public EthECDSASignature Sign(string contract, string makerAddress, string makerToken, string takerToken, string makerAmount, string takerAmount, string expires, string nonce) { var plainData = new Object[] { contract, takerToken, BigInteger.Parse(takerAmount), makerToken, BigInteger.Parse(makerAmount), BigInteger.Parse(expires), BigInteger.Parse(nonce) }; var prms = new[] { new Parameter("address", 1), new Parameter("address", 1), new Parameter("uint256", 1), new Parameter("address", 1), new Parameter("uint256", 1), new Parameter("uint256", 1), new Parameter("uint256", 1) }; var data = SolidityPack(plainData, prms); var keystoreCrypto = new KeyStoreCrypto(); //for etherDelta its SHA256, for IDEX just change with SHA3 var hashed = keystoreCrypto.CalculateSha256Hash(data); var signer = new EthereumMessageSigner(); var newHash = signer.HashPrefixedMessage(hashed); var signatureRaw = signer.SignAndCalculateV(newHash, _userDataProvider.PrivateKey); var signature = EthECDSASignature.CreateStringSignature(signatureRaw); var probe = signer.EcRecover(hashed, signature); var ethEcdsa = MessageSigner.ExtractEcdsaSignature(signature); if (probe == makerAddress) { return(ethEcdsa); } //depending on usage, but it would be better to throw exc here if fails return(null); //throw new Exception("Signing failed"); }