/// <summary>
/// Sign the provided message using a Verifiable Random Function (VRF)
/// and if the result is less than param threshold provide the proof.
/// </summary>
/// <param name="message">The raw bytes of the message to sign.</param>
/// <param name="keypair">The keypair for signing.</param>
/// <param name="threshold">Threshold (byte array, 16 bytes).</param>
/// <param name="result">VRF signature output & proof.</param>
/// <returns>True if VRF signature was successful (and result below threshold)</returns>
public static bool VrfSignIfLess(byte[] message,
SR25519Keypair keypair, byte[] threshold, out VrfSignResult result)
{
result = null;
if (threshold?.Length != Constants.SR25519_VRF_THRESHOLD_SIZE)
{
throw new SR25519VrfException(StringConstants.BadVrfTresholdSizeMessage);
}
var vrfOutputAndProof = new byte[
Constants.SR25519_VRF_OUTPUT_SIZE +
Constants.SR25519_VRF_PROOF_SIZE
];
var rc = Bindings.VrfSignIfLess(
vrfOutputAndProof,
keypair.GetBytes(),
message,
Convert.ToUInt64(message.Length),
threshold);
result = new VrfSignResult(rc, vrfOutputAndProof);
return(rc.Result == Sr25519SignatureResult.Ok && rc.IsLess);
}
/// <summary>
/// Soft derive a new keypair from an existing keypair.
/// </summary>
/// <param name="keypair">Input keypair.</param>
/// <param name="chainCodeHex">Chain code as hex string.</param>
/// <returns>SR25519Keypair</returns>
public static SR25519Keypair SoftDeriveKeypair(SR25519Keypair keypair, string chainCodeHex)
{
byte[] chainCodeBytes = Utils.HexStringToByteArray(chainCodeHex);
if (chainCodeBytes.Length != Constants.SR25519_CHAINCODE_SIZE)
{
throw new SR25519KeypairException(StringConstants.BadChaincodeSizeMessage);
}
var bytes = keypair.GetBytes();
var derived = new byte[Constants.SR25519_KEYPAIR_SIZE];
Bindings.DeriveKeypairSoft(derived, bytes, chainCodeBytes);
return(new SR25519Keypair(derived));
}