lighthouse/eth2/utils/bls/src/signature.rs

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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).
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#[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 {
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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 {
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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);
}
}
}