From b86f158471d74a32c63eb3538297705d4bf8e21e Mon Sep 17 00:00:00 2001
From: Emma Turner <emma.turner@trili.tech>
Date: Wed, 20 Dec 2023 11:20:17 +0000
Subject: [PATCH] crypto: Signature of all zero bytes should be Unknown

Currently defaults to Ed25519, which does not match octez reference
---
 CHANGELOG.md            |  1 +
 crypto/src/hash.rs      | 26 ++++----------------------
 crypto/src/signature.rs | 11 +++++++++++
 3 files changed, 16 insertions(+), 22 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6334e7b8a3..471edd3cc0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -36,6 +36,7 @@ parameterized by the lifetime of the input byte slice.
 - Hash input before signing with `SecretKeyEd25519`, to match octez impl.
 - Fix `BlsSignature` base58 check encoding/decoding.
 - Fix `SecretKeyEd25519` base58 check encoding/decoding.
+- Fix all zeros signature encoding: should be `Unknown` rather than defaulting to `Ed25519`.
 
 ### Security
 
diff --git a/crypto/src/hash.rs b/crypto/src/hash.rs
index 7adf2c9ab6..95d52f291c 100644
--- a/crypto/src/hash.rs
+++ b/crypto/src/hash.rs
@@ -466,12 +466,8 @@ impl HashType {
             Err(FromBytesError::InvalidSize)
         } else {
             let mut hash = Vec::with_capacity(self.base58check_prefix().len() + data.len());
-            if matches!(self, Self::UnknownSignature) && data == [0; Self::Ed25519Signature.size()]
-            {
-                hash.extend(Self::Ed25519Signature.base58check_prefix());
-            } else {
-                hash.extend(self.base58check_prefix());
-            }
+
+            hash.extend(self.base58check_prefix());
             hash.extend(data);
 
             Ok(hash.to_base58check())
@@ -481,22 +477,8 @@ impl HashType {
     /// Convert string representation of the hash to bytes form.
     pub fn b58check_to_hash(&self, data: &str) -> Result<Hash, FromBase58CheckError> {
         let mut hash = data.from_base58check()?;
-        if let HashType::UnknownSignature = self {
-            // zero signature is represented as Ed25519 signature
-            if hash.len()
-                == HashType::Ed25519Signature.size()
-                    + HashType::Ed25519Signature.base58check_prefix().len()
-            {
-                let (prefix, hash) =
-                    hash.split_at(HashType::Ed25519Signature.base58check_prefix().len());
-                if prefix == HashType::Ed25519Signature.base58check_prefix()
-                    && hash == [0; HashType::Ed25519Signature.size()]
-                {
-                    return Ok(hash.to_vec());
-                }
-            }
-        } else if !hash.starts_with(self.base58check_prefix()) {
-            println!("expected: {:?}, found: {hash:?}", self.base58check_prefix());
+
+        if !hash.starts_with(self.base58check_prefix()) {
             return Err(FromBase58CheckError::IncorrectBase58Prefix);
         }
 
diff --git a/crypto/src/signature.rs b/crypto/src/signature.rs
index 915b8bcfee..bcaa985680 100644
--- a/crypto/src/signature.rs
+++ b/crypto/src/signature.rs
@@ -124,3 +124,14 @@ impl ::std::fmt::Display for Signature {
         write!(f, "{}", self.to_base58_check())
     }
 }
+
+#[cfg(test)]
+mod test {
+    #[test]
+    fn test() {
+        assert_eq!(
+            &super::Signature::try_from([0; 64].to_vec()).unwrap().to_base58_check(),
+            "sigMzJ4GVAvXEd2RjsKGfG2H9QvqTSKCZsuB2KiHbZRGFz72XgF6KaKADznh674fQgBatxw3xdHqTtMHUZAGRprxy64wg1aq"
+        );
+    }
+}