gistfile1.cs

static byte[] Sign(string message, byte[] secretKey)
    {
        byte[] messageBuffer = UTF8Encoding.UTF8.GetBytes(message);
 
        var signedMessage = new byte[CryptoSign.Bytes + messageBuffer.Length];
 
        int smlen;
        CryptoSign.Sign(signedMessage, 0, out smlen, messageBuffer, 0, messageBuffer.Length, secretKey);
 
        if (smlen != signedMessage.Length)
        {
            var buffer = new byte[smlen];
            Array.Copy(signedMessage, 0, buffer, 0, smlen);
            return buffer;
        }
        else
        {
            return signedMessage;
        }
    }
 
    static string Verify(byte[] signedMessage, byte[] publicKey)
    {
        var buffer = new byte[signedMessage.Length];
        int mlen;
        if (CryptoSign.Open(buffer, 0, out mlen, signedMessage, 0, signedMessage.Length, publicKey)
                != 0)
        {
            throw new ArgumentException("Could not verify message!");
        }
        char[] messageBuffer = UTF8Encoding.UTF8.GetChars(buffer, 0, mlen);
        return new string(messageBuffer);
    }