ed25519: Use ed25519::Signature from upstream crate

Sources the `ed25519::Signature` type from RustCrypto `ed25519` crate:

<https://docs.rs/ed25519/latest/ed25519/struct.Signature.html>

Cargo.toml

@@ -16,11 +16,12 @@ autobenches = false
 circle-ci = { repository = "tendermint/signatory", branch = "develop" }
 
 [dependencies]
+ed25519 = { version = "0.1", optional = true, default-features = false }
 generic-array = { version = "0.12", optional = true, default-features = false }
 getrandom = { version = "0.1", optional = true, default-features = false }
 sha2 = { version = "0.8", optional = true, default-features = false }
 signature = { version = "0.2", default-features = false }
-zeroize = { version = "0.9", optional = true, default-features = false }
+zeroize = { version = "0.9", default-features = false }
 
 [dependencies.subtle-encoding]
 version = "0.3.6"
@@ -32,9 +33,8 @@ features = ["base64", "hex"]
 alloc = []
 default = ["encoding", "getrandom", "std"]
 digest = ["signature/digest"]
-ecdsa = ["generic-array", "zeroize"]
-ed25519 = ["zeroize"]
-encoding = ["subtle-encoding", "zeroize"]
+ecdsa = ["generic-array"]
+encoding = ["subtle-encoding"]
 pkcs8 = ["encoding"]
 std = ["alloc", "signature/std", "subtle-encoding/std"]
 test-vectors = []

signatory-ring/src/ed25519.rs

@@ -73,7 +73,7 @@ impl signatory::Verifier<Signature> for Verifier {
             &ring::signature::ED25519,
             untrusted::Input::from(self.0.as_bytes()),
             untrusted::Input::from(msg),
-            untrusted::Input::from(signature.as_bytes()),
+            untrusted::Input::from(signature.as_ref()),
         )
         .map_err(|_| Error::new())
     }

src/ed25519.rs

@@ -30,7 +30,6 @@
 
 mod public_key;
 mod seed;
-mod signature;
 
 #[cfg(feature = "test-vectors")]
 #[macro_use]
@@ -45,5 +44,7 @@ pub use self::test_vectors::TEST_VECTORS;
 pub use self::{
     public_key::{PublicKey, PUBLIC_KEY_SIZE},
     seed::{Seed, SEED_SIZE},
-    signature::{Signature, SIGNATURE_SIZE},
 };
+
+// Import `Signature` type from the `ed25519` crate
+pub use ::ed25519::{Signature, SIGNATURE_LENGTH as SIGNATURE_SIZE};