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fix: backup keys are on the secp256k1 curve #193

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Merged
paolodamico merged 4 commits into from
Mar 13, 2026
Merged

fix: backup keys are on the secp256k1 curve #193

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176e2be
fix: backup keys are k256
paolodamico Mar 13, 2026
6a9355b
extra doc
paolodamico Mar 13, 2026
ed2bf6e
fix tests
paolodamico Mar 13, 2026
407ff6b
fix
paolodamico Mar 13, 2026
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14 changes: 14 additions & 0 deletions Cargo.lock
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5 changes: 3 additions & 2 deletions Cargo.toml
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Original file line number Diff line number Diff line change
@@ -1,4 +1,3 @@

[workspace]
members = [".", "test-utils"]

Expand All @@ -15,7 +14,8 @@ rand = "0.8.0"
serde_json = "1.0.149"
sha2 = "0.10.8"
uuid = { version = "1.16.0", features = ["v4", "serde"] }
p256 = { version = "0.13.2", features = ["ecdsa"] }
p256 = { version = "0.13.2", default-features = false, features = ["ecdsa", "std"] }
k256 = { version = "0.13.4", default-features = false, features = ["ecdsa", "std"] }

# dev workspace dependencies
mockito = "1.7.1"
Expand Down Expand Up @@ -55,6 +55,7 @@ http = "1.3.1"
josekit = { version = "0.10.1", features = ["vendored"] }
openidconnect = { workspace = true }
p256 = { workspace = true }
k256 = { workspace = true }
rand = { workspace = true }
redis = { version = "0.32.5", features = ["connection-manager", "tokio-comp", "tokio-rustls-comp"] }
reqwest = { version = "0.12.22", features = ["json", "rustls-tls"] }
Expand Down
20 changes: 12 additions & 8 deletions src/routes/reset.rs
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Expand Up @@ -10,9 +10,9 @@ use axum::http::StatusCode;
use axum::{Extension, Json};
use base64::engine::general_purpose::STANDARD;
use base64::Engine;
use p256::ecdsa::signature::Verifier;
use p256::ecdsa::{Signature, VerifyingKey};
use p256::EncodedPoint;
use k256::ecdsa::signature::Verifier;
use k256::ecdsa::{Signature, VerifyingKey};
use k256::EncodedPoint;
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use schemars::JsonSchema;
use serde::{Deserialize, Serialize};
use tracing::Instrument;
Expand Down Expand Up @@ -106,6 +106,9 @@ pub async fn handler(
}

/// Extracts the public key from a `backup_account_id` and verifies a signature on a given message.
///
/// # Important
/// The `backup_account_id` is a public key on the `secp256k1` curve.
fn verify_backup_account_signature(
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backup_account_id: &str,
signature_base64: &str,
Expand Down Expand Up @@ -178,17 +181,18 @@ fn verify_backup_account_signature(
#[cfg(test)]
mod tests {
use super::*;
use p256::ecdsa::signature::Signer;
use p256::ecdsa::SigningKey;
use p256::elliptic_curve::rand_core::OsRng;
use p256::SecretKey;
use k256::ecdsa::signature::Signer;
use k256::ecdsa::SigningKey;
use k256::elliptic_curve::rand_core::OsRng;
use k256::SecretKey;

#[test]
fn test_verify_backup_account_signature_success() {
// Generate a test keypair
let secret_key = SecretKey::random(&mut OsRng);
let signing_key = SigningKey::from(&secret_key);
let verifying_key = VerifyingKey::from(&signing_key);
// Explicit use of `secp256k1` in the tests
let verifying_key = k256::ecdsa::VerifyingKey::from(&signing_key);

// Create backup_account_id from compressed public key
let compressed_bytes = verifying_key.to_encoded_point(true).as_bytes().to_vec();
Expand Down
45 changes: 28 additions & 17 deletions tests/reset_backup_integration.rs
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Expand Up @@ -20,14 +20,25 @@ use serde_json::json;
use std::sync::Arc;

/// Helper function to derive backup_account_id from a secret key
fn derive_backup_account_id_from_keypair(secret_key: &SecretKey) -> String {
let signing_key = SigningKey::from(secret_key);
let verifying_key = p256::ecdsa::VerifyingKey::from(&signing_key);
fn derive_backup_account_id_from_keypair(secret_key: &k256::SecretKey) -> String {
let signing_key = k256::ecdsa::SigningKey::from(secret_key);
let verifying_key = k256::ecdsa::VerifyingKey::from(&signing_key);
let compressed_point = verifying_key.to_encoded_point(true);
let compressed_bytes = compressed_point.as_bytes();
format!("backup_account_{}", hex::encode(compressed_bytes))
}

/// Signs a challenge using a backup key keypair. This differs from sync factors as it uses
/// the `secp256k1` curve.
fn sign_challenge_with_backup_key(secret_key: &k256::SecretKey, challenge: &str) -> String {
use k256::ecdsa::signature::Signer;
let signing_key = k256::ecdsa::SigningKey::from(secret_key.clone());
let challenge = STANDARD.decode(challenge).unwrap();
let signature: k256::ecdsa::Signature = signing_key.sign(&challenge);
let signature_der = signature.to_der();
STANDARD.encode(signature_der)
}

/// Helper function to get a reset challenge
async fn get_reset_challenge(backup_account_id: &str) -> serde_json::Value {
let challenge_response = send_post_request(
Expand Down Expand Up @@ -87,7 +98,7 @@ async fn verify_backup_deleted(backup_id: &str) {

/// Helper function to create a backup with a specific backup_account_id derived from a keypair
async fn create_test_backup_with_backup_account_id(
backup_account_secret_key: &SecretKey,
backup_account_secret_key: &k256::SecretKey,
backup_data: &[u8],
) -> (String, SecretKey, SecretKey) {
// Derive backup_account_id from the provided secret key
Expand Down Expand Up @@ -183,7 +194,7 @@ async fn test_reset_backup_happy_path() {
let factor_lookup = FactorLookup::new(environment, dynamodb_client.clone());

// Generate a keypair for the backup_account_id
let backup_account_secret_key = SecretKey::random(&mut OsRng);
let backup_account_secret_key = k256::SecretKey::random(&mut OsRng);

// Create a backup with this backup_account_id
let (backup_account_id, main_secret_key, sync_secret_key) =
Expand Down Expand Up @@ -218,7 +229,7 @@ async fn test_reset_backup_happy_path() {
let challenge_response = get_reset_challenge(&backup_account_id).await;

// Sign the challenge with the backup_account_id secret key
let signature = sign_keypair_challenge(
let signature = sign_challenge_with_backup_key(
&backup_account_secret_key,
challenge_response["challenge"].as_str().unwrap(),
);
Expand Down Expand Up @@ -257,7 +268,7 @@ async fn test_reset_backup_happy_path() {
#[tokio::test]
async fn test_reset_backup_with_incorrect_signature() {
// Generate a keypair for the backup_account_id
let backup_account_secret_key = SecretKey::random(&mut OsRng);
let backup_account_secret_key = k256::SecretKey::random(&mut OsRng);
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// Create a backup with this backup_account_id
let (backup_account_id, _, _) =
Expand Down Expand Up @@ -306,7 +317,7 @@ async fn test_reset_backup_with_incorrect_signature() {
#[tokio::test]
async fn test_reset_backup_with_mismatched_public_key() {
// Generate a keypair for the backup_account_id
let backup_account_secret_key = SecretKey::random(&mut OsRng);
let backup_account_secret_key = k256::SecretKey::random(&mut OsRng);

// Create a backup with this backup_account_id
let (backup_account_id, _, _) =
Expand Down Expand Up @@ -356,7 +367,7 @@ async fn test_reset_backup_with_mismatched_public_key() {
#[tokio::test]
async fn test_reset_backup_challenge_token_reuse() {
// Generate a keypair for the backup_account_id
let backup_account_secret_key = SecretKey::random(&mut OsRng);
let backup_account_secret_key = k256::SecretKey::random(&mut OsRng);

// Create first backup
let (backup_account_id_1, _, _) =
Expand All @@ -367,7 +378,7 @@ async fn test_reset_backup_challenge_token_reuse() {
let challenge_response = get_reset_challenge(&backup_account_id_1).await;

// Sign the challenge
let signature = sign_keypair_challenge(
let signature = sign_challenge_with_backup_key(
&backup_account_secret_key,
challenge_response["challenge"].as_str().unwrap(),
);
Expand All @@ -385,13 +396,13 @@ async fn test_reset_backup_challenge_token_reuse() {
assert_eq!(reset_response.status(), StatusCode::NO_CONTENT);

// Create a second backup with a different backup_account_id
let backup_account_secret_key_2 = SecretKey::random(&mut OsRng);
let backup_account_secret_key_2 = k256::SecretKey::random(&mut OsRng);
let (backup_account_id_2, _, _) =
create_test_backup_with_backup_account_id(&backup_account_secret_key_2, b"TEST BACKUP 2")
.await;

// Try to reuse the same challenge token on the second backup (should fail)
let signature_2 = sign_keypair_challenge(
let signature_2 = sign_challenge_with_backup_key(
&backup_account_secret_key_2,
challenge_response["challenge"].as_str().unwrap(),
);
Expand Down Expand Up @@ -428,14 +439,14 @@ async fn test_reset_backup_challenge_token_reuse() {
#[tokio::test]
async fn test_reset_nonexistent_backup() {
// Generate a keypair
let backup_account_secret_key = SecretKey::random(&mut OsRng);
let backup_account_secret_key = k256::SecretKey::random(&mut OsRng);
let backup_account_id = derive_backup_account_id_from_keypair(&backup_account_secret_key);

// Get a reset challenge (this should work even if backup doesn't exist)
let challenge_response = get_reset_challenge(&backup_account_id).await;

// Sign the challenge
let signature = sign_keypair_challenge(
let signature = sign_challenge_with_backup_key(
&backup_account_secret_key,
challenge_response["challenge"].as_str().unwrap(),
);
Expand All @@ -458,9 +469,9 @@ async fn test_reset_nonexistent_backup() {
#[tokio::test]
async fn test_reset_backup_with_wrong_backup_account_id_in_token() {
// Generate two keypairs for two different backup_account_ids
let backup_account_secret_key_1 = SecretKey::random(&mut OsRng);
let backup_account_secret_key_1 = k256::SecretKey::random(&mut OsRng);

let backup_account_secret_key_2 = SecretKey::random(&mut OsRng);
let backup_account_secret_key_2 = k256::SecretKey::random(&mut OsRng);
let backup_account_id_2 = derive_backup_account_id_from_keypair(&backup_account_secret_key_2);

// Create a backup with the first backup_account_id
Expand All @@ -472,7 +483,7 @@ async fn test_reset_backup_with_wrong_backup_account_id_in_token() {
let challenge_response = get_reset_challenge(&backup_account_id_2).await;

// Sign the challenge with the first keypair
let signature = sign_keypair_challenge(
let signature = sign_challenge_with_backup_key(
&backup_account_secret_key_1,
challenge_response["challenge"].as_str().unwrap(),
);
Expand Down