public PasswordData(string password, byte[] keyFile)
{
if (!string.IsNullOrEmpty(password))
{
var utf8 = Encoding.UTF8.GetBytes(password);
_hash = BufferEx.GetHash(utf8);
}
if (keyFile != null)
{
if (_hash != null)
{
var current = _hash.Length;
Array.Resize(ref _hash, current + keyFile.Length);
Array.Copy(keyFile, 0, _hash,
current, keyFile.Length);
}
else
{
_hash = keyFile;
}
}
if (_hash == null)
{
throw new InvalidOperationException(
"At least password or key file must be provided");
}
_hash = BufferEx.GetHash(_hash);
}
public static Stream Decrypt(Stream source,
Headers headers, byte[] masterKey)
{
byte[] easKey;
using (var buffer = new MemoryStream())
{
var masterSeed = headers.MasterSeed;
buffer.Write(masterSeed, 0, masterSeed.Length);
buffer.Write(masterKey, 0, masterKey.Length);
easKey = BufferEx.GetHash(buffer.ToArray());
}
var eas = new AesManaged
{
KeySize = 256,
Key = BufferEx.Clone(easKey),
IV = BufferEx.Clone(headers.EncryptionIV)
};
Stream stream = new CryptoStream(source,
eas.CreateDecryptor(),
CryptoStreamMode.Read);
if (!VerifyStartBytes(headers, stream))
{
return(null);
}
stream = new HashedBlockStream(stream, true);
return(headers.Compression == Compressions.GZip
? new GZipInputStream(stream) : stream);
}
public void Verify()
{
Verify(HeaderFields.MasterSeed, 32,
"The length of the master key seed is invalid!");
Verify(HeaderFields.TransformSeed, 32,
"The length of the transform seed is invalid!");
Verify(HeaderFields.EncryptionIV, 16,
"The length of the encryption IV is invalid!");
Verify(HeaderFields.StreamStartBytes, 32,
"The length of the stream start bytes is invalid!");
var data = Verify(HeaderFields.CipherID, 16,
"The length of the cipher engine ID is invalid!");
if (!BufferEx.Equals(_easEngineId, data))
{
throw new FormatException(
"Only AES encryption is supported!");
}
data = Verify(HeaderFields.CompressionFlags, 4,
"The length of compression format is invalid!");
var compression = (Compressions)
BitConverter.ToChar(data, 0);
if (compression > Compressions.GZip)
{
throw new FormatException(
"Only no compression and GZip compression are supported!");
}
}
private bool ReadHashedBlock()
{
if (_eof)
{
return(false);
}
_position = 0;
if (_reader.ReadUInt32() != _bufferIndex)
{
throw new InvalidDataException();
}
_bufferIndex++;
var actualHash = _reader.ReadBytes(32);
if ((actualHash == null) || (actualHash.Length != 32))
{
throw new InvalidDataException();
}
var bufferSize = _reader.ReadInt32();
if (bufferSize < 0)
{
throw new InvalidDataException();
}
if (bufferSize == 0)
{
if (actualHash.Any(x => x != 0))
{
throw new InvalidDataException();
}
_eof = true;
_buffer = new byte[0];
return(false);
}
_buffer = _reader.ReadBytes(bufferSize);
if (_buffer == null || _buffer.Length != bufferSize)
{
throw new InvalidDataException();
}
var expectedHash = BufferEx.GetHash(_buffer);
if (!BufferEx.Equals(actualHash, expectedHash))
{
throw new InvalidDataException();
}
return(true);
}
private static bool VerifyStartBytes(
Headers headers, Stream stream)
{
var actual = new BinaryReader(stream)
.ReadBytes(32);
var expected = headers.StreamStartBytes;
return(BufferEx.Equals(actual, expected));
}
public byte[] TransformKey(byte[] transformSeed, int rounds)
{
var block = BufferEx.Clone(_hash);
var cipher = new AesEngine();
cipher.Init(true, new KeyParameter(transformSeed));
var aesEcb = SymmetricKeyAlgorithmProvider
.OpenAlgorithm(SymmetricAlgorithmNames.AesEcb);
var key = aesEcb.CreateSymmetricKey(
CryptographicBuffer.CreateFromByteArray(transformSeed));
for (int i = 0; i < rounds; i++)
{
cipher.ProcessBlock(block, 0, block, 0);
cipher.ProcessBlock(block, 16, block, 16);
}
return(BufferEx.GetHash(block));
}
public byte[] TransformKey(byte[] transformSeed, int rounds)
{
var block = BufferEx.Clone(_hash);
var aes = new AesManaged
{
KeySize = 256,
IV = new byte[16],
Key = transformSeed,
};
for (var i = 1; i <= rounds; i++)
{
// ECB mode is not available in Silverlight
// Always use a new encrytor to emulate ECB mode.
aes.CreateEncryptor().TransformBlock(
block, 0, 16, block, 0);
aes.CreateEncryptor().TransformBlock(
block, 16, 16, block, 16);
}
return(BufferEx.GetHash(block));
}
