private byte[] GenerateRandom256()
{
if (this.GenerateRandom256Pre != null)
{
this.GenerateRandom256Pre(this, EventArgs.Empty);
}
byte[] pbCmp;
lock (m_oSyncRoot)
{
m_uCounter += 0x74D8B29E4D38E161UL; // Prime number
byte[] pbCounter = MemUtil.UInt64ToBytes(m_uCounter);
byte[] pbCsp = GetCspRandom();
byte[] pbPool = m_pbEntropyPool.ReadData();
int cbPool = pbPool.Length;
int cbCtr = pbCounter.Length;
int cbCsp = pbCsp.Length;
pbCmp = new byte[cbPool + cbCtr + cbCsp];
Array.Copy(pbPool, pbCmp, cbPool);
Array.Copy(pbCounter, 0, pbCmp, cbPool, cbCtr);
Array.Copy(pbCsp, 0, pbCmp, cbPool + cbCtr, cbCsp);
MemUtil.ZeroByteArray(pbCsp);
MemUtil.ZeroByteArray(pbPool);
m_uGeneratedBytesCount += 32;
}
byte[] pbRet = CryptoUtil.HashSha256(pbCmp);
MemUtil.ZeroByteArray(pbCmp);
return(pbRet);
}
private static void AddStrHash(Stream s, string str)
{
if (s == null)
{
Debug.Assert(false); return;
}
if (string.IsNullOrEmpty(str))
{
return;
}
byte[] pbUtf8 = StrUtil.Utf8.GetBytes(str);
byte[] pbHash = CryptoUtil.HashSha256(pbUtf8);
MemUtil.Write(s, pbHash);
}
/// <summary>
/// Construct a new cryptographically secure random stream object.
/// </summary>
/// <param name="a">Algorithm to use.</param>
/// <param name="pbKey">Initialization key. Must not be <c>null</c>
/// and must contain at least 1 byte.</param>
public CryptoRandomStream(CrsAlgorithm a, byte[] pbKey)
{
if (pbKey == null)
{
Debug.Assert(false); throw new ArgumentNullException("pbKey");
}
int cbKey = pbKey.Length;
if (cbKey <= 0)
{
Debug.Assert(false); // Need at least one byte
throw new ArgumentOutOfRangeException("pbKey");
}
m_crsAlgorithm = a;
if (a == CrsAlgorithm.ChaCha20)
{
byte[] pbKey32 = new byte[32];
byte[] pbIV12 = new byte[12];
using (SHA512Managed h = new SHA512Managed())
{
byte[] pbHash = h.ComputeHash(pbKey);
Array.Copy(pbHash, pbKey32, 32);
Array.Copy(pbHash, 32, pbIV12, 0, 12);
MemUtil.ZeroByteArray(pbHash);
}
m_chacha20 = new ChaCha20Cipher(pbKey32, pbIV12, true);
}
else if (a == CrsAlgorithm.Salsa20)
{
byte[] pbKey32 = CryptoUtil.HashSha256(pbKey);
byte[] pbIV8 = new byte[8] {
0xE8, 0x30, 0x09, 0x4B,
0x97, 0x20, 0x5D, 0x2A
}; // Unique constant
m_salsa20 = new Salsa20Cipher(pbKey32, pbIV8);
}
else if (a == CrsAlgorithm.ArcFourVariant)
{
// Fill the state linearly
m_pbState = new byte[256];
for (int w = 0; w < 256; ++w)
{
m_pbState[w] = (byte)w;
}
unchecked
{
byte j = 0, t;
int inxKey = 0;
for (int w = 0; w < 256; ++w) // Key setup
{
j += (byte)(m_pbState[w] + pbKey[inxKey]);
t = m_pbState[0]; // Swap entries
m_pbState[0] = m_pbState[j];
m_pbState[j] = t;
++inxKey;
if (inxKey >= cbKey)
{
inxKey = 0;
}
}
}
GetRandomBytes(512); // Increases security, see cryptanalysis
}
else // Unknown algorithm
{
Debug.Assert(false);
throw new ArgumentOutOfRangeException("a");
}
}
