Differing outputs between languages

[joshbenaron]

Hey,

I'm signing an identical message with the same key between this package and Rust's ed25519-dalek. The first 32ish bytes of both signatures are identical but the last bytes are not the same. Do you know why this could be?

[paulmillr]

No. Does it differ between different private keys?

[joshbenaron]

It differs with identical priv/pub keys, message

[paulmillr]

If you could provide a key/message pair, I will investigate this.

[joshbenaron]

Key = [ 232, 153, 76, 227, 11, 132, 39, 134, 89, 190, 9, 20, 251, 142, 65, 240, 252, 233, 70, 28, 233, 56, 14, 173, 81, 44, 139, 150, 139, 39, 200, 79, 88, 142, 42, 150, 88, 187, 51, 210, 155, 30, 26, 116, 229, 17, 165, 115, 112, 160, 123, 184, 142, 69, 194, 128, 197, 8, 92, 208, 49, 92, 178, 25, ]

Message = [ 110, 123, 209, 66, 178, 255, 153, 11, 45, 235, 189, 244, 42, 9, 152, 192, 181, 183, 40, 140, 216, 194, 141, 222, 128, 251, 237, 133, 207, 198, 131, 71, 242, 117, 246, 186, 189, 138, 117, 253, 31, 141, 117, 17, 179, 138, 224, 131 ]

[paulmillr]

your key is 64 bytes. ed25519 private keys are 32 bytes.

let sc = SecretKey::from_bytes(&Key[0..32]).unwrap();
let pubkey = PublicKey::from(&sc);
println!("SC {:?}", sc);
println!("SC/pub {:?}", hex::encode(pubkey.to_bytes()));
let kp = Keypair { public: pubkey, secret: sc };
    // Returns
    // 98FC99FD2869EFC7AA0743801620B8BD40DAA6DD798A8985BD43AE151E4C7C1A2937808FC199A76708FA046E06206F82B776EB4E05A426CB8F8B4ED4FB4AEC0F
    // Same as noble code:
    //   const privateKey = new Uint8Array(Key).slice(0, 32);
    //   const pub = await ed.getPublicKey(privateKey);
    //   console.log('PUB', Buffer.from(pub).toString('hex'));
    //   const signature = await ed.sign(new Uint8Array(Message), privateKey);
    //   console.log('SIG', signature, Buffer.from(signature).toString('hex'));
    println!("SIG {:?}", kp.sign(&Message));

[joshbenaron]

your key is 64 bytes

The first 32 bytes is the secret key and the second 32 is the public key. Very standard in crypto (as in cryptocurrency)

[paulmillr]

See my code -- the outputs match