/// <summary>
/// Run the Inverse ThreeFish transform on a block of bytes, recovering the original length.
/// Padding assumed to be always applied using System.Security.Cryptography.PaddingMode.ANSIX923 mode.
/// </summary>
/// <param name="data">The data to be untransformed. Cannot be null or empty. Must be length which is a multiple of 32.</param>
/// <param name="key">The key byte array against which the data was originally transformed. Cannot be null and must be length 32.</param>
/// <param name="tweak">[OPTIONAL] The tweak used during the original ThreeFish transform. Must be of length less than/equal to 16 bytes. Default = Null (no tweak)</param>
/// <returns>The resulting transformed data in a byte array. The length of the resulting array will be shorter than the input array.</returns>
static byte[] InvThreeFishBytes(int wordwidth, byte[] data, byte[] key, byte[] tweak = null)
{
int BYTEWIDTH = wordwidth * 8;
if (data == null || data.Length % BYTEWIDTH != 0 || data.Length == 0)
{
throw new ArgumentNullException("data", "InvThreeFish256Bytes: data MUST be at a length which is a multiple of " +
BYTEWIDTH.ToString() + " and not null or empty");
}
if (key == null || key.Length != BYTEWIDTH)
{
throw new ArgumentException("key MUST be length " + BYTEWIDTH.ToString() + " and not null", "key");
}
if (tweak != null && tweak.Length > 16)
{
throw new ArgumentException("tweak MUST not exceed length 16", "tweak");
}
int totalBlocks = data.Length / BYTEWIDTH;
UInt64[] localKey = new UInt64[wordwidth];
Buffer.BlockCopy(key, 0, localKey, 0, key.Length);
UInt64[] localTweak = new UInt64[] { 0, 0 };
if (tweak != null)
{
Buffer.BlockCopy(tweak, 0, localTweak, 0, tweak.Length);
}
byte[] interimResult = new byte[Buffer.ByteLength(data)];
UInt64[] tempData = new UInt64[wordwidth];
for (int block = 0; block < totalBlocks; block++)
{
Buffer.BlockCopy(data, block * BYTEWIDTH, tempData, 0, BYTEWIDTH);
//InvThreeFish256Internal(tempData, localKey, localTweak, ref tempData);
ThreeFishCore.InvProcess256(tempData, localKey, localTweak, tempData);
Buffer.BlockCopy(tempData, 0, interimResult, block * BYTEWIDTH, BYTEWIDTH);
}
SkeinCore.ClearQWords(ref tempData[0], tempData.Length);
SkeinCore.ClearQWords(ref localKey[0], localKey.Length);
SkeinCore.ClearQWords(ref localTweak[0], localTweak.Length);
// not going to do any error checking (besides the obvious) that could give away information.
byte finalPaddingLength = interimResult[interimResult.GetUpperBound(0)];
byte[] finalResult = new byte[data.Length - finalPaddingLength];
Buffer.BlockCopy(interimResult, 0, finalResult, 0, finalResult.Length);
SkeinCore.ClearBytes(ref interimResult[0], interimResult.Length);
//System.GC.Collect();
return(finalResult);
}
/// <summary>
/// Run the ThreeFish transform on a block of bytes of arbitrarty length.
/// Padding is always applied using System.Security.Cryptography.PaddingMode.ANSIX923 mode.
/// </summary>
/// <param name="data">The data to be transformed. Cannot be null or empty.</param>
/// <param name="key">The key byte array against which to transform the data. Cannot be null and must be length 32.</param>
/// <param name="tweak">[OPTIONAL] The tweak used during the ThreeFish transform. Must be of length less than/equal to 16 bytes. Default = Null (no tweak)</param>
/// <returns>The resulting transformed data in a byte array. The length of the resulting array will be longer than the input array.</returns>
static byte[] ThreeFishBytes(int wordwidth, byte[] data, byte[] key, byte[] tweak = null)
{
int BYTEWIDTH = wordwidth * 8;
if (data == null || data.Length < 1)
{
throw new ArgumentNullException("data", "data MUST be at least length 1 and not null");
}
if (key == null || key.Length != BYTEWIDTH)
{
throw new ArgumentException("key MUST be length " + BYTEWIDTH.ToString() + " and not null", "key");
}
if (tweak != null && tweak.Length > 16)
{
throw new ArgumentException("tweak MUST not exceed length 16", "tweak");
}
int totalBlocks = (int)Math.Ceiling((double)data.Length / BYTEWIDTH);
byte paddingLength = (byte)(BYTEWIDTH - (data.Length % BYTEWIDTH));
if (paddingLength == 0 || paddingLength == BYTEWIDTH)
{
totalBlocks++;
paddingLength = (byte)BYTEWIDTH;
}
byte[] localLastData = new byte[BYTEWIDTH];
if (totalBlocks == 1)
{
Buffer.BlockCopy(data, 0, localLastData, 0, data.Length);
}
else
if (data.Length % BYTEWIDTH != 0)
{
Buffer.BlockCopy(data, (totalBlocks - 1) * BYTEWIDTH, localLastData, 0, data.Length % BYTEWIDTH);
}
localLastData[localLastData.GetUpperBound(0)] = paddingLength;
UInt64[] localKey = new UInt64[wordwidth];
Buffer.BlockCopy(key, 0, localKey, 0, key.Length);
UInt64[] localTweak = new UInt64[] { 0, 0 };
if (tweak != null)
{
Buffer.BlockCopy(tweak, 0, localTweak, 0, tweak.Length);
}
byte[] finalResult = new byte[totalBlocks * BYTEWIDTH];
UInt64[] tempData = new UInt64[wordwidth];
for (int block = 0; block < totalBlocks; block++)
{
if (block + 1 == totalBlocks)
{
Buffer.BlockCopy(localLastData, 0, tempData, 0, BYTEWIDTH);
}
else
{
Buffer.BlockCopy(data, block * BYTEWIDTH, tempData, 0, BYTEWIDTH);
}
Skein.ThreeFishCore.Process256(tempData, localKey, localTweak, false, tempData);
Buffer.BlockCopy(tempData, 0, finalResult, block * BYTEWIDTH, BYTEWIDTH);
}
SkeinCore.ClearQWords(ref tempData[0], tempData.Length);
SkeinCore.ClearBytes(ref localLastData[0], localLastData.Length);
SkeinCore.ClearQWords(ref localKey[0], localKey.Length);
SkeinCore.ClearQWords(ref localTweak[0], localTweak.Length);
//System.GC.Collect();
return(finalResult);
}