From 95416f875107706c911606b7a14cd76b52f6a787 Mon Sep 17 00:00:00 2001
From: Hernando Castano <hernando@hcastano.com>
Date: Mon, 12 Aug 2024 18:13:55 -0400
Subject: [PATCH] Handle BIP-32 errors instead of panicking

---
 Cargo.lock                                                    | 3 +++
 crates/threshold-signature-server/Cargo.toml                  | 3 ++-
 crates/threshold-signature-server/src/helpers/signing.rs      | 2 +-
 .../threshold-signature-server/src/signing_client/errors.rs   | 2 ++
 .../src/signing_client/protocol_execution/mod.rs              | 4 ++--
 5 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index cffe24e2e..2a125d758 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -831,6 +831,8 @@ dependencies = [
  "bs58 0.5.1",
  "hmac 0.12.1",
  "k256",
+ "once_cell",
+ "pbkdf2 0.12.2",
  "rand_core 0.6.4",
  "ripemd",
  "sha2 0.10.8",
@@ -2753,6 +2755,7 @@ dependencies = [
  "backoff",
  "base64 0.22.1",
  "bincode 1.3.3",
+ "bip32",
  "bip39",
  "blake2 0.10.6",
  "blake3",
diff --git a/crates/threshold-signature-server/Cargo.toml b/crates/threshold-signature-server/Cargo.toml
index 73772b4a8..2673b8d8e 100644
--- a/crates/threshold-signature-server/Cargo.toml
+++ b/crates/threshold-signature-server/Cargo.toml
@@ -57,8 +57,9 @@ uuid                    ={ version="1.10.0", features=["v4"] }
 
 # Misc
 tokio-tungstenite="0.23.1"
-bip39            ={ version="2.0.0", features=["zeroize"] }
 bincode          ="1.3.3"
+bip32            ={ version="0.5.2" }
+bip39            ={ version="2.0.0", features=["zeroize"] }
 bytes            ={ version="1.7", default-features=false, features=["serde"] }
 base64           ="0.22.1"
 clap             ={ version="4.5.15", features=["derive"] }
diff --git a/crates/threshold-signature-server/src/helpers/signing.rs b/crates/threshold-signature-server/src/helpers/signing.rs
index fc8799687..ddab8a9d0 100644
--- a/crates/threshold-signature-server/src/helpers/signing.rs
+++ b/crates/threshold-signature-server/src/helpers/signing.rs
@@ -45,7 +45,7 @@ pub async fn do_signing(
     app_state: &AppState,
     signing_session_info: SigningSessionInfo,
     request_limit: u32,
-    derivation_path: Option<String>, // TODO (Nando): Not a fan of this...
+    derivation_path: Option<String>,
 ) -> Result<RecoverableSignature, ProtocolErr> {
     tracing::debug!("Preparing to perform signing");
 
diff --git a/crates/threshold-signature-server/src/signing_client/errors.rs b/crates/threshold-signature-server/src/signing_client/errors.rs
index 66155004d..abe5c9065 100644
--- a/crates/threshold-signature-server/src/signing_client/errors.rs
+++ b/crates/threshold-signature-server/src/signing_client/errors.rs
@@ -108,6 +108,8 @@ pub enum ProtocolErr {
     SubstrateClient(#[from] entropy_client::substrate::SubstrateError),
     #[error("Listener: {0}")]
     Listener(#[from] entropy_protocol::errors::ListenerErr),
+    #[error("Failed to derive BIP-32 account: {0}")]
+    Bip32DerivationError(#[from] bip32::Error),
 }
 
 impl IntoResponse for ProtocolErr {
diff --git a/crates/threshold-signature-server/src/signing_client/protocol_execution/mod.rs b/crates/threshold-signature-server/src/signing_client/protocol_execution/mod.rs
index 3d348ec3c..4b161a6db 100644
--- a/crates/threshold-signature-server/src/signing_client/protocol_execution/mod.rs
+++ b/crates/threshold-signature-server/src/signing_client/protocol_execution/mod.rs
@@ -86,8 +86,8 @@ impl<'a> ThresholdSigningService<'a> {
             .ok_or_else(|| ProtocolErr::Deserialization("Failed to load KeyShare".into()))?;
 
         let key_share = if let Some(path) = derivation_path {
-            let path = path.parse().expect("TODO");
-            key_share.derive_bip32(&path).expect("TODO")
+            let path = path.parse()?;
+            key_share.derive_bip32(&path)?
         } else {
             key_share
         };