Org.BouncyCastle.Crypto.Signers.DsaSigner.GenerateSignature C# (CSharp) Method

		public BigInteger[] GenerateSignature(
			byte[] message)
		{
			DsaParameters parameters = key.Parameters;
			BigInteger q = parameters.Q;
			BigInteger m = calculateE(q, message);
			BigInteger k;

			do
			{
				k = new BigInteger(q.BitLength, random);
			}
			while (k.CompareTo(q) >= 0);

			BigInteger r = parameters.G.ModPow(k, parameters.P).Mod(q);

			k = k.ModInverse(q).Multiply(
				m.Add(((DsaPrivateKeyParameters)key).X.Multiply(r)));

			BigInteger s = k.Mod(q);

			return new BigInteger[]{ r, s };
		}

        public static byte[] DoSignDsaSha1(IEnumerable <BufLen> bufs, I2PSigningPrivateKey key)
        {
            var sha = new Sha1Digest();

            foreach (var buf in bufs)
            {
                sha.BlockUpdate(buf.BaseArray, buf.BaseArrayOffset, buf.Length);
            }
            var hash = new byte[sha.GetDigestSize()];

            sha.DoFinal(hash, 0);

            var s = new Org.BouncyCastle.Crypto.Signers.DsaSigner();

            var dsaparams = new ParametersWithRandom(
                new DsaPrivateKeyParameters(
                    key.ToBigInteger(),
                    new DsaParameters(
                        I2PConstants.DsaP,
                        I2PConstants.DsaQ,
                        I2PConstants.DsaG)));

            s.Init(true, dsaparams);
            var sig    = s.GenerateSignature(hash);
            var result = new byte[40];

            var b1 = sig[0].ToByteArrayUnsigned();
            var b2 = sig[1].ToByteArrayUnsigned();

            // https://geti2p.net/en/docs/spec/common-structures#type_Signature
            // When a signature is composed of two elements (for example values R,S),
            // it is serialized by padding each element to length/2 with leading zeros if necessary.
            // All types are Big Endian, except for EdDSA, which is stored and transmitted in a Little Endian format.

            // Pad msb. Big endian.
            Array.Copy(b1, 0, result, 0 + 20 - b1.Length, b1.Length);
            Array.Copy(b2, 0, result, 20 + 20 - b2.Length, b2.Length);

            return(result);
        }