Error::Io)?
+                .filter_map(Result::ok)
+                .filter(|p| p.path().is_file())
+            {
+                vec.push(Cert::from_file(entry.path()).map_err(Error::Sequoia)?);
+            }
+            Ok(vec)
+        }
+    }
+}
+
+impl Format for OpenPGP {
+    type Error = Error;
+    type PublicKey = Cert;
+    type PrivateKeyData = Vec<Cert>;
+    type SigningKey = Cert;
+    type EncryptedData = EncryptedMessage;
+
+    /// Derive an OpenPGP Shard certificate from the given seed.
+    fn derive_signing_key(&self, seed: &[u8]) -> Self::SigningKey {
+        let seed = VariableLengthSeed::new(seed);
+        // build cert to sign encrypted shares
+        let userid = UserID::from("keyfork-sss");
+        let path = DerivationPath::from_str("m/7366512'/0'").expect("valid derivation path");
+        let xprv = XPrv::new(seed)
+            .derive_path(&path)
+            .expect("valid derivation");
+        keyfork_derive_openpgp::derive(
+            xprv,
+            &[KeyFlags::empty().set_certification().set_signing()],
+            &userid,
+        )
+        .expect("valid cert creation")
+    }
+
+    fn format_encrypted_header(
+        &self,
+        signing_key: &Self::SigningKey,
+        key_data: &[Self::PublicKey],
+        threshold: u8,
+    ) -> Result<Self::EncryptedData, Self::Error> {
+        let policy = StandardPolicy::new();
+        let mut pp = vec![SHARD_METADATA_VERSION, threshold];
+        // Note: Sequoia does not export private keys on a Cert, only on a TSK
+        signing_key
+            .serialize(&mut pp)
+            .expect("serialize cert into bytes");
+        for cert in key_data {
+            cert.serialize(&mut pp)
+                .expect("serialize pubkey into bytes");
+        }
+
+        // verify packet pile
+        let mut iter = openpgp::cert::CertParser::from_bytes(&pp[SHARD_METADATA_OFFSET..])
+            .expect("should have certs");
+        let first_cert = iter.next().transpose().ok().flatten().expect("first cert");
+        assert_eq!(signing_key, &first_cert);
+
+        for (packet_cert, cert) in iter.zip(key_data) {
+            assert_eq!(
+                &packet_cert.expect("parsed packet cert"),
+                cert,
+                "packet pile could not recreate cert: {}",
+                cert.fingerprint(),
+            );
+        }
+
+        let valid_certs = key_data
+            .iter()
+            .map(|c| c.with_policy(&policy, None))
+            .collect::<openpgp::Result<Vec<_>>>()
+            .map_err(Error::Sequoia)?;
+        let recipients = valid_certs.iter().flat_map(|vc| {
+            get_encryption_keys(vc).map(|key| Recipient::new(KeyID::wildcard(), key.key()))
+        });
+
+        // Process is as follows:
+        // * Any OpenPGP message
+        // * An encrypted message
+        // * A literal message
+        // * The packet pile
+        //
+        // When decrypting, OpenPGP will see:
+        // * A message, and parse it
+        // * An encrypted message, and decrypt it
+        // * A literal message, and extract it
+        // * The packet pile
+        let mut output = vec![];
+        let message = Message::new(&mut output);
+        let encrypted_message = Encryptor2::for_recipients(message, recipients)
+            .build()
+            .map_err(Error::Sequoia)?;
+        let mut literal_message = LiteralWriter::new(encrypted_message)
+            .build()
+            .map_err(Error::Sequoia)?;
+        literal_message.write_all(&pp).map_err(Error::SequoiaIo)?;
+        literal_message.finalize().map_err(Error::Sequoia)?;
+
+        // Parse it into an EncryptedMessage. Yes, this takes a serialized message
+        // and deserializes it. Don't think about it too hard. It's easier this way.
+
+        let mut pkesks = vec![];
+        for packet in PacketPile::from_reader(output.as_slice())
+            .map_err(Error::Sequoia)?
+            .into_children()
+        {
+            match packet {
+                Packet::PKESK(p) => pkesks.push(p),
+                Packet::SEIP(s) => return Ok(EncryptedMessage::new(&mut pkesks, s)),
+                s => panic!("Invalid variant found: {}", s.tag()),
+            }
+        }
+
+        panic!("Unable to build EncryptedMessage from PacketPile");
+    }
+
+    fn encrypt_shard(
+        &self,
+        shard: &[u8],
+        public_key: &Cert,
+        signing_key: &mut Self::SigningKey,
+    ) -> Result<EncryptedMessage> {
+        let policy = StandardPolicy::new();
+        let valid_cert = public_key
+            .with_policy(&policy, None)
+            .map_err(Error::Sequoia)?;
+        let encryption_keys = get_encryption_keys(&valid_cert).collect::<Vec<_>>();
+
+        let signing_key = signing_key
+            .primary_key()
+            .parts_into_secret()
+            .map_err(Error::Sequoia)?
+            .key()
+            .clone()
+            .into_keypair()
+            .map_err(Error::Sequoia)?;
+
+        // Process is as follows:
+        // * Any OpenPGP message
+        // * An encrypted message
+        // * A signed message
+        // * A literal message
+        // * The shard itself
+        //
+        // When decrypting, OpenPGP will see:
+        // * A message, and parse it
+        // * An encrypted message, and decrypt it
+        // * A signed message, and verify it
+        // * A literal message, and extract it
+        // * The shard itself
+        let mut message_output = vec![];
+        let message = Message::new(&mut message_output);
+        let encrypted_message = Encryptor2::for_recipients(
+            message,
+            encryption_keys
+                .iter()
+                .map(|k| Recipient::new(KeyID::wildcard(), k.key())),
+        )
+        .build()
+        .map_err(Error::Sequoia)?;
+        let signed_message = Signer::new(encrypted_message, signing_key)
+            .build()
+            .map_err(Error::Sequoia)?;
+        let mut message = LiteralWriter::new(signed_message)
+            .build()
+            .map_err(Error::Sequoia)?;
+        message.write_all(shard).map_err(Error::SequoiaIo)?;
+        message.finalize().map_err(Error::Sequoia)?;
+
+        let message = EncryptedMessage::from_reader(message_output.as_slice())
+            .map_err(Error::Sequoia)?
+            .into_iter()
+            .next()
+            .expect("serialized message should be parseable");
+
+        Ok(message)
+    }
+
+    fn parse_shard_file(
+        &self,
+        shard_file: impl Read + Send + Sync,
+    ) -> Result<Vec<Self::EncryptedData>, Self::Error> {
+        EncryptedMessage::from_reader(shard_file).map_err(Error::Sequoia)
+    }
+
+    fn format_shard_file(
+        &self,
+        encrypted_data: &[Self::EncryptedData],
+        shard_file: impl Write + Send + Sync,
+    ) -> Result<(), Self::Error> {
+        let mut writer = Writer::new(shard_file, Kind::Message).map_err(Error::SequoiaIo)?;
+        for message in encrypted_data {
+            message.serialize(&mut writer).map_err(Error::Sequoia)?;
+        }
+        writer.finalize().map_err(Error::SequoiaIo)?;
+        Ok(())
+    }
+
+    fn decrypt_all_shards(
+        &self,
+        private_keys: Option<Self::PrivateKeyData>,
+        encrypted_data: &[Self::EncryptedData],
+    ) -> std::result::Result<(Vec<Share>, u8), Self::Error> {
+        // Be as liberal as possible when decrypting.
+        // We don't want to invalidate someone's keys just because the old sig expired.
+        let policy = NullPolicy::new();
+        let mut keyring = Keyring::new(private_keys.unwrap_or_default())?;
+        let mut manager = SmartcardManager::new()?;
+
+        let mut encrypted_messages = encrypted_data.iter();
+
+        let metadata = encrypted_messages.next().expect("metdata");
+        let metadata_content = decrypt_metadata(metadata, &policy, &mut keyring, &mut manager)?;
+
+        let (threshold, root_cert, certs) = decode_metadata_v1(&metadata_content)?;
+
+        keyring.set_root_cert(root_cert.clone());
+        manager.set_root_cert(root_cert.clone());
+
+        // Generate a controlled binding from certificates to encrypted messages. This is stable
+        // because we control the order packets are encrypted and certificates are stored.
+
+        // TODO: remove alloc, convert EncryptedMessage to &EncryptedMessage
+        let mut messages: HashMap<KeyID, EncryptedMessage> = certs
+            .iter()
+            .map(Cert::keyid)
+            .zip(encrypted_messages.cloned())
+            .collect();
+        let mut decrypted_messages =
+            decrypt_with_keyring(&mut messages, &certs, &policy, &mut keyring)?;
+
+        // clean decrypted messages from encrypted messages
+        messages.retain(|k, _v| !decrypted_messages.contains_key(k));
+
+        let left_from_threshold = threshold as usize - decrypted_messages.len();
+        if left_from_threshold > 0 {
+            #[allow(clippy::cast_possible_truncation)]
+            let new_messages = decrypt_with_manager(
+                left_from_threshold as u8,
+                &mut messages,
+                &certs,
+                &policy,
+                &mut manager,
+            )?;
+            decrypted_messages.extend(new_messages);
+        }
+
+        let shares = decrypted_messages
+            .values()
+            .map(|message| Share::try_from(message.as_slice()))
+            .collect::<Result<Vec<_>, &str>>()
+            .map_err(|e| SharksError::Share(e.to_string()))?;
+        Ok((shares, threshold))
+    }
+
+    fn decrypt_one_shard(
+        &self,
+        private_keys: Option<Self::PrivateKeyData>,
+        encrypted_data: &[Self::EncryptedData],
+    ) -> std::result::Result<(Share, u8), Self::Error> {
+        let policy = NullPolicy::new();
+        let mut keyring = Keyring::new(private_keys.unwrap_or_default())?;
+        let mut manager = SmartcardManager::new()?;
+
+        let mut encrypted_messages = encrypted_data.iter();
+
+        let metadata = encrypted_messages.next().expect("metadata");
+        let metadata_content = decrypt_metadata(metadata, &policy, &mut keyring, &mut manager)?;
+
+        let (threshold, root_cert, certs) = decode_metadata_v1(&metadata_content)?;
+
+        keyring.set_root_cert(root_cert.clone());
+        manager.set_root_cert(root_cert.clone());
+        let mut messages: HashMap<KeyID, EncryptedMessage> = certs
+            .iter()
+            .map(Cert::keyid)
+            .zip(encrypted_messages.cloned())
+            .collect();
+
+        let decrypted_messages =
+            decrypt_with_keyring(&mut messages, &certs, &policy, &mut keyring)?;
+
+        if let Some(message) = decrypted_messages.into_values().next() {
+            let share = Share::try_from(message.as_slice())
+                .map_err(|e| SharksError::Share(e.to_string()))?;
+            return Ok((share, threshold));
+        }
+
+        let decrypted_messages =
+            decrypt_with_manager(1, &mut messages, &certs, &policy, &mut manager)?;
+
+        if let Some(message) = decrypted_messages.into_values().next() {
+            let share = Share::try_from(message.as_slice())
+                .map_err(|e| SharksError::Share(e.to_string()))?;
+            return Ok((share, threshold));
+        }
+
+        panic!("unable to decrypt shard");
+    }
+}
+
+impl KeyDiscovery<OpenPGP> for &Path {
+    fn discover_public_keys(&self) -> Result<Vec<<OpenPGP as Format>::PublicKey>> {
+        OpenPGP::discover_certs(self)
+    }
+
+    fn discover_private_keys(&self) -> Result<<OpenPGP as Format>::PrivateKeyData> {
+        todo!()
+    }
+}
+
+impl KeyDiscovery<OpenPGP> for &[Cert] {
+    fn discover_public_keys(&self) -> Result<Vec<<OpenPGP as Format>::PublicKey>> {
+        Ok(self.to_vec())
+    }
+
+    fn discover_private_keys(&self) -> Result<<OpenPGP as Format>::PrivateKeyData> {
+        Ok(self.to_vec())
+    }
+}
+
 /// Read all OpenPGP certificates in a path and return a [`Vec`] of them. Certificates are read
 /// from a file, or from files one level deep in a directory.
 ///
 /// # Errors
 /// The function may return an error if it is unable to read the directory or if Sequoia is unable
 /// to load certificates from the file.
+#[deprecated]
 pub fn discover_certs(path: impl AsRef<Path>) -> Result<Vec<Cert>> {
     let path = path.as_ref();
 
@@ -245,6 +624,7 @@ pub fn discover_certs(path: impl AsRef<Path>) -> Result<Vec<Cert>> {
 /// # Panics
 /// When given packets that are not a list of PKESK packets and SEIP packets, the function panics.
 /// The `split` utility should never give packets that are not in this format.
+#[deprecated]
 pub fn parse_messages(reader: impl Read + Send + Sync) -> Result<VecDeque<EncryptedMessage>> {
     let mut pkesks = Vec::new();
     let mut encrypted_messages = VecDeque::new();
@@ -416,6 +796,7 @@ fn decrypt_metadata(
     })
 }
 
+#[deprecated]
 fn decrypt_one(
     messages: Vec<EncryptedMessage>,
     certs: &[Cert],
@@ -465,13 +846,14 @@ fn decrypt_one(
 /// The function may panic if a share is decrypted but has a length larger than 256 bits. This is
 /// atypical usage and should not be encountered in normal usage, unless something that is not a
 /// Keyfork seed has been fed into [`split`].
+#[deprecated]
+#[allow(deprecated)]
 pub fn decrypt(
     certs: &[Cert],
     metadata: &EncryptedMessage,
     encrypted_messages: &[EncryptedMessage],
 ) -> Result<()> {
     let mut pm = Terminal::new(stdin(), stdout())?;
-    let wordlist = Wordlist::default();
 
     let mut nonce_data: Option<[u8; 12]> = None;
     let mut pubkey_data: Option<[u8; 32]> = None;
@@ -496,8 +878,11 @@ pub fn decrypt(
             let validator = MnemonicSetValidator {
                 word_lengths: [9, 24],
             };
-            let [nonce_mnemonic, pubkey_mnemonic] =
-                pm.prompt_validated_wordlist(QRCODE_COULDNT_READ, &wordlist, 3, validator.to_fn())?;
+            let [nonce_mnemonic, pubkey_mnemonic] = pm.prompt_validated_wordlist::<English, _>(
+                QRCODE_COULDNT_READ,
+                3,
+                validator.to_fn(),
+            )?;
 
             let nonce = nonce_mnemonic
                 .as_bytes()
@@ -514,8 +899,7 @@ pub fn decrypt(
     let nonce = Nonce::<U12>::from_slice(&nonce);
 
     let our_key = EphemeralSecret::random();
-    let our_pubkey_mnemonic =
-        Mnemonic::from_entropy(PublicKey::from(&our_key).as_bytes(), Default::default())?;
+    let our_pubkey_mnemonic = Mnemonic::from_bytes(PublicKey::from(&our_key).as_bytes())?;
 
     let shared_secret = our_key.diffie_hellman(&PublicKey::from(pubkey)).to_bytes();
 
@@ -560,7 +944,7 @@ pub fn decrypt(
     }
 
     // safety: size of out_bytes is constant and always % 4 == 0
-    let payload_mnemonic = unsafe { Mnemonic::from_raw_entropy(&out_bytes, Default::default()) };
+    let payload_mnemonic = unsafe { Mnemonic::from_raw_bytes(&out_bytes) };
 
     #[cfg(feature = "qrcode")]
     {
@@ -592,6 +976,7 @@ pub fn decrypt(
 /// # Errors
 /// The function may return an error if an error occurs while decrypting shards, parsing shards, or
 /// combining the shards into a secret.
+#[deprecated]
 pub fn combine(
     certs: Vec<Cert>,
     metadata: &EncryptedMessage,
@@ -679,6 +1064,7 @@ pub fn combine(
 ///
 /// The function may panic if the metadata can't properly store the certificates used to generate
 /// the encrypted shares.
+#[deprecated]
 pub fn split(threshold: u8, certs: Vec<Cert>, secret: &[u8], output: impl Write) -> Result<()> {
     let seed = VariableLengthSeed::new(secret);
     // build cert to sign encrypted shares

crates/keyfork-shard/src/openpgp/keyring.rs

@@ -111,12 +111,10 @@ impl DecryptionHelper for &mut Keyring {
                 pkesk.recipient().is_wildcard()
                     || cert.keys().any(|k| &k.keyid() == pkesk.recipient())
             }) {
-                #[allow(deprecated, clippy::map_flatten)]
                 let name = cert
                     .userids()
                     .next()
-                    .map(|userid| userid.userid().name().transpose())
-                    .flatten()
+                    .and_then(|userid| userid.userid().name2().transpose())
                     .transpose()
                     .ok()
                     .flatten();

crates/keyfork/Cargo.toml

@@ -43,3 +43,4 @@ openpgp-card-sequoia = { version = "0.2.0", default-features = false }
 openpgp-card = "0.4.1"
 clap_complete = { version = "4.4.6", optional = true }
 sequoia-openpgp = { version = "1.17.0", default-features = false, features = ["compression"] }
+keyfork-bin = { version = "0.1.0", path = "../util/keyfork-bin" }

crates/keyfork/src/cli/mnemonic.rs

@@ -109,7 +109,7 @@ impl MnemonicSeedSource {
             MnemonicSeedSource::Tarot => todo!(),
             MnemonicSeedSource::Dice => todo!(),
         };
-        let mnemonic = keyfork_mnemonic_util::Mnemonic::from_entropy(&seed, Default::default())?;
+        let mnemonic = keyfork_mnemonic_util::Mnemonic::from_bytes(&seed)?;
         Ok(mnemonic.to_string())
     }
 }

crates/keyfork/src/cli/recover.rs

@@ -2,11 +2,8 @@ use super::Keyfork;
 use clap::{Parser, Subcommand};
 use std::path::PathBuf;
 
-use keyfork_mnemonic_util::Mnemonic;
-use keyfork_shard::{
-    openpgp::{combine, discover_certs, parse_messages},
-    remote_decrypt,
-};
+use keyfork_mnemonic_util::{English, Mnemonic};
+use keyfork_shard::{remote_decrypt, Format};
 
 type Result<T, E = Box<dyn std::error::Error>> = std::result::Result<T, E>;
 
@@ -37,15 +34,10 @@ impl RecoverSubcommands {
             } => {
                 let content = std::fs::read_to_string(shard_file)?;
                 if content.contains("BEGIN PGP MESSAGE") {
-                    let certs = key_discovery
-                        .as_ref()
-                        .map(discover_certs)
-                        .transpose()?
-                        .unwrap_or(vec![]);
-                    let mut messages = parse_messages(content.as_bytes())?;
-                    let metadata = messages.pop_front().expect("any pgp encrypted message");
-                    let mut seed = vec![];
-                    combine(certs, &metadata, messages.into(), &mut seed)?;
+                    let openpgp = keyfork_shard::openpgp::OpenPGP;
+                    // TODO: remove .clone() by making handle() consume self
+                    let seed = openpgp
+                        .decrypt_all_shards_to_secret(key_discovery.as_deref(), content.as_bytes())?;
                     Ok(seed)
                 } else {
                     panic!("unknown format of shard file");
@@ -69,9 +61,8 @@ impl RecoverSubcommands {
                 let validator = MnemonicChoiceValidator {
                     word_lengths: [WordLength::Count(12), WordLength::Count(24)],
                 };
-                let mnemonic = term.prompt_validated_wordlist(
+                let mnemonic = term.prompt_validated_wordlist::<English, _>(
                     "Mnemonic: ",
-                    &Default::default(),
                     3,
                     validator.to_fn(),
                 )?;
@@ -90,7 +81,7 @@ pub struct Recover {
 impl Recover {
     pub fn handle(&self, _k: &Keyfork) -> Result<()> {
         let seed = self.command.handle()?;
-        let mnemonic = Mnemonic::from_entropy(&seed, Default::default())?;
+        let mnemonic = Mnemonic::from_bytes(&seed)?;
         tokio::runtime::Builder::new_multi_thread()
             .enable_all()
             .build()

crates/keyfork/src/cli/shard.rs

@@ -1,5 +1,6 @@
 use super::Keyfork;
 use clap::{builder::PossibleValue, Parser, Subcommand, ValueEnum};
+use keyfork_shard::Format as _;
 use std::{
     io::{stdin, stdout, Read, Write},
     path::{Path, PathBuf},
@@ -31,27 +32,23 @@ trait ShardExec {
         &self,
         threshold: u8,
         max: u8,
-        key_discovery: impl AsRef<Path>,
+        key_discovery: &Path,
         secret: &[u8],
+        output: &mut (impl Write + Send + Sync),
+    ) -> Result<(), Box<dyn std::error::Error>>;
+
+    fn combine(
+        &self,
+        key_discovery: Option<&Path>,
+        input: impl Read + Send + Sync,
         output: &mut impl Write,
     ) -> Result<(), Box<dyn std::error::Error>>;
 
-    fn combine<T>(
+    fn decrypt(
         &self,
-        key_discovery: Option<T>,
+        key_discovery: Option<&Path>,
         input: impl Read + Send + Sync,
-        output: &mut impl Write,
-    ) -> Result<(), Box<dyn std::error::Error>>
-    where
-        T: AsRef<Path>;
-
-    fn decrypt<T>(
-        &self,
-        key_discovery: Option<T>,
-        input: impl Read + Send + Sync,
-    ) -> Result<(), Box<dyn std::error::Error>>
-    where
-        T: AsRef<Path>;
+    ) -> Result<(), Box<dyn std::error::Error>>;
 }
 
 #[derive(Clone, Debug)]
@@ -62,77 +59,36 @@ impl ShardExec for OpenPGP {
         &self,
         threshold: u8,
         max: u8,
-        key_discovery: impl AsRef<Path>,
+        key_discovery: &Path,
         secret: &[u8],
-        output: &mut impl Write,
+        output: &mut (impl Write + Send + Sync),
     ) -> Result<(), Box<dyn std::error::Error>> {
-        // Get certs and input
-        let certs = keyfork_shard::openpgp::discover_certs(key_discovery.as_ref())?;
-        assert_eq!(
-            certs.len(),
-            max.into(),
-            "cert count {} != max {max}",
-            certs.len()
-        );
-        keyfork_shard::openpgp::split(threshold, certs, secret, output).map_err(Into::into)
+        let opgp = keyfork_shard::openpgp::OpenPGP;
+        opgp.shard_and_encrypt(threshold, max, secret, key_discovery, output)
     }
 
-    fn combine<T>(
+    fn combine(
         &self,
-        key_discovery: Option<T>,
+        key_discovery: Option<&Path>,
         input: impl Read + Send + Sync,
         output: &mut impl Write,
     ) -> Result<(), Box<dyn std::error::Error>>
-    where
-        T: AsRef<Path>,
     {
-        let certs = key_discovery
-            .map(|kd| keyfork_shard::openpgp::discover_certs(kd.as_ref()))
-            .transpose()?
-            .unwrap_or(vec![]);
-
-        let mut encrypted_messages = keyfork_shard::openpgp::parse_messages(input)?;
-        let encrypted_metadata = encrypted_messages
-            .pop_front()
-            .expect("any pgp encrypted message");
-
-        let mut bytes = vec![];
-
-        keyfork_shard::openpgp::combine(
-            certs,
-            &encrypted_metadata,
-            encrypted_messages.into(),
-            &mut bytes,
-        )?;
-
-        write!(output, "{}", smex::encode(&bytes))?;
+        let openpgp = keyfork_shard::openpgp::OpenPGP;
+        let bytes = openpgp.decrypt_all_shards_to_secret(key_discovery, input)?;
+        write!(output, "{}", smex::encode(bytes))?;
 
         Ok(())
     }
 
-    fn decrypt<T>(
+    fn decrypt(
         &self,
-        key_discovery: Option<T>,
+        key_discovery: Option<&Path>,
         input: impl Read + Send + Sync,
     ) -> Result<(), Box<dyn std::error::Error>>
-    where
-        T: AsRef<Path>,
     {
-        let certs = key_discovery
-            .map(|kd| keyfork_shard::openpgp::discover_certs(kd.as_ref()))
-            .transpose()?
-            .unwrap_or(vec![]);
-
-        let mut encrypted_messages = keyfork_shard::openpgp::parse_messages(input)?;
-        let encrypted_metadata = encrypted_messages
-            .pop_front()
-            .expect("any pgp encrypted message");
-
-        keyfork_shard::openpgp::decrypt(
-            &certs,
-            &encrypted_metadata,
-            encrypted_messages.make_contiguous(),
-        )?;
+        let openpgp = keyfork_shard::openpgp::OpenPGP;
+        openpgp.decrypt_one_shard_for_transport(key_discovery, input)?;
         Ok(())
     }
 }
@@ -225,7 +181,7 @@ impl ShardSubcommands {
 
                 match format {
                     Some(Format::OpenPGP(o)) => {
-                        o.decrypt(key_discovery.as_ref(), shard_content.as_bytes())
+                        o.decrypt(key_discovery.as_deref(), shard_content.as_bytes())
                     }
                     Some(Format::P256(_p)) => todo!(),
                     None => panic!("{COULD_NOT_DETERMINE_FORMAT}"),
@@ -242,7 +198,7 @@ impl ShardSubcommands {
 
                 match format {
                     Some(Format::OpenPGP(o)) => o.combine(
-                        key_discovery.as_ref(),
+                        key_discovery.as_deref(),
                         shard_content.as_bytes(),
                         &mut stdout,
                     ),

crates/keyfork/src/cli/wizard.rs

@@ -15,6 +15,8 @@ use keyfork_prompt::{
     Message, PromptHandler, Terminal,
 };
 
+use keyfork_shard::{Format, openpgp::OpenPGP};
+
 #[derive(thiserror::Error, Debug)]
 #[error("Invalid PIN length: {0}")]
 pub struct PinLength(usize);
@@ -163,11 +165,13 @@ fn generate_shard_secret(
         certs.push(cert);
     }
 
+    let opgp = OpenPGP;
+
     if let Some(output_file) = output_file {
         let output = File::create(output_file)?;
-        keyfork_shard::openpgp::split(threshold, certs, &seed, output)?;
+        opgp.shard_and_encrypt(threshold, certs.len() as u8, &seed, &certs[..], output)?;
     } else {
-        keyfork_shard::openpgp::split(threshold, certs, &seed, std::io::stdout())?;
+        opgp.shard_and_encrypt(threshold, certs.len() as u8, &seed, &certs[..], std::io::stdout())?;
     }
     Ok(())
 }

crates/keyfork/src/main.rs

@@ -6,21 +6,16 @@ use std::process::ExitCode;
 
 use clap::Parser;
 
+use keyfork_bin::{Bin, ClosureBin};
+
 mod cli;
 mod config;
 
 fn main() -> ExitCode {
-    let opts = cli::Keyfork::parse();
+    let bin = ClosureBin::new(|| {
+        let opts = cli::Keyfork::parse();
+        opts.command.handle(&opts)
+    });
 
-    if let Err(e) = opts.command.handle(&opts) {
-        eprintln!("Unable to run command: {e}");
-        let mut source = e.source();
-        while let Some(new_error) = source.take() {
-            eprintln!("Source: {new_error}");
-            source = new_error.source();
-        }
-        return ExitCode::FAILURE;
-    }
-
-    ExitCode::SUCCESS
+    bin.main()
 }

crates/util/keyfork-bin/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "keyfork-bin"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+
+[dev-dependencies]
+anyhow = "1.0.79"

crates/util/keyfork-bin/src/lib.rs

@@ -0,0 +1,140 @@
+#![allow(clippy::needless_doctest_main)]
+
+//! A convenient trait for quickly writing binaries in a consistent pattern.
+//!
+//! # Examples
+//! ```rust
+//! use anyhow::anyhow;
+//! use keyfork_bin::Bin;
+//!
+//! struct Main;
+//!
+//! impl Bin for Main {
+//!     type Args = (String, String);
+//!
+//!     fn usage_hint(&self) -> Option<String> {
+//!         Some(String::from("<param1> <param2>"))
+//!     }
+//!
+//!     fn validate_args(&self, mut args: impl Iterator<Item = String>) -> keyfork_bin::ProcessResult<Self::Args> {
+//!         let arg1 = args.next().ok_or(anyhow!("missing argument 1"))?;
+//!         let arg2 = args.next().ok_or(anyhow!("missing argument 2"))?;
+//!         Ok((arg1, arg2))
+//!     }
+//!
+//!     fn run(&self, (arg1, arg2): Self::Args) -> keyfork_bin::ProcessResult {
+//!         println!("First argument: {arg1}");
+//!         println!("Second argument: {arg2}");
+//!         Ok(())
+//!     }
+//!#
+//!#    fn main(&self) -> std::process::ExitCode {
+//!#        self.main_inner([String::from("hello"), String::from("world")].into_iter())
+//!#    }
+//! }
+//!
+//! fn main() {
+//!     // Assume the program was called with something like "hello world"...
+//!     let bin = Main;
+//!     bin.main();
+//! }
+//! ```
+
+use std::process::ExitCode;
+
+/// A result that may contain any error.
+pub type ProcessResult<T = ()> = Result<T, Box<dyn std::error::Error>>;
+
+fn report_err(e: Box<dyn std::error::Error>) {
+    eprintln!("Unable to run command: {e}");
+    let mut source = e.source();
+    while let Some(new_error) = source.take() {
+        eprintln!("- Caused by: {new_error}");
+        source = new_error.source();
+    }
+}
+
+/// A trait for implementing the flow of a binary's execution.
+pub trait Bin {
+    /// The type for command-line arguments required by the function.
+    type Args;
+
+    /// A usage hint for how the arguments should be provided to the program.
+    fn usage_hint(&self) -> Option<String> {
+        None
+    }
+
+    /// Validate the arguments provided by the user into types required by the binary.
+    #[allow(clippy::missing_errors_doc)]
+    fn validate_args(&self, args: impl Iterator<Item = String>) -> ProcessResult<Self::Args>;
+
+    /// Run the binary 
+    #[allow(clippy::missing_errors_doc)]
+    fn run(&self, args: Self::Args) -> ProcessResult;
+
+    /// The default handler for running the binary and reporting any errors.
+    fn main(&self) -> ExitCode {
+        self.main_inner(std::env::args())
+    }
+
+    #[doc(hidden)]
+    fn main_inner(&self, mut args: impl Iterator<Item = String>) -> ExitCode {
+        let command = args.next();
+        let args = match self.validate_args(args) {
+            Ok(args) => args,
+            Err(e) => {
+                if let (Some(command), Some(hint)) = (command, self.usage_hint()) {
+                    eprintln!("Usage: {command} {hint}");
+                }
+                report_err(e);
+                return ExitCode::FAILURE;
+            }
+        };
+
+        if let Err(e) = self.run(args) {
+            report_err(e);
+            return ExitCode::FAILURE;
+        }
+
+        ExitCode::SUCCESS
+    }
+}
+
+/// A Bin that doesn't take any arguments.
+pub struct ClosureBin<F: Fn() -> ProcessResult> {
+    closure: F
+}
+
+impl<F> ClosureBin<F> where F: Fn() -> ProcessResult {
+    /// Create a new Bin from a closure.
+    ///
+    /// # Examples
+    /// ```rust
+    /// use keyfork_bin::{Bin, ClosureBin};
+    ///
+    /// let bin = ClosureBin::new(|| {
+    ///     println!("Hello, world!");
+    ///     Ok(())
+    /// });
+    ///
+    /// bin.main();
+    /// ```
+    pub fn new(closure: F) -> Self {
+        Self {
+            closure
+        }
+    }
+}
+
+impl<F> Bin for ClosureBin<F> where F: Fn() -> ProcessResult {
+    type Args = ();
+
+    fn validate_args(&self, _args: impl Iterator<Item = String>) -> ProcessResult<Self::Args> {
+        Ok(())
+    }
+
+    fn run(&self, _args: Self::Args) -> ProcessResult {
+        let c = &self.closure;
+        c()
+    }
+}

crates/util/keyfork-entropy/src/lib.rs

@@ -57,10 +57,21 @@ fn ensure_offline() {
 /// # std::env::set_var("SHOOT_SELF_IN_FOOT", "1");
 /// keyfork_entropy::ensure_safe();
 /// ```
+///
+/// When running on a system that's online, or running an outdated kernel:
+///
+/// ```rust,should_panic
+/// # // NOTE: sometimes, the environment variable is set, for testing purposes. I'm not sure how
+/// # // to un-set it. Set it to a sentinel value.
+/// # std::env::set_var("SHOOT_SELF_IN_FOOT", "test-must-fail");
+/// # std::env::set_var("INSECURE_HARDWARE_ALLOWED", "test-must-fail");
+/// keyfork_entropy::ensure_safe();
+/// ```
 pub fn ensure_safe() {
-    if !std::env::vars()
-        .any(|(name, _)| name == "SHOOT_SELF_IN_FOOT" || name == "INSECURE_HARDWARE_ALLOWED")
-    {
+    if !std::env::vars().any(|(name, value)| {
+        (name == "SHOOT_SELF_IN_FOOT" || name == "INSECURE_HARDWARE_ALLOWED")
+            && value != "test-must-fail"
+    }) {
         ensure_safe_kernel_version();
         ensure_offline();
     }

crates/util/keyfork-entropy/src/main.rs

@@ -16,7 +16,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     );
 
     let entropy = keyfork_entropy::generate_entropy_of_size(bit_size / 8)?;
-    println!("{}", smex::encode(&entropy));
+    println!("{}", smex::encode(entropy));
 
     Ok(())
 }

crates/util/keyfork-frame/src/lib.rs

@@ -66,6 +66,11 @@ pub(crate) fn hash(data: &[u8]) -> Vec<u8> {
 /// # Errors
 /// An error may be returned if the given `data` is more than [`u32::MAX`] bytes. This is a
 /// constraint on a protocol level.
+///
+/// # Examples
+/// ```rust
+/// let data = keyfork_frame::try_encode(b"hello world!".as_slice()).unwrap();
+/// ```
 pub fn try_encode(data: &[u8]) -> Result<Vec<u8>, EncodeError> {
     let mut output = vec![];
     try_encode_to(data, &mut output)?;
@@ -77,6 +82,12 @@ pub fn try_encode(data: &[u8]) -> Result<Vec<u8>, EncodeError> {
 /// # Errors
 /// An error may be returned if the givenu `data` is more than [`u32::MAX`] bytes, or if the writer
 /// is unable to write data.
+///
+/// # Examples
+/// ```rust
+/// let mut output = vec![];
+/// keyfork_frame::try_encode_to(b"hello world!".as_slice(), &mut output).unwrap();
+/// ```
 pub fn try_encode_to(data: &[u8], writable: &mut impl Write) -> Result<(), EncodeError> {
     let hash = hash(data);
     let len = hash.len() + data.len();
@@ -107,18 +118,40 @@ pub(crate) fn verify_checksum(data: &[u8]) -> Result<&[u8], DecodeError> {
 /// * The given `data` does not contain enough data to parse a length,
 /// * The given `data` does not contain the given length's worth of data,
 /// * The given `data` has a checksum that does not match what we build locally.
+///
+/// # Examples
+/// ```rust
+/// let input = b"hello world!";
+/// let encoded = keyfork_frame::try_encode(input.as_slice()).unwrap();
+/// let decoded = keyfork_frame::try_decode(&encoded).unwrap();
+/// assert_eq!(input.as_slice(), decoded.as_slice());
+/// ```
 pub fn try_decode(data: &[u8]) -> Result<Vec<u8>, DecodeError> {
     try_decode_from(&mut &data[..])
 }
 
 /// Read and decode a framed message into a `Vec<u8>`.
 ///
+/// Note that unlike [`try_encode_to`], this method does not allow writing to an object
+/// implementing Write. This is because the data must be stored entirely in memory to allow
+/// verifying the data. The data is then returned using the same in-memory representation as is
+/// used in memory, and a caller may then choose to use `writable.write_all()`.
+///
 /// # Errors
 /// An error may be returned if:
 /// * The given `data` does not contain enough data to parse a length,
 /// * The given `data` does not contain the given length's worth of data,
 /// * The given `data` has a checksum that does not match what we build locally.
 /// * The source for the data returned an error.
+///
+/// # Examples
+/// ```rust
+/// let input = b"hello world!";
+/// let mut encoded = vec![];
+/// keyfork_frame::try_encode_to(input.as_slice(), &mut encoded).unwrap();
+/// let decoded = keyfork_frame::try_decode_from(&mut &encoded[..]).unwrap();
+/// assert_eq!(input.as_slice(), decoded.as_slice());
+/// ```
 pub fn try_decode_from(readable: &mut impl Read) -> Result<Vec<u8>, DecodeError> {
     let mut bytes = 0u32.to_be_bytes();
     readable.read_exact(&mut bytes)?;

crates/util/keyfork-mnemonic-util/src/bin/keyfork-mnemonic-from-seed.rs

@@ -8,7 +8,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     input.read_line(&mut line)?;
     let decoded = smex::decode(line.trim())?;
 
-    let mnemonic = unsafe { Mnemonic::from_raw_entropy(&decoded, Default::default()) };
+    let mnemonic = unsafe { Mnemonic::from_raw_bytes(&decoded) };
 
     println!("{mnemonic}");
 

crates/util/keyfork-mnemonic-util/src/lib.rs

@@ -1,6 +1,60 @@
-//! Zero-dependency Mnemonic encoding and decoding.
+//! Zero-dependency mnemonic encoding and decoding of data.
+//!
+//! Mnemonics can be used to safely encode data of 32, 48, and 64 bytes as a phrase:
+//!
+//! ```rust
+//! use keyfork_mnemonic_util::Mnemonic;
+//! let data = b"Hello, world! I am a mnemonic :)";
+//! assert_eq!(data.len(), 32);
+//! let mnemonic = Mnemonic::from_bytes(data).unwrap();
+//! println!("Our mnemonic is: {mnemonic}");
+//! ```
+//!
+//! A mnemonic can also be parsed from a string:
+//!
+//! ```rust
+//! use keyfork_mnemonic_util::Mnemonic;
+//! use std::str::FromStr;
+//!
+//! let data = b"Hello, world! I am a mnemonic :)";
+//! let words = "embody clock brand tattoo search desert saddle eternal
+//!              goddess animal banner dolphin bitter mother loyal asset
+//!              hover clock forward system normal mosquito trim credit";
+//! let mnemonic = Mnemonic::from_str(words).unwrap();
+//! assert_eq!(&data[..], mnemonic.as_bytes());
+//! ```
+//!
+//! Mnemonics can also be used to store data of other lengths, but such functionality is not
+//! verified to be safe:
+//!
+//! ```rust
+//! use keyfork_mnemonic_util::Mnemonic;
+//! let data = b"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA";
+//! let mnemonic = unsafe { Mnemonic::from_raw_bytes(data.as_slice()) };
+//! let mnemonic_text = mnemonic.to_string();
+//! ```
+//!
+//! If given an invalid length, undefined behavior may follow, or code may panic.
+//!
+//! ```rust,should_panic
+//! use keyfork_mnemonic_util::Mnemonic;
+//! use std::str::FromStr;
+//!
+//! // NOTE: Data is of invalid length, 31
+//! let data = b"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA";
+//! let mnemonic = unsafe { Mnemonic::from_raw_bytes(data.as_slice()) };
+//! let mnemonic_text = mnemonic.to_string();
+//! // NOTE: panic happens here
+//! let new_mnemonic = Mnemonic::from_str(&mnemonic_text).unwrap();
+//! ```
 
-use std::{error::Error, fmt::Display, str::FromStr, sync::Arc};
+use std::{
+    error::Error,
+    fmt::Display,
+    str::FromStr,
+    sync::OnceLock,
+    marker::PhantomData,
+};
 
 use hmac::Hmac;
 use pbkdf2::pbkdf2;
@@ -39,93 +93,65 @@ impl Display for MnemonicGenerationError {
 
 impl Error for MnemonicGenerationError {}
 
-/// A BIP-0039 compatible list of words.
-#[derive(Debug, Clone)]
-pub struct Wordlist(Vec<String>);
+/// A trait representing a BIP-0039 wordlist, of 2048 words, with each word having a unique first
+/// three letters.
+pub trait Wordlist: std::fmt::Debug {
+    /// Get a reference to a [`std::sync::OnceLock`] Self.
+    fn get_singleton<'a>() -> &'a Self;
 
-impl Default for Wordlist {
-    /// Returns the English wordlist in the Bitcoin BIP-0039 specification.
-    fn default() -> Self {
-        // TODO: English is the only supported language.
-        let wordlist_file = include_str!("data/wordlist.txt");
-        Wordlist(
-            wordlist_file
-                .lines()
-                // skip 1: comment at top of file to point to BIP-0039 source.
-                .skip(1)
-                .map(|x| x.trim().to_string())
-                .collect(),
-        )
-    }
+    /// Return a representation of the words in the wordlist as an array of [`str`].
+    fn to_str_array(&self) -> [&str; 2048];
 }
 
-impl Wordlist {
-    /// Return an Arced version of the Wordlist
-    #[allow(clippy::must_use_candidate)]
-    pub fn arc(self) -> Arc<Self> {
-        Arc::new(self)
+/// A wordlist for the English language, from the BIP-0039 dataset.
+#[derive(Debug)]
+pub struct English {
+    words: [String; 2048],
+}
+
+static ENGLISH: OnceLock<English> = OnceLock::new();
+
+impl Wordlist for English {
+    fn get_singleton<'a>() -> &'a Self {
+        ENGLISH.get_or_init(|| {
+            let wordlist_file = include_str!("data/wordlist.txt");
+            let mut words = wordlist_file
+                .lines()
+                .skip(1)
+                .map(|x| x.trim().to_string());
+            English {
+                words: std::array::from_fn(|_| words.next().expect("wordlist has 2048 words")),
+            }
+        })
     }
 
-    /// Determine whether the Wordlist contains a given word.
-    pub fn contains(&self, word: &str) -> bool {
-        self.0.iter().any(|w| w.as_str() == word)
-    }
-
-    /// Given an index, get a word from the wordlist.
-    pub fn get_word(&self, word: usize) -> Option<&String> {
-        self.0.get(word)
-    }
-
-    /*
-    fn inner(&self) -> &Vec<String> {
-        &self.0
-    }
-    */
-
-    #[cfg(test)]
-    fn into_inner(self) -> Vec<String> {
-        self.0
+    fn to_str_array(&self) -> [&str; 2048] {
+        std::array::from_fn(|i| self.words[i].as_str())
     }
 }
 
 /// A BIP-0039 mnemonic with reference to a [`Wordlist`].
-#[derive(Debug, Clone)]
-pub struct Mnemonic {
-    entropy: Vec<u8>,
-    // words: Vec<usize>,
-    wordlist: Arc<Wordlist>,
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct MnemonicBase<W: Wordlist> {
+    data: Vec<u8>,
+    marker: PhantomData<W>,
 }
 
-impl Display for Mnemonic {
+/// A default Mnemonic using the English language.
+pub type Mnemonic = MnemonicBase<English>;
+
+impl<W> Display for MnemonicBase<W>
+where
+    W: Wordlist,
+{
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        let bit_count = self.entropy.len() * 8;
-        let mut bits = vec![false; bit_count + bit_count / 32];
+        let wordlist = W::get_singleton();
+        let words = wordlist.to_str_array();
 
-        for byte_index in 0..bit_count / 8 {
-            for bit_index in 0..8 {
-                bits[byte_index * 8 + bit_index] =
-                    (self.entropy[byte_index] & (1 << (7 - bit_index))) > 0;
-            }
-        }
-
-        let mut hasher = Sha256::new();
-        hasher.update(&self.entropy);
-        let hash = hasher.finalize().to_vec();
-        for check_bit in 0..bit_count / 32 {
-            bits[bit_count + check_bit] = (hash[check_bit / 8] & (1 << (7 - (check_bit % 8)))) > 0;
-        }
-
-        let mut iter = bits
-            .chunks_exact(11)
-            .peekable()
-            .map(|chunk| {
-                let mut num = 0usize;
-                for i in 0..11 {
-                    num += usize::from(chunk[10 - i]) << i;
-                }
-                num
-            })
-            .filter_map(|word| self.wordlist.get_word(word))
+        let mut iter = self
+            .words()
+            .into_iter()
+            .filter_map(|word| words.get(word))
             .peekable();
         while let Some(word) = iter.next() {
             f.write_str(word)?;
@@ -170,17 +196,20 @@ impl Display for MnemonicFromStrError {
 
 impl Error for MnemonicFromStrError {}
 
-impl FromStr for Mnemonic {
+impl<W> FromStr for MnemonicBase<W>
+where
+    W: Wordlist,
+{
     type Err = MnemonicFromStrError;
 
     fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let wordlist = W::get_singleton();
+        let wordlist_words = wordlist.to_str_array();
         let words: Vec<_> = s.split_whitespace().collect();
         let mut usize_words = vec![];
-        let wordlist = Wordlist::default().arc();
         let mut bits = vec![false; words.len() * 11];
         for (index, word) in words.iter().enumerate() {
-            let word = wordlist
-                .0
+            let word = wordlist_words
                 .iter()
                 .position(|w| w == word)
                 .ok_or(MnemonicFromStrError::InvalidWord(index))?;
@@ -197,7 +226,7 @@ impl FromStr for Mnemonic {
         bits.truncate(bits.len() * 32 / 33);
         // bits.truncate(bits.len() - bits.len() % 32);
 
-        let entropy: Vec<u8> = bits
+        let data: Vec<u8> = bits
             .chunks_exact(8)
             .map(|chunk| {
                 let mut num = 0u8;
@@ -209,7 +238,7 @@ impl FromStr for Mnemonic {
             .collect();
 
         let mut hasher = Sha256::new();
-        hasher.update(&entropy);
+        hasher.update(&data);
         let hash = hasher.finalize().to_vec();
 
         for (i, bit) in checksum_bits.iter().enumerate() {
@@ -218,23 +247,27 @@ impl FromStr for Mnemonic {
             }
         }
 
-        Ok(Mnemonic {
-            entropy,
-            // words: usize_words,
-            wordlist,
-        })
+        Ok(MnemonicBase { data, marker: PhantomData })
     }
 }
 
-impl Mnemonic {
-    /// Generate a [`Mnemonic`] from the provided entropy and [`Wordlist`].
+impl<W> MnemonicBase<W>
+where
+    W: Wordlist,
+{
+    /// Generate a [`Mnemonic`] from the provided data and [`Wordlist`]. The data is expected to be
+    /// of 128, 192, or 256 bits, as per BIP-0039.
     ///
     /// # Errors
-    /// An error may be returned if the entropy is not within the acceptable lengths.
-    pub fn from_entropy(
-        bytes: &[u8],
-        wordlist: Arc<Wordlist>,
-    ) -> Result<Mnemonic, MnemonicGenerationError> {
+    /// An error may be returned if the data is not within the expected lengths.
+    ///
+    /// # Examples
+    /// ```rust
+    /// use keyfork_mnemonic_util::Mnemonic;
+    /// let data = b"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA";
+    /// let mnemonic = Mnemonic::from_bytes(data.as_slice()).unwrap();
+    /// ```
+    pub fn from_bytes(bytes: &[u8]) -> Result<MnemonicBase<W>, MnemonicGenerationError> {
         let bit_count = bytes.len() * 8;
 
         if bit_count % 32 != 0 {
@@ -245,88 +278,150 @@ impl Mnemonic {
             return Err(MnemonicGenerationError::InvalidByteLength(bit_count));
         }
 
-        Ok(unsafe { Self::from_raw_entropy(bytes, wordlist) })
+        Ok(unsafe { Self::from_raw_bytes(bytes) })
     }
 
+    /// Generate a [`Mnemonic`] from the provided data and [`Wordlist`]. The data is expected to be
+    /// of 128, 192, or 256 bits, as per BIP-0039.
+    ///
+    /// # Errors
+    /// An error may be returned if the data is not within the expected lengths.
+    #[deprecated = "use Mnemonic::from_bytes"]
+    pub fn from_entropy(bytes: &[u8]) -> Result<MnemonicBase<W>, MnemonicGenerationError> {
+        MnemonicBase::from_bytes(bytes)
+    }
+
+    /// Create a Mnemonic using an arbitrary length of given data. The length does not need to
+    /// conform to BIP-0039 standards, but should be a multiple of 32 bits or 4 bytes.
+    ///
     /// # Safety
     ///
     /// This function can potentially produce mnemonics that are not BIP-0039 compliant or can't
     /// properly be encoded as a mnemonic. It is assumed the caller asserts the byte count is `% 4
-    /// == 0`.
-    pub unsafe fn from_raw_entropy(bytes: &[u8], wordlist: Arc<Wordlist>) -> Mnemonic {
-        Mnemonic {
-            entropy: bytes.to_vec(),
-            wordlist,
+    /// == 0`. If the assumption is incorrect, code may panic.
+    ///
+    /// # Examples
+    /// ```rust
+    /// use keyfork_mnemonic_util::Mnemonic;
+    /// let data = b"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA";
+    /// let mnemonic = unsafe { Mnemonic::from_raw_bytes(data.as_slice()) };
+    /// let mnemonic_text = mnemonic.to_string();
+    /// ```
+    ///
+    /// If given an invalid length, undefined behavior may follow, or code may panic.
+    ///
+    /// ```rust,should_panic
+    /// use keyfork_mnemonic_util::Mnemonic;
+    /// use std::str::FromStr;
+    ///
+    /// // NOTE: Data is of invalid length, 31
+    /// let data = b"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA";
+    /// let mnemonic = unsafe { Mnemonic::from_raw_bytes(data.as_slice()) };
+    /// let mnemonic_text = mnemonic.to_string();
+    /// // NOTE: panic happens here
+    /// let new_mnemonic = Mnemonic::from_str(&mnemonic_text).unwrap();
+    /// ```
+    pub unsafe fn from_raw_bytes(bytes: &[u8]) -> MnemonicBase<W> {
+        MnemonicBase {
+            data: bytes.to_vec(),
+            marker: PhantomData,
         }
     }
 
-    /// The internal representation of the decoded data.
+    /// Create a Mnemonic using an arbitrary length of given data. The length does not need to
+    /// conform to BIP-0039 standards, but should be a multiple of 32 bits or 4 bytes.
+    ///
+    /// # Safety
+    ///
+    /// This function can potentially produce mnemonics that are not BIP-0039 compliant or can't
+    /// properly be encoded as a mnemonic. It is assumed the caller asserts the byte count is `% 4
+    /// == 0`. If the assumption is incorrect, code may panic.
+    #[deprecated = "use Mnemonic::from_raw_bytes"]
+    pub unsafe fn from_raw_entropy(bytes: &[u8]) -> MnemonicBase<W> {
+        MnemonicBase {
+            data: bytes.to_vec(),
+            marker: PhantomData,
+        }
+    }
+
+    /// A view to internal representation of the decoded data.
     pub fn as_bytes(&self) -> &[u8] {
-        &self.entropy
+        &self.data
     }
 
-    /// The internal representation of the decoded data, as a [`Vec<u8>`].
+    /// A clone of the internal representation of the decoded data.
     pub fn to_bytes(&self) -> Vec<u8> {
-        self.entropy.to_vec()
+        self.data.to_vec()
     }
 
-    /// Drop self, returning the decoded data.
+    /// Conver the Mnemonic into the internal representation of the decoded data.
     pub fn into_bytes(self) -> Vec<u8> {
-        self.entropy
+        self.data
     }
 
-    /// Clone the existing entropy.
+    /// Clone the existing data.
     #[deprecated = "Use as_bytes(), to_bytes(), or into_bytes() instead"]
     pub fn entropy(&self) -> Vec<u8> {
-        self.entropy.clone()
+        self.data.clone()
     }
 
     /// Create a BIP-0032 seed from the provided data and an optional passphrase.
     ///
     /// # Errors
-    /// The method may return an error if the pbkdf2 function returns an invalid length, but this
-    /// case should not be reached.
+    /// The method should not return an error.
+    #[deprecated = "Use generate_seed() instead"]
     pub fn seed<'a>(
         &self,
         passphrase: impl Into<Option<&'a str>>,
     ) -> Result<Vec<u8>, MnemonicGenerationError> {
+        Ok(self.generate_seed(passphrase))
+    }
+
+    /// Create a BIP-0032 seed from the provided data and an optional passphrase.
+    ///
+    /// # Panics
+    /// The function may panic if the HmacSha512 function returns an error. The only error the
+    /// HmacSha512 function should return is an invalid length, which should not be possible.
+    ///
+    pub fn generate_seed<'a>(&self, passphrase: impl Into<Option<&'a str>>) -> Vec<u8> {
         let passphrase = passphrase.into();
 
         let mut seed = [0u8; 64];
         let mnemonic = self.to_string();
         let salt = ["mnemonic", passphrase.unwrap_or("")].join("");
         pbkdf2::<Hmac<Sha512>>(mnemonic.as_bytes(), salt.as_bytes(), 2048, &mut seed)
-            .map_err(|_| MnemonicGenerationError::InvalidPbkdf2Length)?;
-        Ok(seed.to_vec())
+            .expect("HmacSha512 InvalidLength should be infallible");
+        seed.to_vec()
     }
 
-    /// Encode the mnemonic into a list of wordlist indexes.
-    pub fn words(self) -> (Vec<usize>, Arc<Wordlist>) {
-        let bit_count = self.entropy.len() * 8;
+    /// Encode the mnemonic into a list of integers 11 bits in length, matching the length of a
+    /// BIP-0039 wordlist.
+    pub fn words(&self) -> Vec<usize> {
+        let bit_count = self.data.len() * 8;
         let mut bits = vec![false; bit_count + bit_count / 32];
 
         for byte_index in 0..bit_count / 8 {
             for bit_index in 0..8 {
                 bits[byte_index * 8 + bit_index] =
-                    (self.entropy[byte_index] & (1 << (7 - bit_index))) > 0;
+                    (self.data[byte_index] & (1 << (7 - bit_index))) > 0;
             }
         }
 
         let mut hasher = Sha256::new();
-        hasher.update(&self.entropy);
+        hasher.update(&self.data);
         let hash = hasher.finalize().to_vec();
         for check_bit in 0..bit_count / 32 {
             bits[bit_count + check_bit] = (hash[check_bit / 8] & (1 << (7 - (check_bit % 8)))) > 0;
         }
 
-        let words = bits.chunks_exact(11).peekable().map(|chunk| {
+        // TODO: find a way to not have to collect to vec
+        bits.chunks_exact(11).peekable().map(|chunk| {
             let mut num = 0usize;
             for i in 0..11 {
                 num += usize::from(chunk[10 - i]) << i;
             }
             num
-        });
-        (words.collect(), self.wordlist.clone())
+        }).collect()
     }
 }
 
@@ -337,13 +432,8 @@ mod tests {
     use super::*;
 
     #[test]
-    fn wordlist_word_count_correct() {
-        let wordlist = Wordlist::default().into_inner();
-        assert_eq!(
-            wordlist.len(),
-            2usize.pow(11),
-            "Wordlist did not include correct word count"
-        );
+    fn can_load_wordlist() {
+        let _wordlist = English::get_singleton();
     }
 
     #[test]
@@ -351,8 +441,7 @@ mod tests {
         let mut random_handle = File::open("/dev/random").unwrap();
         let entropy = &mut [0u8; 256 / 8];
         random_handle.read_exact(&mut entropy[..]).unwrap();
-        let wordlist = Wordlist::default().arc();
-        let mnemonic = super::Mnemonic::from_entropy(&entropy[..256 / 8], wordlist).unwrap();
+        let mnemonic = super::Mnemonic::from_bytes(&entropy[..256 / 8]).unwrap();
         let new_entropy = mnemonic.as_bytes();
         assert_eq!(new_entropy, entropy);
     }
@@ -361,7 +450,6 @@ mod tests {
     fn conforms_to_trezor_tests() {
         let content = include_str!("data/vectors.json");
         let jsonobj: serde_json::Value = serde_json::from_str(content).unwrap();
-        let wordlist = Wordlist::default().arc();
 
         for test in jsonobj["english"].as_array().unwrap() {
             let [ref hex_, ref seed, ..] = test.as_array().unwrap()[..] else {
@@ -369,7 +457,7 @@ mod tests {
             };
             let hex = hex::decode(hex_.as_str().unwrap()).unwrap();
 
-            let mnemonic = Mnemonic::from_entropy(&hex, wordlist.clone()).unwrap();
+            let mnemonic = Mnemonic::from_bytes(&hex).unwrap();
 
             assert_eq!(mnemonic.to_string(), seed.as_str().unwrap());
         }
@@ -380,17 +468,16 @@ mod tests {
         let mut random_handle = File::open("/dev/random").unwrap();
         let entropy = &mut [0u8; 256 / 8];
         random_handle.read_exact(&mut entropy[..]).unwrap();
-        let wordlist = Wordlist::default().arc();
-        let my_mnemonic = super::Mnemonic::from_entropy(&entropy[..256 / 8], wordlist).unwrap();
+        let my_mnemonic = Mnemonic::from_bytes(&entropy[..256 / 8]).unwrap();
         let their_mnemonic = bip39::Mnemonic::from_entropy(&entropy[..256 / 8]).unwrap();
         assert_eq!(my_mnemonic.to_string(), their_mnemonic.to_string());
-        assert_eq!(my_mnemonic.seed(None).unwrap(), their_mnemonic.to_seed(""));
+        assert_eq!(my_mnemonic.generate_seed(None), their_mnemonic.to_seed(""));
         assert_eq!(
-            my_mnemonic.seed("testing").unwrap(),
+            my_mnemonic.generate_seed("testing"),
             their_mnemonic.to_seed("testing")
         );
         assert_ne!(
-            my_mnemonic.seed("test1").unwrap(),
+            my_mnemonic.generate_seed("test1"),
             their_mnemonic.to_seed("test2")
         );
     }
@@ -400,14 +487,13 @@ mod tests {
         let tests = 100_000;
         let mut count = 0.;
         let entropy = &mut [0u8; 256 / 8];
-        let wordlist = Wordlist::default().arc();
         let mut random = std::fs::File::open("/dev/urandom").unwrap();
         let mut hs = HashSet::<usize>::with_capacity(24);
 
         for _ in 0..tests {
             random.read_exact(&mut entropy[..]).unwrap();
-            let mnemonic = Mnemonic::from_entropy(&entropy[..256 / 8], wordlist.clone()).unwrap();
-            let (words, _) = mnemonic.words();
+            let mnemonic = Mnemonic::from_bytes(&entropy[..256 / 8]).unwrap();
+            let words = mnemonic.words();
             hs.clear();
             hs.extend(words);
             if hs.len() != 24 {
@@ -435,11 +521,10 @@ mod tests {
     #[test]
     fn can_do_up_to_1024_bits() {
         let entropy = &mut [0u8; 128];
-        let wordlist = Wordlist::default().arc();
         let mut random = std::fs::File::open("/dev/urandom").unwrap();
         random.read_exact(&mut entropy[..]).unwrap();
-        let mnemonic = unsafe { Mnemonic::from_raw_entropy(&entropy[..], wordlist.clone()) };
-        let (words, _) = mnemonic.words();
+        let mnemonic = unsafe { Mnemonic::from_raw_bytes(&entropy[..]) };
+        let words = mnemonic.words();
         assert!(words.len() == 96);
     }
 }

crates/util/keyfork-prompt/examples/test-basic-prompt.rs

@@ -7,6 +7,8 @@ use keyfork_prompt::{
     Terminal, PromptHandler,
 };
 
+use keyfork_mnemonic_util::English;
+
 fn main() -> Result<(), Box<dyn std::error::Error>> {
     let mut mgr = Terminal::new(stdin(), stdout())?;
     let transport_validator = mnemonic::MnemonicSetValidator {
@@ -16,18 +18,16 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
         word_lengths: [24, 48],
     };
 
-    let mnemonics = mgr.prompt_validated_wordlist(
+    let mnemonics = mgr.prompt_validated_wordlist::<English, _>(
         "Enter a 9-word and 24-word mnemonic: ",
-        &Default::default(),
         3,
         transport_validator.to_fn(),
     )?;
     assert_eq!(mnemonics[0].as_bytes().len(), 12);
     assert_eq!(mnemonics[1].as_bytes().len(), 32);
 
-    let mnemonics = mgr.prompt_validated_wordlist(
+    let mnemonics = mgr.prompt_validated_wordlist::<English, _>(
         "Enter a 24 and 48-word mnemonic: ",
-        &Default::default(),
         3,
         combine_validator.to_fn(),
     )?;

crates/util/keyfork-prompt/src/lib.rs

@@ -51,31 +51,31 @@ pub trait PromptHandler {
     /// could not be read.
     fn prompt_input(&mut self, prompt: &str) -> Result<String>;
 
-    /// Prompt the user for input based on a wordlist.
+    /// Prompt the user for input based on a wordlist. A language must be specified as the generic
+    /// parameter `X` (any type implementing [`Wordlist`]) when parsing a wordlist.
     ///
     /// # Errors
     /// The method may return an error if the message was not able to be displayed or if the input
     /// could not be read.
     #[cfg(feature = "mnemonic")]
-    fn prompt_wordlist(&mut self, prompt: &str, wordlist: &Wordlist) -> Result<String>;
+    fn prompt_wordlist<X>(&mut self, prompt: &str) -> Result<String> where X: Wordlist;
 
     /// Prompt the user for input based on a wordlist, while validating the wordlist using a
-    /// provided parser function, returning the type from the parser.
+    /// provided parser function, returning the type from the parser. A language must be specified
+    /// as the generic parameter `X` (any type implementing [`Wordlist`]) when parsing a wordlist.
     ///
     /// # Errors
     /// The method may return an error if the message was not able to be displayed, if the input
     /// could not be read, or if the parser returned an error.
     #[cfg(feature = "mnemonic")]
-    fn prompt_validated_wordlist<V, F, E>(
+    fn prompt_validated_wordlist<X, V>(
         &mut self,
         prompt: &str,
-        wordlist: &Wordlist,
         retries: u8,
-        validator_fn: F,
+        validator_fn: impl Fn(String) -> Result<V, Box<dyn std::error::Error>>,
     ) -> Result<V, Error>
     where
-        F: Fn(String) -> Result<V, E>,
-        E: std::error::Error;
+        X: Wordlist;
 
     /// Prompt the user for a passphrase, which is hidden while typing.
     ///
@@ -90,15 +90,12 @@ pub trait PromptHandler {
     /// # Errors
     /// The method may return an error if the message was not able to be displayed, if the input
     /// could not be read, or if the parser returned an error.
-    fn prompt_validated_passphrase<V, F, E>(
+    fn prompt_validated_passphrase<V>(
         &mut self,
         prompt: &str,
         retries: u8,
-        validator_fn: F,
-    ) -> Result<V, Error>
-    where
-        F: Fn(String) -> Result<V, E>,
-        E: std::error::Error;
+        validator_fn: impl Fn(String) -> Result<V, Box<dyn std::error::Error>>,
+    ) -> Result<V, Error>;
 
     /// Prompt the user with a [`Message`].
     ///

crates/util/keyfork-prompt/src/terminal.rs

@@ -1,6 +1,7 @@
 use std::{
+    borrow::Borrow,
     io::{stderr, stdin, BufRead, BufReader, Read, Stderr, Stdin, Write},
-    os::fd::AsRawFd, borrow::Borrow,
+    os::fd::AsRawFd,
 };
 
 use keyfork_crossterm::{
@@ -12,7 +13,7 @@ use keyfork_crossterm::{
     ExecutableCommand, QueueableCommand,
 };
 
-use crate::{PromptHandler, Message, Wordlist, Error};
+use crate::{Error, Message, PromptHandler, Wordlist};
 
 #[allow(missing_docs)]
 pub type Result<T, E = Error> = std::result::Result<T, E>;
@@ -155,11 +156,13 @@ where
     fn lock(&mut self) -> TerminalGuard<'_, R, W> {
         TerminalGuard::new(&mut self.read, &mut self.write, &mut self.terminal)
     }
-
 }
 
-impl<R, W> PromptHandler for Terminal<R, W> where R: Read + Sized, W: Write + AsRawFd + Sized {
-
+impl<R, W> PromptHandler for Terminal<R, W>
+where
+    R: Read + Sized,
+    W: Write + AsRawFd + Sized,
+{
     fn prompt_input(&mut self, prompt: &str) -> Result<String> {
         let mut terminal = self.lock().alternate_screen()?;
         terminal
@@ -182,20 +185,18 @@ impl<R, W> PromptHandler for Terminal<R, W> where R: Read + Sized, W: Write + As
     }
 
     #[cfg(feature = "mnemonic")]
-    fn prompt_validated_wordlist<V, F, E>(
+    fn prompt_validated_wordlist<X, V>(
         &mut self,
         prompt: &str,
-        wordlist: &Wordlist,
         retries: u8,
-        validator_fn: F,
+        validator_fn: impl Fn(String) -> Result<V, Box<dyn std::error::Error>>,
     ) -> Result<V, Error>
     where
-        F: Fn(String) -> Result<V, E>,
-        E: std::error::Error,
+        X: Wordlist,
     {
         let mut last_error = None;
         for _ in 0..retries {
-            let s = self.prompt_wordlist(prompt, wordlist)?;
+            let s = self.prompt_wordlist::<X>(prompt)?;
             match validator_fn(s) {
                 Ok(v) => return Ok(v),
                 Err(e) => {
@@ -214,7 +215,13 @@ impl<R, W> PromptHandler for Terminal<R, W> where R: Read + Sized, W: Write + As
 
     #[cfg(feature = "mnemonic")]
     #[allow(clippy::too_many_lines)]
-    fn prompt_wordlist(&mut self, prompt: &str, wordlist: &Wordlist) -> Result<String> {
+    fn prompt_wordlist<X>(&mut self, prompt: &str) -> Result<String>
+    where
+        X: Wordlist,
+    {
+        let wordlist = X::get_singleton();
+        let words = wordlist.to_str_array();
+
         let mut terminal = self
             .lock()
             .alternate_screen()?
@@ -316,7 +323,7 @@ impl<R, W> PromptHandler for Terminal<R, W> where R: Read + Sized, W: Write + As
             let mut iter = printable_input.split_whitespace().peekable();
 
             while let Some(word) = iter.next() {
-                if wordlist.contains(word) {
+                if words.contains(&word) {
                     terminal.queue(PrintStyledContent(word.green()))?;
                 } else {
                     terminal.queue(PrintStyledContent(word.red()))?;
@@ -337,16 +344,12 @@ impl<R, W> PromptHandler for Terminal<R, W> where R: Read + Sized, W: Write + As
         Ok(input)
     }
 
-    fn prompt_validated_passphrase<V, F, E>(
+    fn prompt_validated_passphrase<V>(
         &mut self,
         prompt: &str,
         retries: u8,
-        validator_fn: F,
-    ) -> Result<V, Error>
-    where
-        F: Fn(String) -> Result<V, E>,
-        E: std::error::Error,
-    {
+        validator_fn: impl Fn(String) -> Result<V, Box<dyn std::error::Error>>,
+    ) -> Result<V, Error> {
         let mut last_error = None;
         for _ in 0..retries {
             let s = self.prompt_passphrase(prompt)?;

crates/util/keyfork-prompt/src/validators.rs

@@ -12,7 +12,7 @@ pub trait Validator {
     type Error;
 
     /// Create a validator function from the given parameters.
-    fn to_fn(&self) -> Box<dyn Fn(String) -> Result<Self::Output, Self::Error>>;
+    fn to_fn(&self) -> Box<dyn Fn(String) -> Result<Self::Output, Box<dyn std::error::Error>>>;
 }
 
 /// A PIN could not be validated from the given input.
@@ -48,7 +48,7 @@ impl Validator for PinValidator {
     type Output = String;
     type Error = PinError;
 
-    fn to_fn(&self) -> Box<dyn Fn(String) -> Result<String, PinError>> {
+    fn to_fn(&self) -> Box<dyn Fn(String) -> Result<String, Box<dyn std::error::Error>>> {
         let min_len = self.min_length.unwrap_or(usize::MIN);
         let max_len = self.max_length.unwrap_or(usize::MAX);
         let range = self.range.clone().unwrap_or('0'..='9');
@@ -56,14 +56,14 @@ impl Validator for PinValidator {
             s.truncate(s.trim_end().len());
             let len = s.len();
             if len < min_len {
-                return Err(PinError::TooShort(len, min_len));
+                return Err(Box::new(PinError::TooShort(len, min_len)));
             }
             if len > max_len {
-                return Err(PinError::TooLong(len, max_len));
+                return Err(Box::new(PinError::TooLong(len, max_len)));
             }
             for (index, ch) in s.chars().enumerate() {
                 if !range.contains(&ch) {
-                    return Err(PinError::InvalidCharacters(ch, index));
+                    return Err(Box::new(PinError::InvalidCharacters(ch, index)));
                 }
             }
             Ok(s)
@@ -123,13 +123,13 @@ pub mod mnemonic {
         type Output = Mnemonic;
         type Error = MnemonicValidationError;
 
-        fn to_fn(&self) -> Box<dyn Fn(String) -> Result<Mnemonic, Self::Error>> {
+        fn to_fn(&self) -> Box<dyn Fn(String) -> Result<Mnemonic, Box<dyn std::error::Error>>> {
             let word_length = self.word_length.clone();
             Box::new(move |s: String| match word_length.as_ref() {
                 Some(wl) => {
                     let count = s.split_whitespace().count();
                     if !wl.matches(count) {
-                        return Err(Self::Error::InvalidLength(count, wl.clone()));
+                        return Err(Box::new(Self::Error::InvalidLength(count, wl.clone())));
                     }
                     let m = Mnemonic::from_str(&s)?;
                     Ok(m)
@@ -165,7 +165,7 @@ pub mod mnemonic {
         type Output = Mnemonic;
         type Error = MnemonicChoiceValidationError;
 
-        fn to_fn(&self) -> Box<dyn Fn(String) -> Result<Self::Output, Self::Error>> {
+        fn to_fn(&self) -> Box<dyn Fn(String) -> Result<Self::Output, Box<dyn std::error::Error>>> {
             let word_lengths = self.word_lengths.clone();
             Box::new(move |s: String| {
                 let count = s.split_whitespace().count();
@@ -175,10 +175,10 @@ pub mod mnemonic {
                         return Ok(m);
                     }
                 }
-                Err(MnemonicChoiceValidationError::InvalidLength(
+                Err(Box::new(MnemonicChoiceValidationError::InvalidLength(
                     count,
                     word_lengths.to_vec(),
-                ))
+                )))
             })
         }
     }
@@ -207,7 +207,7 @@ pub mod mnemonic {
         type Output = [Mnemonic; N];
         type Error = MnemonicSetValidationError;
 
-        fn to_fn(&self) -> Box<dyn Fn(String) -> Result<Self::Output, Self::Error>> {
+        fn to_fn(&self) -> Box<dyn Fn(String) -> Result<Self::Output, Box<dyn std::error::Error>>> {
             let word_lengths = self.word_lengths;
             Box::new(move |s: String| {
                 let mut counter: usize = 0;
@@ -219,15 +219,17 @@ pub mod mnemonic {
                         .take(word_length)
                         .collect::<Vec<_>>();
                     if words.len() != word_length {
-                        return Err(MnemonicSetValidationError::InvalidSetLength(
+                        return Err(Box::new(MnemonicSetValidationError::InvalidSetLength(
                             word_set,
                             words.len(),
                             word_length,
-                        ));
+                        )));
                     }
                     let mnemonic = match Mnemonic::from_str(&words.join(" ")) {
                         Ok(m) => m,
-                        Err(e) => return Err(Self::Error::MnemonicFromStrError(word_set, e)),
+                        Err(e) => {
+                            return Err(Box::new(Self::Error::MnemonicFromStrError(word_set, e)))
+                        }
                     };
                     output.push(mnemonic);
                     counter += word_length;

crates/util/smex/src/lib.rs

@@ -28,7 +28,15 @@ impl std::fmt::Display for DecodeError {
 impl std::error::Error for DecodeError {}
 
 /// Encode a given input as a hex string.
-pub fn encode(input: &[u8]) -> String {
+///
+/// # Examples
+/// ```rust
+/// let data = b"hello world!";
+/// let result = smex::encode(&data);
+/// assert_eq!(result, "68656c6c6f20776f726c6421");
+/// ```
+pub fn encode(input: impl AsRef<[u8]>) -> String {
+    let input = input.as_ref();
     let mut s = String::new();
     for byte in input {
         write!(s, "{byte:02x}").unwrap();
@@ -50,7 +58,26 @@ fn val(c: u8) -> Result<u8, DecodeError> {
 /// # Errors
 /// The function may error if a non-hex character is encountered or if the character count is not
 /// evenly divisible by two.
-pub fn decode(input: &str) -> Result<Vec<u8>, DecodeError> {
+///
+/// # Examples
+/// ```rust
+/// let data = b"hello world!";
+/// let encoded = smex::encode(&data);
+/// let decoded = smex::decode(&encoded).unwrap();
+/// assert_eq!(data.as_slice(), decoded.as_slice());
+/// ```
+///
+/// The function may return an error if the given input is not valid hex.
+///
+/// ```rust,should_panic
+/// let data = b"hello world!";
+/// let mut encoded = smex::encode(&data);
+/// encoded.push('G');
+/// let decoded = smex::decode(&encoded).unwrap();
+/// assert_eq!(data.as_slice(), decoded.as_slice());
+/// ```
+pub fn decode(input: impl AsRef<str>) -> Result<Vec<u8>, DecodeError> {
+    let input = input.as_ref();
     let len = input.len();
     if len % 2 != 0 {
         return Err(DecodeError::InvalidCharacterCount(len));