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 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));
}
