add serialize_uncompressed to GenericSignature

crypto/bls/src/generic_signature.rs

@@ -14,6 +14,9 @@ use tree_hash::TreeHash;
 /// The byte-length of a BLS signature when serialized in compressed form.
 pub const SIGNATURE_BYTES_LEN: usize = 96;
 
+/// The byte-length of a BLS signature when serialized in uncompressed form.
+pub const SIGNATURE_UNCOMPRESSED_BYTES_LEN: usize = 192;
+
 /// Represents the signature at infinity.
 pub const INFINITY_SIGNATURE: [u8; SIGNATURE_BYTES_LEN] = [
     0xc0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
@@ -31,6 +34,9 @@ pub trait TSignature<GenericPublicKey>: Sized + Clone {
     /// Serialize `self` as compressed bytes.
     fn serialize(&self) -> [u8; SIGNATURE_BYTES_LEN];
 
+    /// Serialize `self` as uncompressed bytes.
+    fn serialize_uncompressed(&self) -> [u8; SIGNATURE_UNCOMPRESSED_BYTES_LEN];
+
     /// Deserialize `self` from compressed bytes.
     fn deserialize(bytes: &[u8]) -> Result<Self, Error>;
 
@@ -115,6 +121,11 @@ where
         }
     }
 
+    /// Serialize `self` as compressed bytes.
+    pub fn serialize_uncompressed(&self) -> Option<[u8; SIGNATURE_UNCOMPRESSED_BYTES_LEN]> {
+        self.point.as_ref().map(|point| point.serialize_uncompressed())
+    }
+
     /// Deserialize `self` from compressed bytes.
     pub fn deserialize(bytes: &[u8]) -> Result<Self, Error> {
         let point = if bytes == &NONE_SIGNATURE[..] {

crypto/bls/src/impls/blst.rs

@@ -11,6 +11,7 @@ use crate::{
 pub use blst::min_pk as blst_core;
 use blst::{blst_scalar, BLST_ERROR};
 use rand::Rng;
+use crate::generic_signature::SIGNATURE_UNCOMPRESSED_BYTES_LEN;
 
 pub const DST: &[u8] = b"BLS_SIG_BLS12381G2_XMD:SHA-256_SSWU_RO_POP_";
 pub const RAND_BITS: usize = 64;
@@ -189,6 +190,10 @@ impl TSignature<blst_core::PublicKey> for blst_core::Signature {
         self.to_bytes()
     }
 
+    fn serialize_uncompressed(&self) -> [u8; SIGNATURE_UNCOMPRESSED_BYTES_LEN] {
+        self.serialize()
+    }
+
     fn deserialize(bytes: &[u8]) -> Result<Self, Error> {
         Self::from_bytes(bytes).map_err(Into::into)
     }

crypto/bls/src/impls/fake_crypto.rs

@@ -8,6 +8,7 @@ use crate::{
     generic_signature::{TSignature, SIGNATURE_BYTES_LEN},
     Error, Hash256, ZeroizeHash, INFINITY_PUBLIC_KEY, INFINITY_SIGNATURE,
 };
+use crate::generic_signature::SIGNATURE_UNCOMPRESSED_BYTES_LEN;
 
 /// Provides the externally-facing, core BLS types.
 pub mod types {
@@ -106,6 +107,12 @@ impl TSignature<PublicKey> for Signature {
         self.0
     }
 
+    fn serialize_uncompressed(&self) -> [u8; SIGNATURE_UNCOMPRESSED_BYTES_LEN] {
+        let mut ret = [0; SIGNATURE_UNCOMPRESSED_BYTES_LEN];
+        ret[0..SIGNATURE_BYTES_LEN].copy_from_slice(&self.0);
+        ret
+    }
+
     fn deserialize(bytes: &[u8]) -> Result<Self, Error> {
         let mut signature = Self::infinity();
         signature.0[..].copy_from_slice(&bytes[0..SIGNATURE_BYTES_LEN]);