339 lines
10 KiB
Rust
339 lines
10 KiB
Rust
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use std::{
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collections::{HashMap, VecDeque},
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io::{Read, Write},
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path::Path,
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str::FromStr,
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};
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use keyfork_derive_openpgp::derive_util::{
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request::{DerivationAlgorithm, DerivationRequest},
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DerivationPath,
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};
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use openpgp::{
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armor::{Kind, Writer},
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cert::{Cert, CertParser, ValidCert},
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packet::{Packet, Tag, UserID, PKESK, SEIP},
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parse::{stream::DecryptorBuilder, Parse},
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policy::{NullPolicy, Policy, StandardPolicy},
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serialize::{
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stream::{ArbitraryWriter, Encryptor, LiteralWriter, Message, Recipient, Signer},
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Marshal,
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},
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types::KeyFlags,
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KeyID, PacketPile
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};
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pub use sequoia_openpgp as openpgp;
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use sharks::{Share, Sharks};
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mod keyring;
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use keyring::Keyring;
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// TODO: better error handling
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#[derive(Debug, Clone)]
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pub struct WrappedError(String);
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impl std::fmt::Display for WrappedError {
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fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
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f.write_str(&self.0)
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}
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}
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impl std::error::Error for WrappedError {}
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pub type Result<T, E = Box<dyn std::error::Error>> = std::result::Result<T, E>;
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#[derive(Debug, Clone)]
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pub struct EncryptedMessage {
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pkesks: Vec<PKESK>,
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message: SEIP,
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}
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impl EncryptedMessage {
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pub fn with_swap(pkesks: &mut Vec<PKESK>, seip: SEIP) -> Self {
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Self {
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pkesks: std::mem::take(pkesks),
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message: seip,
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}
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}
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pub fn decrypt_with(&self, policy: &'_ dyn Policy, keyring: &mut Keyring) -> Result<Vec<u8>> {
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let mut packets = vec![];
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for pkesk in &self.pkesks {
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let mut packet = vec![];
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pkesk.serialize(&mut packet)?;
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let message = Message::new(&mut packets);
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let mut message = ArbitraryWriter::new(message, Tag::PKESK)?;
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message.write_all(&packet)?;
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message.finalize()?;
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}
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let mut packet = vec![];
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self.message.serialize(&mut packet)?;
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let message = Message::new(&mut packets);
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let mut message = ArbitraryWriter::new(message, Tag::SEIP)?;
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message.write_all(&packet)?;
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message.finalize()?;
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let mut decryptor =
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DecryptorBuilder::from_bytes(&packets)?.with_policy(policy, None, keyring)?;
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let mut content = vec![];
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decryptor.read_to_end(&mut content)?;
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Ok(content)
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}
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}
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pub fn discover_certs(path: impl AsRef<Path>) -> Result<Vec<Cert>> {
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let path = path.as_ref();
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if path.is_file() {
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let mut vec = vec![];
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for cert in CertParser::from_file(path)? {
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vec.push(cert?);
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}
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Ok(vec)
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} else {
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let mut vec = vec![];
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for entry in path
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.read_dir()?
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.filter_map(Result::ok)
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.filter(|p| p.path().is_file())
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{
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vec.push(Cert::from_file(entry.path())?);
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}
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Ok(vec)
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}
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}
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pub fn parse_messages(reader: impl Read + Send + Sync) -> Result<VecDeque<EncryptedMessage> >{
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let mut pkesks = Vec::new();
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let mut encrypted_messages = VecDeque::new();
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for packet in PacketPile::from_reader(reader)?.into_children() {
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match packet {
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Packet::PKESK(p) => pkesks.push(p),
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Packet::SEIP(s) => {
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encrypted_messages.push_back(EncryptedMessage::with_swap(&mut pkesks, s));
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}
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s => {
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panic!("Invalid variant found: {}", s.tag());
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}
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}
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}
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Ok(encrypted_messages)
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}
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fn get_encryption_keys<'a>(
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cert: &'a ValidCert,
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) -> openpgp::cert::prelude::ValidKeyAmalgamationIter<
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'a,
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openpgp::packet::key::PublicParts,
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openpgp::packet::key::UnspecifiedRole,
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> {
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cert.keys()
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.alive()
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.revoked(false)
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.supported()
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.for_storage_encryption()
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}
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fn get_decryption_keys<'a>(
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cert: &'a ValidCert,
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) -> openpgp::cert::prelude::ValidKeyAmalgamationIter<
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'a,
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openpgp::packet::key::SecretParts,
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openpgp::packet::key::UnspecifiedRole,
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> {
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cert.keys()
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/*
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.alive()
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.revoked(false)
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.supported()
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*/
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.for_storage_encryption()
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.secret()
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}
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pub fn combine(
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threshold: u8,
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certs: Vec<Cert>,
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metadata: EncryptedMessage,
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messages: Vec<EncryptedMessage>,
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mut output: impl Write,
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) -> Result<()> {
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// Be as liberal as possible when decrypting.
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// We don't want to invalidate someone's keys just because the old sig expired.
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let policy = NullPolicy::new();
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let mut keyring = Keyring::new(certs);
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let content = metadata.decrypt_with(&policy, &mut keyring)?;
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let mut cert_parser = CertParser::from_bytes(&content)?;
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let root_cert = match cert_parser.next() {
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Some(Ok(c)) => c,
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Some(Err(e)) => panic!("Could not find root (first) certificate: {e}"),
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None => panic!("No certs found in cert parser"),
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};
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let certs = cert_parser.collect::<openpgp::Result<Vec<_>>>()?;
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keyring.set_root_cert(root_cert);
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let mut messages: HashMap<KeyID, EncryptedMessage> =
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HashMap::from_iter(certs.iter().map(|c| c.keyid()).zip(messages));
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let mut decrypted_messages: HashMap<KeyID, Vec<u8>> = HashMap::new();
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// NOTE: This is ONLY stable because we control the generation of PKESK packets and
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// encode the policy to ourselves.
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for valid_cert in certs.iter().map(|cert| cert.with_policy(&policy, None)) {
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let valid_cert = valid_cert?;
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// get keys from keyring for cert
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let Some(secret_cert) = keyring.get_cert_for_primary_keyid(&valid_cert.keyid()) else {
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continue;
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};
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let secret_cert = secret_cert.with_policy(&policy, None)?;
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let keys = get_decryption_keys(&secret_cert).collect::<Vec<_>>();
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if !keys.is_empty() {
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if let Some(message) = messages.get_mut(&valid_cert.keyid()) {
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for (pkesk, key) in message.pkesks.iter_mut().zip(keys) {
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pkesk.set_recipient(key.keyid());
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}
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// we have a pkesk, decrypt via keyring
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let result = message.decrypt_with(&policy, &mut keyring);
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match result {
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Ok(message) => {
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decrypted_messages.insert(valid_cert.keyid(), message);
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}
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Err(e) => {
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eprintln!(
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"Could not decrypt with fingerprint {}: {}",
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valid_cert.keyid(),
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e
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);
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// do nothing, key will be retained
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}
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}
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}
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}
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}
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// clean decrypted messages from encrypted messages
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messages.retain(|k, _v| !decrypted_messages.contains_key(k));
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let left_from_threshold = threshold as usize - decrypted_messages.len();
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if left_from_threshold > 0 {
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eprintln!("remaining keys: {left_from_threshold}, prompting yubikeys");
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}
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for _ in 0..left_from_threshold {
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todo!("prompt for Yubikeys")
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}
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let shares = decrypted_messages
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.values()
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.map(|message| Share::try_from(message.as_slice()))
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.collect::<Result<Vec<_>, &str>>()
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.map_err(|e| WrappedError(e.to_string()))?;
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let secret = Sharks(threshold).recover(&shares)?;
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output.write_all(smex::encode(&secret).as_bytes())?;
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Ok(())
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}
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pub fn split(threshold: u8, certs: Vec<Cert>, secret: &[u8], output: impl Write) -> Result<()> {
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// build cert to sign encrypted shares
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let userid = UserID::from("keyfork-sss");
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let kdr = DerivationRequest::new(
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DerivationAlgorithm::Ed25519,
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&DerivationPath::from_str("m/7366512'/0'")?,
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)
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.derive_with_master_seed(secret.to_vec())?;
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let derived_cert = keyfork_derive_openpgp::derive(
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kdr,
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&[KeyFlags::empty().set_certification().set_signing()],
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userid,
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)?;
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let signing_key = derived_cert
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.primary_key()
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.parts_into_secret()?
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.key()
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.clone()
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.into_keypair()?;
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let sharks = Sharks(threshold);
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let dealer = sharks.dealer(secret);
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let shares = dealer.map(|s| Vec::from(&s)).collect::<Vec<_>>();
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let policy = StandardPolicy::new();
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let mut writer = Writer::new(output, Kind::Message)?;
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let mut total_recipients = vec![];
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let mut messages = vec![];
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for (share, cert) in shares.iter().zip(certs) {
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total_recipients.push(cert.clone());
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let valid_cert = cert.with_policy(&policy, None)?;
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let encryption_keys = get_encryption_keys(&valid_cert).collect::<Vec<_>>();
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let mut message_output = vec![];
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let message = Message::new(&mut message_output);
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let message = Encryptor::for_recipients(
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message,
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encryption_keys
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.iter()
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.map(|k| Recipient::new(KeyID::wildcard(), k.key())),
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)
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.build()?;
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let message = Signer::new(message, signing_key.clone()).build()?;
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let mut message = LiteralWriter::new(message).build()?;
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message.write_all(share)?;
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message.finalize()?;
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messages.push(message_output);
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}
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let mut pp = vec![];
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// store derived cert to verify provided shares
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derived_cert.serialize(&mut pp)?;
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for recipient in &total_recipients {
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recipient.serialize(&mut pp)?;
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}
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// verify packet pile
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for (packet_cert, cert) in openpgp::cert::CertParser::from_bytes(&pp)?
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.skip(1)
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.zip(total_recipients.iter())
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{
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if packet_cert? != *cert {
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panic!(
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"packet pile could not recreate cert: {}",
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cert.fingerprint()
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);
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}
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}
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let valid_certs = total_recipients
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.iter()
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.map(|c| c.with_policy(&policy, None))
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.collect::<openpgp::Result<Vec<_>>>()?;
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let total_recipients = valid_certs.iter().flat_map(|vc| {
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get_encryption_keys(vc).map(|key| Recipient::new(KeyID::wildcard(), key.key()))
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});
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// metadata
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let mut message_output = vec![];
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let message = Message::new(&mut message_output);
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let message = Encryptor::for_recipients(message, total_recipients).build()?;
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let mut message = LiteralWriter::new(message).build()?;
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message.write_all(&pp)?;
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message.finalize()?;
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writer.write_all(&message_output)?;
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for message in messages {
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writer.write_all(&message)?;
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}
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writer.finalize()?;
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Ok(())
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}
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