Rename beacon_chain/ -> eth2/

eth2/utils/bls/src/signature.rs

@@ -0,0 +1,89 @@
+use super::ssz::{decode_ssz_list, Decodable, DecodeError, Encodable, SszStream};
+use super::{PublicKey, SecretKey};
+use bls_aggregates::Signature as RawSignature;
+
+/// A single BLS signature.
+///
+/// This struct is a wrapper upon a base type and provides helper functions (e.g., SSZ
+/// serialization).
+#[derive(Debug, PartialEq, Clone, Eq)]
+pub struct Signature(RawSignature);
+
+impl Signature {
+    /// Instantiate a new Signature from a message and a SecretKey.
+    pub fn new(msg: &[u8], sk: &SecretKey) -> Self {
+        Signature(RawSignature::new(msg, sk.as_raw()))
+    }
+
+    /// Instantiate a new Signature from a message and a SecretKey, where the message has already
+    /// been hashed.
+    pub fn new_hashed(msg_hashed: &[u8], sk: &SecretKey) -> Self {
+        Signature(RawSignature::new_hashed(msg_hashed, sk.as_raw()))
+    }
+
+    /// Verify the Signature against a PublicKey.
+    pub fn verify(&self, msg: &[u8], pk: &PublicKey) -> bool {
+        self.0.verify(msg, pk.as_raw())
+    }
+
+    /// Verify the Signature against a PublicKey, where the message has already been hashed.
+    pub fn verify_hashed(&self, msg_hash: &[u8], pk: &PublicKey) -> bool {
+        self.0.verify_hashed(msg_hash, pk.as_raw())
+    }
+
+    /// Returns the underlying signature.
+    pub fn as_raw(&self) -> &RawSignature {
+        &self.0
+    }
+
+    /// Returns a new empty signature.
+    pub fn empty_signature() -> Self {
+        let empty: Vec<u8> = vec![0; 97];
+        Signature(RawSignature::from_bytes(&empty).unwrap())
+    }
+}
+
+impl Encodable for Signature {
+    fn ssz_append(&self, s: &mut SszStream) {
+        s.append_vec(&self.0.as_bytes());
+    }
+}
+
+impl Decodable for Signature {
+    fn ssz_decode(bytes: &[u8], i: usize) -> Result<(Self, usize), DecodeError> {
+        let (sig_bytes, i) = decode_ssz_list(bytes, i)?;
+        let raw_sig = RawSignature::from_bytes(&sig_bytes).map_err(|_| DecodeError::TooShort)?;
+        Ok((Signature(raw_sig), i))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::super::ssz::ssz_encode;
+    use super::super::Keypair;
+    use super::*;
+
+    #[test]
+    pub fn test_ssz_round_trip() {
+        let keypair = Keypair::random();
+
+        let original = Signature::new(&[42, 42], &keypair.sk);
+
+        let bytes = ssz_encode(&original);
+        let (decoded, _) = Signature::ssz_decode(&bytes, 0).unwrap();
+
+        assert_eq!(original, decoded);
+    }
+
+    #[test]
+    pub fn test_empty_signature() {
+        let sig = Signature::empty_signature();
+
+        let sig_as_bytes: Vec<u8> = sig.as_raw().as_bytes();
+
+        assert_eq!(sig_as_bytes.len(), 97);
+        for one_byte in sig_as_bytes.iter() {
+            assert_eq!(*one_byte, 0);
+        }
+    }
+}