/// <summary>
/// Encrypt a block of bytes using offset parameters.
/// <para>Encrypts one block of bytes at the designated offsets.
/// Initialize(bool, KeyParams) must be called before this method can be used.</para>
/// </summary>
///
/// <param name="Input">The input array of plain text bytes</param>
/// <param name="InOffset">Starting offset within the input array</param>
/// <param name="Output">The output array of encrypted bytes</param>
/// <param name="OutOffset">Starting offset within the output array</param>
public void EncryptBlock(byte[] Input, int InOffset, byte[] Output, int OutOffset)
{
// xor iv and input
IntUtils.XORBLK(Input, InOffset, m_cbcIv, 0, m_cbcIv.Length);
// encrypt iv
m_blockCipher.EncryptBlock(m_cbcIv, 0, Output, OutOffset);
// copy output to iv
Buffer.BlockCopy(Output, OutOffset, m_cbcIv, 0, m_blockSize);
}
/// <summary>
/// Decrypt a block of bytes with offset parameters.
/// <para>Decrypts one block of bytes at the designated offsets.
/// Initialize(bool, KeyParams) must be called before this method can be used.</para>
/// </summary>
///
/// <param name="Input">The input array of encrypted bytes</param>
/// <param name="InOffset">Starting offset within the Input array</param>
/// <param name="Output">The output array of decrypted bytes</param>
/// <param name="OutOffset">Starting offset within the Output array</param>
public void DecryptBlock(byte[] Input, int InOffset, byte[] Output, int OutOffset)
{
// copy input to temp iv
Buffer.BlockCopy(Input, InOffset, m_cbcNextIv, 0, m_blockSize);
// decrypt input
m_blockCipher.DecryptBlock(Input, InOffset, Output, OutOffset);
// xor output and iv
IntUtils.XORBLK(m_cbcIv, 0, Output, OutOffset, m_cbcIv.Length);
// copy forward iv
Buffer.BlockCopy(m_cbcNextIv, 0, m_cbcIv, 0, m_cbcIv.Length);
}
private void ProcessDecrypt(byte[] Input, int InOffset, byte[] Output, int OutOffset, byte[] Vector)
{
byte[] nextIv = new byte[Vector.Length];
// copy input to temp iv
Buffer.BlockCopy(Input, InOffset, nextIv, 0, m_blockSize);
// decrypt input
m_blockCipher.DecryptBlock(Input, InOffset, Output, OutOffset);
// xor output and iv
IntUtils.XORBLK(Vector, 0, Output, OutOffset, Vector.Length);
// copy forward iv
Buffer.BlockCopy(nextIv, 0, Vector, 0, m_blockSize);
}
private void TransformParallel(byte[] Input, int InOffset, byte[] Output, int OutOffset, int Length)
{
int outSize = Length;
// parallel CTR processing //
int cnkSize = m_parallelBlockSize / m_processorCount;
int rndSize = cnkSize * m_processorCount;
int subSize = cnkSize / m_blockSize;
byte[] tmpCtr = new byte[m_ctrVector.Length];
// create random, and xor to output in parallel
System.Threading.Tasks.Parallel.For(0, m_processorCount, ParallelOption, i =>
{
// thread level counter
byte[] thdCtr = new byte[m_ctrVector.Length];
// offset counter by chunk size / block size
thdCtr = Increase(m_ctrVector, subSize * i);
// create random at offset position
Generate(Output, OutOffset + (i * cnkSize), cnkSize, thdCtr);
// xor with input at offset
IntUtils.XORBLK(Input, InOffset + (i * cnkSize), Output, OutOffset + (i * cnkSize), cnkSize);
// store last counter
if (i == m_processorCount - 1)
{
Buffer.BlockCopy(thdCtr, 0, tmpCtr, 0, tmpCtr.Length);
}
});
// copy the last counter position to class variable
Buffer.BlockCopy(tmpCtr, 0, m_ctrVector, 0, m_ctrVector.Length);
// last block processing
int alnSze = cnkSize * m_processorCount;
if (alnSze < outSize)
{
int fnlSize = outSize % alnSze;
Generate(Output, alnSze, fnlSize, m_ctrVector);
for (int i = alnSze; i < outSize; i++)
{
Output[i] ^= Input[i];
}
}
}
private void Process(byte[] Input, int InOffset, byte[] Output, int OutOffset, int Length)
{
int prcSze = (Length >= Input.Length - InOffset) && Length >= Output.Length - OutOffset ? IntUtils.Min(Input.Length - InOffset, Output.Length - OutOffset) : Length;
if (!m_isParallel || prcSze < m_parallelBlockSize)
{
// generate random
Generate(prcSze, m_ctrVector, Output, OutOffset);
// output is input xor with random
int sze = prcSze - (prcSze % BLOCK_SIZE);
if (sze != 0)
{
IntUtils.XORBLK(Input, InOffset, Output, OutOffset, sze);
}
// get the remaining bytes
if (sze != prcSze)
{
for (int i = sze; i < prcSze; i++)
{
Output[i + OutOffset] ^= Input[i + InOffset];
}
}
}
else
{
// parallel CTR processing //
int cnkSize = (prcSze / BLOCK_SIZE / m_processorCount) * BLOCK_SIZE;
int rndSize = cnkSize * m_processorCount;
int subSize = (cnkSize / BLOCK_SIZE);
uint[] tmpCtr = new uint[m_ctrVector.Length];
// create random, and xor to output in parallel
System.Threading.Tasks.Parallel.For(0, m_processorCount, i =>
{
// thread level counter
uint[] thdCtr = new uint[m_ctrVector.Length];
// offset counter by chunk size / block size
thdCtr = Increase(m_ctrVector, subSize * i);
// create random at offset position
this.Generate(cnkSize, thdCtr, Output, OutOffset + (i * cnkSize));
// xor with input at offset
IntUtils.XORBLK(Input, InOffset + (i * cnkSize), Output, OutOffset + (i * cnkSize), cnkSize);
// store last counter
if (i == m_processorCount - 1)
{
Array.Copy(thdCtr, 0, tmpCtr, 0, thdCtr.Length);
}
});
// last block processing
if (rndSize < prcSze)
{
int fnlSize = prcSze % rndSize;
Generate(fnlSize, tmpCtr, Output, rndSize);
for (int i = 0; i < fnlSize; ++i)
{
Output[i + OutOffset + rndSize] ^= (byte)(Input[i + InOffset + rndSize]);
}
}
// copy the last counter position to class variable
Array.Copy(tmpCtr, 0, m_ctrVector, 0, m_ctrVector.Length);
}
}
