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keyfork-shard: add instructions for sending QR code to operators

This commit is contained in:
Ryan Heywood 2024-02-05 20:19:05 -05:00
parent d6b52a8f0a
commit 1879a250c8
Signed by: ryan
GPG Key ID: 8E401478A3FBEF72
2 changed files with 44 additions and 13 deletions
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32
crates/keyfork-shard/src/lib.rs
View File

@ -46,6 +46,8 @@ pub(crate) const HUNK_OFFSET: usize = 2;
const QRCODE_PROMPT: &str = "Press enter, then present QR code to camera.";
const QRCODE_TIMEOUT: u64 = 60; // One minute
const QRCODE_COULDNT_READ: &str = "A QR code could not be scanned. Please enter their words: ";
const QRCODE_ERROR: &str = "Unable to scan a QR code. Falling back to text entry.";
/// Establish ECDH transport for remote operators, receive transport-encrypted shares, decrypt the
/// shares, and combine them.
@ -67,8 +69,10 @@ pub fn remote_decrypt(w: &mut impl Write) -> Result<(), Box<dyn std::error::Erro
let mut shares = vec![];
let mut threshold = 0;
let mut iter = 0;
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()) };
@ -82,12 +86,26 @@ pub fn remote_decrypt(w: &mut impl Write) -> Result<(), Box<dyn std::error::Erro
let mut qrcode_data = nonce_mnemonic.to_bytes();
qrcode_data.extend(key_mnemonic.as_bytes());
if let Ok(qrcode) = qrencode(&smex::encode(&qrcode_data), ErrorCorrection::Highest) {
pm.prompt_message(PromptMessage::Text(format!(
concat!(
"A QR code will be displayed after this prompt. ",
"Send the QR code to only shardholder {iter}. ",
"Nobody else should scan this QR code."
),
iter = iter
)))?;
pm.prompt_message(PromptMessage::Data(qrcode))?;
}
}
pm.prompt_message(PromptMessage::Text(format!(
"Our words: {nonce_mnemonic} {key_mnemonic}"
concat!(
"Upon request, these words should be sent to shardholder {iter}: ",
"{nonce_mnemonic} {key_mnemonic}"
),
iter = iter,
nonce_mnemonic = nonce_mnemonic,
key_mnemonic = key_mnemonic,
)))?;
let mut pubkey_data: Option<[u8; 32]> = None;
@ -103,9 +121,7 @@ pub fn remote_decrypt(w: &mut impl Write) -> Result<(), Box<dyn std::error::Erro
let _ = pubkey_data.insert(decoded_data[..32].try_into().map_err(|_| InvalidData)?);
let _ = payload_data.insert(decoded_data[32..].to_vec());
} else {
pm.prompt_message(PromptMessage::Text(
"Unable to detect QR code, falling back to text".to_string(),
))?;
pm.prompt_message(PromptMessage::Text(QRCODE_ERROR.to_string()))?;
};
}
@ -116,8 +132,12 @@ 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("Their words: ", &wordlist, 3, validator.to_fn())?;
let [pubkey_mnemonic, payload_mnemonic] = pm.prompt_validated_wordlist(
QRCODE_COULDNT_READ,
&wordlist,
3,
validator.to_fn(),
)?;
let pubkey = pubkey_mnemonic
.as_bytes()
.try_into()

25
crates/keyfork-shard/src/openpgp.rs
View File

@ -56,7 +56,10 @@ use smartcard::SmartcardManager;
const SHARD_METADATA_VERSION: u8 = 1;
const SHARD_METADATA_OFFSET: usize = 2;
use super::{InvalidData, SharksError, HUNK_VERSION, QRCODE_PROMPT, QRCODE_TIMEOUT};
use super::{
InvalidData, SharksError, HUNK_VERSION, QRCODE_COULDNT_READ, QRCODE_ERROR, QRCODE_PROMPT,
QRCODE_TIMEOUT,
};
// 256 bit share is 49 bytes + some amount of hunk bytes, gives us reasonable padding
const ENC_LEN: u8 = 4 * 16;
@ -472,14 +475,14 @@ pub fn decrypt(
#[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(QRCODE_TIMEOUT), 0) {
if let Ok(Some(hex)) =
keyfork_qrcode::scan_camera(std::time::Duration::from_secs(QRCODE_TIMEOUT), 0)
{
let decoded_data = smex::decode(&hex)?;
let _ = nonce_data.insert(decoded_data[..12].try_into().map_err(|_| InvalidData)?);
let _ = pubkey_data.insert(decoded_data[12..].try_into().map_err(|_| InvalidData)?);
} else {
pm.prompt_message(PromptMessage::Text(
"Unable to detect QR code, falling back to text".to_string(),
))?;
pm.prompt_message(PromptMessage::Text(QRCODE_ERROR.to_string()))?;
};
}
@ -490,7 +493,7 @@ pub fn decrypt(
word_lengths: [9, 24],
};
let [nonce_mnemonic, pubkey_mnemonic] =
pm.prompt_validated_wordlist("Their words: ", &wordlist, 3, validator.to_fn())?;
pm.prompt_validated_wordlist(QRCODE_COULDNT_READ, &wordlist, 3, validator.to_fn())?;
let nonce = nonce_mnemonic
.as_bytes()
@ -561,12 +564,20 @@ pub fn decrypt(
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!(
"Our words: {our_pubkey_mnemonic} {payload_mnemonic}"
"Upon request, these words should be sent: {our_pubkey_mnemonic} {payload_mnemonic}"
)))?;
Ok(())