Add a function to only blind the public key

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ed25519-compact"
-version = "1.0.10"
+version = "1.0.11"
 authors = ["Frank Denis <github@pureftpd.org>"]
 edition = "2018"
 description = "A small, self-contained, wasm-friendly Ed25519 implementation"

src/ed25519.rs

@@ -673,6 +673,20 @@ mod blind_keys {
  }
  }
 
+ impl PublicKey {
+ /// Returns a blind version of the public key.
+ pub fn blind(&self, blind: &Blind) -> Result<BlindPublicKey, Error> {
+ let (blind_factor, _prefix2) = {
+ let hash_output = sha512::Hash::hash(&blind[..]);
+ KeyPair::split(&hash_output, true, false)
+ };
+ let pk_p3 = GeP3::from_bytes_vartime(&self.0).ok_or(Error::InvalidPublicKey)?;
+ Ok(BlindPublicKey(
+ ge_scalarmult(&blind_factor, &pk_p3).to_bytes(),
+ ))
+ }
+ }
+
  impl KeyPair {
  /// Returns a blind version of the key pair.
  pub fn blind(&self, blind: &Blind) -> BlindKeyPair {