Org.BouncyCastle.Bcpg.SignatureSubpacketsParser.ReadPacket C# (CSharp) Method

		public SignatureSubpacket ReadPacket()
		{
			int l = input.ReadByte();
			if (l < 0)
				return null;

			int bodyLen = 0;
			if (l < 192)
			{
				bodyLen = l;
			}
			else if (l <= 223)
			{
				bodyLen = ((l - 192) << 8) + (input.ReadByte()) + 192;
			}
			else if (l == 255)
			{
				bodyLen = (input.ReadByte() << 24) | (input.ReadByte() << 16)
					|  (input.ReadByte() << 8)  | input.ReadByte();
			}
			else
			{
				// TODO Error?
			}

			int tag = input.ReadByte();
			if (tag < 0)
				throw new EndOfStreamException("unexpected EOF reading signature sub packet");

			byte[] data = new byte[bodyLen - 1];
			if (Streams.ReadFully(input, data) < data.Length)
				throw new EndOfStreamException();

			bool isCritical = ((tag & 0x80) != 0);
			SignatureSubpacketTag type = (SignatureSubpacketTag)(tag & 0x7f);
			switch (type)
			{
				case SignatureSubpacketTag.CreationTime:
					return new SignatureCreationTime(isCritical, data);
				case SignatureSubpacketTag.KeyExpireTime:
					return new KeyExpirationTime(isCritical, data);
				case SignatureSubpacketTag.ExpireTime:
					return new SignatureExpirationTime(isCritical, data);
				case SignatureSubpacketTag.Revocable:
					return new Revocable(isCritical, data);
				case SignatureSubpacketTag.Exportable:
					return new Exportable(isCritical, data);
				case SignatureSubpacketTag.IssuerKeyId:
					return new IssuerKeyId(isCritical, data);
				case SignatureSubpacketTag.TrustSig:
					return new TrustSignature(isCritical, data);
				case SignatureSubpacketTag.PreferredCompressionAlgorithms:
				case SignatureSubpacketTag.PreferredHashAlgorithms:
				case SignatureSubpacketTag.PreferredSymmetricAlgorithms:
					return new PreferredAlgorithms(type, isCritical, data);
				case SignatureSubpacketTag.KeyFlags:
					return new KeyFlags(isCritical, data);
				case SignatureSubpacketTag.PrimaryUserId:
					return new PrimaryUserId(isCritical, data);
				case SignatureSubpacketTag.SignerUserId:
					return new SignerUserId(isCritical, data);
				case SignatureSubpacketTag.NotationData:
					return new NotationData(isCritical, data);
			}
			return new SignatureSubpacket(type, isCritical, data);
		}
	}

        internal SignaturePacket(
            BcpgInputStream bcpgIn)
        {
            version = bcpgIn.ReadByte();

            if (version == 3 || version == 2)
            {
//                int l =
                bcpgIn.ReadByte();

                signatureType = bcpgIn.ReadByte();
                creationTime  = (((long)bcpgIn.ReadByte() << 24) | ((long)bcpgIn.ReadByte() << 16)
                                 | ((long)bcpgIn.ReadByte() << 8) | (uint)bcpgIn.ReadByte()) * 1000L;

                keyId |= (long)bcpgIn.ReadByte() << 56;
                keyId |= (long)bcpgIn.ReadByte() << 48;
                keyId |= (long)bcpgIn.ReadByte() << 40;
                keyId |= (long)bcpgIn.ReadByte() << 32;
                keyId |= (long)bcpgIn.ReadByte() << 24;
                keyId |= (long)bcpgIn.ReadByte() << 16;
                keyId |= (long)bcpgIn.ReadByte() << 8;
                keyId |= (uint)bcpgIn.ReadByte();

                keyAlgorithm  = (PublicKeyAlgorithmTag)bcpgIn.ReadByte();
                hashAlgorithm = (HashAlgorithmTag)bcpgIn.ReadByte();
            }
            else if (version == 4)
            {
                signatureType = bcpgIn.ReadByte();
                keyAlgorithm  = (PublicKeyAlgorithmTag)bcpgIn.ReadByte();
                hashAlgorithm = (HashAlgorithmTag)bcpgIn.ReadByte();

                int    hashedLength = (bcpgIn.ReadByte() << 8) | bcpgIn.ReadByte();
                byte[] hashed       = new byte[hashedLength];

                bcpgIn.ReadFully(hashed);

                //
                // read the signature sub packet data.
                //
                SignatureSubpacketsParser sIn = new SignatureSubpacketsParser(
                    new MemoryStream(hashed, false));

                ArrayList          v = new ArrayList();
                SignatureSubpacket sub;
                while ((sub = sIn.ReadPacket()) != null)
                {
                    v.Add(sub);
                }

                hashedData = new SignatureSubpacket[v.Count];

                for (int i = 0; i != hashedData.Length; i++)
                {
                    SignatureSubpacket p = (SignatureSubpacket)v[i];
                    if (p is IssuerKeyId)
                    {
                        keyId = ((IssuerKeyId)p).KeyId;
                    }
                    else if (p is SignatureCreationTime)
                    {
                        creationTime = DateTimeUtilities.DateTimeToUnixMs(
                            ((SignatureCreationTime)p).GetTime());
                    }

                    hashedData[i] = p;
                }

                int    unhashedLength = (bcpgIn.ReadByte() << 8) | bcpgIn.ReadByte();
                byte[] unhashed       = new byte[unhashedLength];

                bcpgIn.ReadFully(unhashed);

                sIn = new SignatureSubpacketsParser(new MemoryStream(unhashed, false));

                v.Clear();

                while ((sub = sIn.ReadPacket()) != null)
                {
                    v.Add(sub);
                }

                unhashedData = new SignatureSubpacket[v.Count];

                for (int i = 0; i != unhashedData.Length; i++)
                {
                    SignatureSubpacket p = (SignatureSubpacket)v[i];
                    if (p is IssuerKeyId)
                    {
                        keyId = ((IssuerKeyId)p).KeyId;
                    }
                    else if (p is SignatureCreationTime)
                    {
                        creationTime = DateTimeUtilities.DateTimeToUnixMs(
                            ((SignatureCreationTime)p).GetTime());
                    }

                    unhashedData[i] = (SignatureSubpacket)p;
                }
            }
            else
            {
                throw new Exception("unsupported version: " + version);
            }

            fingerprint = new byte[2];
            bcpgIn.ReadFully(fingerprint);

            switch (keyAlgorithm)
            {
            case PublicKeyAlgorithmTag.RsaGeneral:
            case PublicKeyAlgorithmTag.RsaSign:
                MPInteger v = new MPInteger(bcpgIn);
                signature = new MPInteger[] { v };
                break;

            case PublicKeyAlgorithmTag.Dsa:
                MPInteger r = new MPInteger(bcpgIn);
                MPInteger s = new MPInteger(bcpgIn);
                signature = new MPInteger[] { r, s };
                break;

            case PublicKeyAlgorithmTag.ElGamalEncrypt:     // yep, this really does happen sometimes.
            case PublicKeyAlgorithmTag.ElGamalGeneral:
                MPInteger p = new MPInteger(bcpgIn);
                MPInteger g = new MPInteger(bcpgIn);
                MPInteger y = new MPInteger(bcpgIn);
                signature = new MPInteger[] { p, g, y };
                break;

            default:
                throw new IOException("unknown signature key algorithm: " + keyAlgorithm);
            }
        }