public static byte[] Decrypt(byte[] bytes, Dictionary <ulong, Smb2CryptoInfo> cryptoInfoTable, Smb2Role role)
{
// Client: If the size of the message received from the server is not greater than the size of SMB2 TRANSFORM_HEADER as specified, the client MUST discard the message.
// Server: If the size of the message received from the client is not greater than the size of the SMB2 TRANSFORM_HEADER, the server MUST disconnect the connection.
int minimumLength = Marshal.SizeOf(typeof(Transform_Header));
if (bytes.Length < minimumLength)
{
throw new InvalidOperationException(
String.Format(
"Too less data for encrypted message. Expected length more than {0}, actual {1}.",
minimumLength,
bytes.Length
)
);
}
Transform_Header transformHeader = Smb2Utility.UnmarshalStructure <Transform_Header>(bytes);
// Client: If the Flags/EncryptionAlgorithm in the SMB2 TRANSFORM_HEADER is not 0x0001, the client MUST discard the message.
// Server: If the Flags/EncryptionAlgorithm in the SMB2 TRANSFORM_HEADER is not 0x0001, the server MUST disconnect the connection.
if (transformHeader.Flags != TransformHeaderFlags.Encrypted)
{
throw new InvalidOperationException(
String.Format(
"Flags/EncryptionAlgorithm field is invalid for encrypted message. Expected value 0x0001, actual {0}.",
(ushort)transformHeader.Flags
)
);
}
if (transformHeader.SessionId == 0 || !cryptoInfoTable.ContainsKey(transformHeader.SessionId))
{
throw new InvalidOperationException("Invalid SessionId in TRANSFORM_HEADER.");
}
Smb2CryptoInfo cryptoInfo = cryptoInfoTable[transformHeader.SessionId];
using (var bcrypt = new BCryptAlgorithm("AES"))
{
int nonceLength = 0;
BCryptCipherMode mode = BCryptCipherMode.NotAvailable;
GetCryptoParams(cryptoInfo, CryptoOperationType.Decrypt, out mode, out nonceLength);
bcrypt.Mode = mode;
bcrypt.Key = role == Smb2Role.Server ? cryptoInfo.ServerInKey : cryptoInfo.ServerOutKey;
return(bcrypt.Decrypt(bytes.Skip(52).ToArray(), transformHeader.Nonce.ToByteArray().Take(nonceLength).ToArray(), bytes.Skip(20).Take(32).ToArray(), transformHeader.Signature));
}
}
public static byte[] Decrypt(byte[] bytes, Dictionary <ulong, Smb2CryptoInfo> cryptoInfoTable, Smb2Role role, out Transform_Header transformHeader)
{
var encryptedPacket = new Smb2EncryptedPacket();
int consumedLen;
int expectedLen;
encryptedPacket.FromBytes(bytes, out consumedLen, out expectedLen);
transformHeader = encryptedPacket.Header;
// For client: If the Flags/EncryptionAlgorithm in the SMB2 TRANSFORM_HEADER is not 0x0001, the client MUST discard the message.
// For server: If the Flags/EncryptionAlgorithm in the SMB2 TRANSFORM_HEADER is not 0x0001, the server MUST disconnect the connection.
if (transformHeader.Flags != TransformHeaderFlags.Encrypted)
{
throw new InvalidOperationException(
String.Format(
"Flags/EncryptionAlgorithm field is invalid for encrypted message. Expected value 0x0001, actual {0}.",
(ushort)transformHeader.Flags
)
);
}
if (transformHeader.SessionId == 0 || !cryptoInfoTable.ContainsKey(transformHeader.SessionId))
{
throw new InvalidOperationException("Invalid SessionId in TRANSFORM_HEADER.");
}
Smb2CryptoInfo cryptoInfo = cryptoInfoTable[transformHeader.SessionId];
using (var bcrypt = new BCryptAlgorithm("AES"))
{
int nonceLength = 0;
BCryptCipherMode mode = BCryptCipherMode.NotAvailable;
GetCryptoParams(cryptoInfo, CryptoOperationType.Decrypt, out mode, out nonceLength);
bcrypt.Mode = mode;
bcrypt.Key = role == Smb2Role.Server ? cryptoInfo.ServerInKey : cryptoInfo.ServerOutKey;
// Auth data is Transform_Header start from Nonce, excluding ProtocolId and Signature.
var authData = Smb2Utility.MarshalStructure(transformHeader).Skip((int)Marshal.OffsetOf <Transform_Header>("Nonce")).ToArray();
return(bcrypt.Decrypt(encryptedPacket.EncryptdData, transformHeader.Nonce.ToByteArray().Take(nonceLength).ToArray(), authData, transformHeader.Signature));
}
}
public static byte[] Decrypt(byte[] bytes, Dictionary <ulong, Smb2CryptoInfo> cryptoInfoTable, Smb2Role role)
{
Transform_Header transformHeader = Smb2Utility.UnmarshalStructure <Transform_Header>(bytes);
if (transformHeader.SessionId == 0 || !cryptoInfoTable.ContainsKey(transformHeader.SessionId))
{
throw new InvalidOperationException("Invalid SessionId in TRANSFORM_HEADER.");
}
Smb2CryptoInfo cryptoInfo = cryptoInfoTable[transformHeader.SessionId];
using (var bcrypt = new BCryptAlgorithm("AES"))
{
int nonceLength = 0;
BCryptCipherMode mode = BCryptCipherMode.NotAvailable;
GetCryptoParams(cryptoInfo, CryptoOperationType.Decrypt, out mode, out nonceLength);
bcrypt.Mode = mode;
bcrypt.Key = role == Smb2Role.Server ? cryptoInfo.ServerInKey : cryptoInfo.ServerOutKey;
return(bcrypt.Decrypt(bytes.Skip(52).ToArray(), transformHeader.Nonce.ToByteArray().Take(nonceLength).ToArray(), bytes.Skip(20).Take(32).ToArray(), transformHeader.Signature));
}
}