private static unsafe void Pbkdf2HmacSha256(ProtectedMemory password, byte *salt, int saltLength, long c, int dkLen, byte *result)
{
if (c < 1)
{
throw new ArgumentException("The count " + nameof(c) + " cannot be less than 1!");
}
const int digestLength = 0x20;
int blockCount = (int)Math.Ceiling((double)dkLen / digestLength);
int saltBufferLength = saltLength + sizeof(int);
IntPtr hSaltBuffer = Marshal.AllocHGlobal(saltBufferLength);
byte * saltBuffer = (byte *)hSaltBuffer;
Unsafe.CopyBlock(saltBuffer, salt, (uint)saltLength);
for (int i = 1; i <= blockCount; i++)
{
MarshalExtensions.WriteInt32BigEndian(saltBuffer + saltLength, i);
Sha256ProtectedCryptoProvider sha256 = new Sha256ProtectedCryptoProvider();
(IntPtr hU, _) = sha256.ComputeHmacUnsafe(password, saltBuffer, saltBufferLength);
Unsafe.CopyBlock(result + ((i - 1) * digestLength), (void *)hU, digestLength);
MarshalExtensions.ZeroFree(hU, digestLength);
for (long j = 1; j < c; j++)
{
(IntPtr hUi, _) = sha256.ComputeHmacUnsafe(password, saltBuffer, digestLength);
byte *ui = (byte *)hUi;
for (int k = 0; k < digestLength; k++)
{
(result + ((i - 1) * digestLength))[k] ^= ui[k];
}
MarshalExtensions.ZeroFree(hUi, digestLength);
}
}
MarshalExtensions.ZeroFree(hSaltBuffer, saltBufferLength);
}
private static unsafe void Sha256HmacTests2()
{
byte[] key = Encoding.UTF8.GetBytes("ABCD");
IntPtr hMessage = Marshal.AllocHGlobal(32 + sizeof(int));
byte[] message = new byte[] { 0x4c, 0x1e, 0x67, 0xcb, 0xa2, 0xc8, 0xf4, 0xac, 0xb0, 0x53, 0x7f, 0x93, 0xf, 0x91, 0x5d, 0xac, 0xd4, 0xac, 0xc5, 0x85, 0x76, 0x4f, 0xed, 0xea, 0xcb, 0x14, 0x70, 0x32, 0x27, 0xae, 0xef, 0x34, 0x0, 0x0, 0x0, 0x0 };
Marshal.Copy(message, 0, hMessage, message.Length);
fixed(byte *pKey = key)
{
byte *pMessage = (byte *)hMessage;
Sha256ProtectedCryptoProvider sha256 = new Sha256ProtectedCryptoProvider();
(IntPtr h, int l) = sha256.ComputeHmacUnsafe(pKey, 4, pMessage, 32 + sizeof(int));
Marshal.FreeHGlobal(h);
}
Marshal.FreeHGlobal(hMessage);
}