refactor(server): migrated auth to ml-dsa

server/crates/arbiter-client/src/auth.rs

@@ -1,5 +1,5 @@
 use arbiter_proto::{
-    ClientMetadata, format_challenge,
+    CLIENT_CONTEXT, ClientMetadata, format_challenge,
     proto::{
         client::{
             ClientRequest,
@@ -14,7 +14,7 @@ use arbiter_proto::{
         shared::ClientInfo as ProtoClientInfo,
     },
 };
-use ed25519_dalek::Signer as _;
+use ml_dsa::{MlDsa87, SigningKey, signature::Keypair as _};
 
 use crate::{
     storage::StorageError,
@@ -54,14 +54,14 @@ fn map_auth_result(code: i32) -> AuthError {
 async fn send_auth_challenge_request(
     transport: &mut ClientTransport,
     metadata: ClientMetadata,
-    key: &ed25519_dalek::SigningKey,
+    key: &SigningKey<MlDsa87>,
 ) -> std::result::Result<(), AuthError> {
     transport
         .send(ClientRequest {
             request_id: next_request_id(),
             payload: Some(ClientRequestPayload::Auth(proto_auth::Request {
                 payload: Some(AuthRequestPayload::ChallengeRequest(AuthChallengeRequest {
-                    pubkey: key.verifying_key().to_bytes().to_vec(),
+                    pubkey: key.verifying_key().encode().to_vec(),
                     client_info: Some(ProtoClientInfo {
                         name: metadata.name,
                         description: metadata.description,
@@ -95,11 +95,16 @@ async fn receive_auth_challenge(
 
 async fn send_auth_challenge_solution(
     transport: &mut ClientTransport,
-    key: &ed25519_dalek::SigningKey,
+    key: &SigningKey<MlDsa87>,
     challenge: AuthChallenge,
 ) -> std::result::Result<(), AuthError> {
     let challenge_payload = format_challenge(challenge.nonce, &challenge.pubkey);
-    let signature = key.sign(&challenge_payload).to_bytes().to_vec();
+    let signature = key
+        .signing_key()
+        .sign_deterministic(&challenge_payload, CLIENT_CONTEXT)
+        .map_err(|_| AuthError::UnexpectedAuthResponse)?
+        .encode()
+        .to_vec();
 
     transport
         .send(ClientRequest {
@@ -140,7 +145,7 @@ async fn receive_auth_confirmation(
 pub(crate) async fn authenticate(
     transport: &mut ClientTransport,
     metadata: ClientMetadata,
-    key: &ed25519_dalek::SigningKey,
+    key: &SigningKey<MlDsa87>,
 ) -> std::result::Result<(), AuthError> {
     send_auth_challenge_request(transport, metadata, key).await?;
     let challenge = receive_auth_challenge(transport).await?;

server/crates/arbiter-client/src/client.rs

@@ -1,6 +1,7 @@
 use arbiter_proto::{
     ClientMetadata, proto::arbiter_service_client::ArbiterServiceClient, url::ArbiterUrl,
 };
+use ml_dsa::{MlDsa87, SigningKey};
 use std::sync::Arc;
 use tokio::sync::{Mutex, mpsc};
 use tokio_stream::wrappers::ReceiverStream;
@@ -60,7 +61,7 @@ impl ArbiterClient {
     pub async fn connect_with_key(
         url: ArbiterUrl,
         metadata: ClientMetadata,
-        key: ed25519_dalek::SigningKey,
+        key: SigningKey<MlDsa87>,
     ) -> Result<Self, Error> {
         let anchor = webpki::anchor_from_trusted_cert(&url.ca_cert)?.to_owned();
         let tls = ClientTlsConfig::new().trust_anchor(anchor);

server/crates/arbiter-client/src/storage.rs

@@ -1,4 +1,5 @@
 use arbiter_proto::home_path;
+use ml_dsa::{KeyGen, MlDsa87, Seed, SigningKey};
 use std::path::{Path, PathBuf};
 
 #[derive(Debug, thiserror::Error)]
@@ -11,7 +12,7 @@ pub enum StorageError {
 }
 
 pub trait SigningKeyStorage {
-    fn load_or_create(&self) -> std::result::Result<ed25519_dalek::SigningKey, StorageError>;
+    fn load_or_create(&self) -> std::result::Result<SigningKey<MlDsa87>, StorageError>;
 }
 
 #[derive(Debug, Clone)]
@@ -20,7 +21,7 @@ pub struct FileSigningKeyStorage {
 }
 
 impl FileSigningKeyStorage {
-    pub const DEFAULT_FILE_NAME: &str = "sdk_client_ed25519.key";
+    pub const DEFAULT_FILE_NAME: &str = "sdk_client_ml_dsa.key";
 
     pub fn new(path: impl Into<PathBuf>) -> Self {
         Self { path: path.into() }
@@ -30,21 +31,20 @@ impl FileSigningKeyStorage {
         Ok(Self::new(home_path()?.join(Self::DEFAULT_FILE_NAME)))
     }
 
-    fn read_key(path: &Path) -> std::result::Result<ed25519_dalek::SigningKey, StorageError> {
+    fn read_key(path: &Path) -> std::result::Result<SigningKey<MlDsa87>, StorageError> {
         let bytes = std::fs::read(path)?;
-        let raw: [u8; 32] =
-            bytes
-                .try_into()
-                .map_err(|v: Vec<u8>| StorageError::InvalidKeyLength {
-                    expected: 32,
-                    actual: v.len(),
-                })?;
-        Ok(ed25519_dalek::SigningKey::from_bytes(&raw))
+        let raw: [u8; 32] = bytes
+            .try_into()
+            .map_err(|v: Vec<u8>| StorageError::InvalidKeyLength {
+                expected: 32,
+                actual: v.len(),
+            })?;
+        Ok(MlDsa87::from_seed(&Seed::from(raw)))
     }
 }
 
 impl SigningKeyStorage for FileSigningKeyStorage {
-    fn load_or_create(&self) -> std::result::Result<ed25519_dalek::SigningKey, StorageError> {
+    fn load_or_create(&self) -> std::result::Result<SigningKey<MlDsa87>, StorageError> {
         if let Some(parent) = self.path.parent() {
             std::fs::create_dir_all(parent)?;
         }
@@ -53,8 +53,8 @@ impl SigningKeyStorage for FileSigningKeyStorage {
             return Self::read_key(&self.path);
         }
 
-        let key = ed25519_dalek::SigningKey::generate(&mut rand::rng());
-        let raw_key = key.to_bytes();
+        let key = MlDsa87::key_gen(&mut rand::rng());
+        let raw_key = key.to_seed();
 
         // Use create_new to prevent accidental overwrite if another process creates the key first.
         match std::fs::OpenOptions::new()
@@ -103,7 +103,7 @@ mod tests {
             .load_or_create()
             .expect("second load_or_create should read same key");
 
-        assert_eq!(key_a.to_bytes(), key_b.to_bytes());
+        assert_eq!(key_a.to_seed(), key_b.to_seed());
         assert!(path.exists());
 
         std::fs::remove_file(path).expect("temp key file should be removable");