From 590a4644e2eaef5414cdfa6c60508ebf5638c0af Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bogdan-=C8=98tefan=20Neac=C5=9Fu?= <bogdan@nymtech.net>
Date: Wed, 8 Feb 2023 11:54:12 +0200
Subject: [PATCH] Skip errors on blind sign within threshold (#2976)

---
 clients/credential/src/commands.rs      |  6 ++++++
 clients/credential/src/error.rs         |  3 +++
 common/credentials/src/coconut/utils.rs | 14 ++++++++++----
 common/credentials/src/error.rs         |  3 +++
 4 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/clients/credential/src/commands.rs b/clients/credential/src/commands.rs
index a007dbf766..31ab1e225c 100644
--- a/clients/credential/src/commands.rs
+++ b/clients/credential/src/commands.rs
@@ -82,6 +82,11 @@ pub(crate) async fn get_credential(state: &State, shared_storage: PersistentStor
     let config = Config::try_from_nym_network_details(&network_details)?;
     let client = validator_client::Client::new_query(config)?;
     let epoch_id = client.nyxd.get_current_epoch().await?.epoch_id;
+    let threshold = client
+        .nyxd
+        .get_current_epoch_threshold()
+        .await?
+        .ok_or(CredentialClientError::NoThreshold)?;
     let coconut_api_clients = CoconutApiClient::all_coconut_api_clients(&client, epoch_id).await?;
 
     let params = Parameters::new(TOTAL_ATTRIBUTES).unwrap();
@@ -98,6 +103,7 @@ pub(crate) async fn get_credential(state: &State, shared_storage: PersistentStor
         &params,
         &bandwidth_credential_attributes,
         &coconut_api_clients,
+        threshold,
     )
     .await?;
     println!("Signature: {:?}", signature.to_bs58());
diff --git a/clients/credential/src/error.rs b/clients/credential/src/error.rs
index f793957e2f..360db2cf23 100644
--- a/clients/credential/src/error.rs
+++ b/clients/credential/src/error.rs
@@ -34,4 +34,7 @@ pub enum CredentialClientError {
 
     #[error("Could not use shared storage")]
     SharedStorageError(#[from] StorageError),
+
+    #[error("Threshold not set yet")]
+    NoThreshold,
 }
diff --git a/common/credentials/src/coconut/utils.rs b/common/credentials/src/coconut/utils.rs
index 12edebc3df..aca55abe0b 100644
--- a/common/credentials/src/coconut/utils.rs
+++ b/common/credentials/src/coconut/utils.rs
@@ -92,6 +92,7 @@ pub async fn obtain_aggregate_signature(
     params: &Parameters,
     attributes: &BandwidthVoucher,
     coconut_api_clients: &[CoconutApiClient],
+    threshold: u64,
 ) -> Result<Signature, Error> {
     if coconut_api_clients.is_empty() {
         return Err(Error::NoValidatorsAvailable);
@@ -110,15 +111,20 @@ pub async fn obtain_aggregate_signature(
         .collect();
 
     for coconut_api_client in coconut_api_clients.iter() {
-        let signature = obtain_partial_credential(
+        if let Ok(signature) = obtain_partial_credential(
             params,
             attributes,
             &coconut_api_client.api_client,
             &coconut_api_client.verification_key,
         )
-        .await?;
-        let share = SignatureShare::new(signature, coconut_api_client.node_id);
-        shares.push(share)
+        .await
+        {
+            let share = SignatureShare::new(signature, coconut_api_client.node_id);
+            shares.push(share)
+        }
+    }
+    if shares.len() < threshold as usize {
+        return Err(Error::NotEnoughShares);
     }
 
     let mut attributes = Vec::with_capacity(private_attributes.len() + public_attributes.len());
diff --git a/common/credentials/src/error.rs b/common/credentials/src/error.rs
index f1daaa6142..7f909e79b5 100644
--- a/common/credentials/src/error.rs
+++ b/common/credentials/src/error.rs
@@ -29,4 +29,7 @@ pub enum Error {
 
     #[error("Could not parse the key - {0}")]
     ParsePublicKey(#[from] KeyRecoveryError),
+
+    #[error("Could not gather enough signature shares")]
+    NotEnoughShares,
 }