public static ICryptoTransform GetDecryptor(byte SymAlgo, byte[] IV, byte[] SessionKey) { if (!IsValidAlgoCode(SymAlgo)) { throw new NotImplementedException("Algorithm not implemented"); } int KeySize = SymmetricAlgorithmTypes.GetKeySize(SymAlgo); int BlockSizeBits = SymmetricAlgorithmTypes.GetBlockSize(SymAlgo); if (IV == null) { IV = new byte[BlockSizeBits / 8]; // Set to all zeros by default } RijndaelManaged aes = new RijndaelManaged { KeySize = KeySize, BlockSize = BlockSizeBits, FeedbackSize = BlockSizeBits, Key = SessionKey, IV = IV, Mode = CipherMode.CFB, Padding = PaddingMode.None }; return(aes.CreateDecryptor()); }
public override void Parse(TreeBuilder tree) { base.Parse(tree); bool IsEncrypted = true; tree.SetBookMark(); var S2K = new S2K { S2KUsage = tree.ReadByte() }; if (S2K.S2KUsage == 254 || S2K.S2KUsage == 255) { S2K.SymAlgo = tree.ReadByte("Symmetric Algorithm", SymmetricAlgorithmTypes.Get); byte S2KSpecifier = tree.ReadByte("S2K Specifier", S2KTypes.Get); if (S2KSpecifier != S2KTypes.Salted && S2KSpecifier != S2KTypes.Simple && S2KSpecifier != S2KTypes.IteratedAndSalted) { //tree.AddCalculated("Invalid S2K", S2KSpecifier.ToString()); tree.AddCalculated("Unable to Process", S2KSpecifier.ToString(), ByteBlockType.CalculatedError); return; } S2K.HashAlgorithm = tree.ReadByte("Hash Algorithm", HashAlgorithmTypes.Get); if (S2KSpecifier == S2KTypes.Salted || S2KSpecifier == S2KTypes.IteratedAndSalted) { S2K.Salt = tree.ReadBytes("Salt", 8); if (S2KSpecifier == S2KTypes.IteratedAndSalted) { byte CodedCount = tree.ReadByte("Coded Iteration"); S2K.ByteCount = (16 + (CodedCount & 15)) << ((CodedCount >> 4) + 6); } } int BlockSizeBytes = SymmetricAlgorithmTypes.GetBlockSize(S2K.SymAlgo) / 8; S2K.IV = tree.ReadBytes("IV", BlockSizeBytes); } else { byte SymAlgo = S2K.S2KUsage; S2K.SymAlgo = SymAlgo; if (SymAlgo != 0) { tree.GoToBookMark(); tree.ReadByte("Symmetric Algorithm", SymmetricAlgorithmTypes.Get); int BlockSize = SymmetricAlgorithmTypes.GetBlockSize(SymAlgo) / 8; S2K.IV = tree.ReadBytes("IV", BlockSize); } else { IsEncrypted = false; } } PublicKeyAlgorithm.S2K = S2K; if (IsEncrypted) { byte[] Encrypted = tree.ReadBytes("Encrypted Secret Key"); PublicKeyAlgorithm.EncryptedPrivateKey = Encrypted; tree.CurrentBlock.ProcessBlock += ExtractPrivateKey; SecretKeyNode = tree.CurrentBlock; } else { byte[] ClearBytes = tree.ReadBytes("Unencrypted Secret Key"); var SecBlockClear = PublicKeyAlgorithm.SetPrivate(ClearBytes); tree.AddChild(PublicKeyAlgorithm.GetPrivateByteBlocks()); } }