/// <summary>
/// Reset the DGCPrng instance
/// </summary>
public void Reset()
{
if (m_digestEngine != null)
{
m_digestEngine.Dispose();
m_digestEngine = null;
}
if (m_seedGenerator != null)
{
m_seedGenerator.Dispose();
m_seedGenerator = null;
}
m_digestEngine = GetDigest(m_digestType);
m_rngGenerator = new DGC(m_digestEngine);
if (m_stateSeed != null)
{
m_rngGenerator.Initialize(m_stateSeed);
}
else
{
m_seedGenerator = GetSeedGenerator(m_seedType);
m_rngGenerator.Initialize(m_seedGenerator.GetBytes((m_digestEngine.BlockSize * 2) + 8)); // 2 * block + counter (2*bsz+8)
}
m_rngGenerator.Generate(m_byteBuffer);
m_bufferIndex = 0;
}
private void DGCDRBGTest(byte[] Seed, byte[] Expected)
{
DGC rGen = new DGC(new SHA256());
byte[] output = new byte[32];
rGen.Update(Seed);
for (int i = 0; i != 1024; i++)
{
rGen.Generate(output);
}
if (Evaluate.AreEqual(Expected, output) == false)
{
throw new Exception("DGCDRBG: Values are not equal! Expected: " + HexConverter.ToString(output) + " Received: " + HexConverter.ToString(Expected));
}
}
/// <summary>
/// Fill an array with pseudo random bytes
/// </summary>
///
/// <param name="Output">Array to fill with random bytes</param>
public void GetBytes(byte[] Output)
{
lock (m_objLock)
{
if (m_byteBuffer.Length - m_bufferIndex < Output.Length)
{
int bufSize = m_byteBuffer.Length - m_bufferIndex;
// copy remaining bytes
Buffer.BlockCopy(m_byteBuffer, m_bufferIndex, Output, 0, bufSize);
int rem = Output.Length - bufSize;
while (rem > 0)
{
// fill buffer
m_rngGenerator.Generate(m_byteBuffer);
if (rem > m_byteBuffer.Length)
{
Buffer.BlockCopy(m_byteBuffer, 0, Output, bufSize, m_byteBuffer.Length);
bufSize += m_byteBuffer.Length;
rem -= m_byteBuffer.Length;
}
else
{
Buffer.BlockCopy(m_byteBuffer, 0, Output, bufSize, rem);
m_bufferIndex = rem;
rem = 0;
}
}
}
else
{
Buffer.BlockCopy(m_byteBuffer, m_bufferIndex, Output, 0, Output.Length);
m_bufferIndex += Output.Length;
}
}
}