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using System;
using System.Threading;
using Org.BouncyCastle.Crypto.Digests;
using Org.BouncyCastle.Crypto.Engines;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Crypto.Utilities;
namespace Org.BouncyCastle.Crypto.Generators
{
public class SCrypt
{
// TODO Validate arguments
public static byte[] Generate(byte[] P, byte[] S, int N, int r, int p, int dkLen)
{
return MFcrypt(P, S, N, r, p, dkLen);
}
private static byte[] MFcrypt(byte[] P, byte[] S, int N, int r, int p, int dkLen)
{
int MFLenBytes = r * 128;
byte[] bytes = SingleIterationPBKDF2(P, S, p * MFLenBytes);
uint[] B = null;
try
{
int BLen = bytes.Length >> 2;
B = new uint[BLen];
Pack.LE_To_UInt32(bytes, 0, B);
int MFLenWords = MFLenBytes >> 2;
for (int BOff = 0; BOff < BLen; BOff += MFLenWords)
{
// TODO These can be done in parallel threads
SMix(B, BOff, N, r);
}
Pack.UInt32_To_LE(B, bytes, 0);
return SingleIterationPBKDF2(P, bytes, dkLen);
}
finally
{
ClearAll(bytes, B);
}
}
private static byte[] SingleIterationPBKDF2(byte[] P, byte[] S, int dkLen)
{
PbeParametersGenerator pGen = new Pkcs5S2ParametersGenerator(new Sha256Digest());
pGen.Init(P, S, 1);
KeyParameter key = (KeyParameter)pGen.GenerateDerivedMacParameters(dkLen * 8);
return key.GetKey();
}
private static void SMix(uint[] B, int BOff, int N, int r)
{
int BCount = r * 32;
uint[] blockX1 = new uint[16];
uint[] blockX2 = new uint[16];
uint[] blockY = new uint[BCount];
uint[] X = new uint[BCount];
uint[][] V = new uint[N][];
try
{
Array.Copy(B, BOff, X, 0, BCount);
for (int i = 0; i < N; ++i)
{
V[i] = (uint[])X.Clone();
BlockMix(X, blockX1, blockX2, blockY, r);
}
uint mask = (uint)N - 1;
for (int i = 0; i < N; ++i)
{
uint j = X[BCount - 16] & mask;
Xor(X, V[j], 0, X);
BlockMix(X, blockX1, blockX2, blockY, r);
}
Array.Copy(X, 0, B, BOff, BCount);
}
finally
{
ClearAll(V);
ClearAll(X, blockX1, blockX2, blockY);
}
}
private static void BlockMix(uint[] B, uint[] X1, uint[] X2, uint[] Y, int r)
{
Array.Copy(B, B.Length - 16, X1, 0, 16);
int BOff = 0, YOff = 0, halfLen = B.Length >> 1;
for (int i = 2 * r; i > 0; --i)
{
Xor(X1, B, BOff, X2);
Salsa20Engine.SalsaCore(8, X2, X1);
Array.Copy(X1, 0, Y, YOff, 16);
YOff = halfLen + BOff - YOff;
BOff += 16;
}
Array.Copy(Y, 0, B, 0, Y.Length);
}
private static void Xor(uint[] a, uint[] b, int bOff, uint[] output)
{
for (int i = output.Length - 1; i >= 0; --i)
{
output[i] = a[i] ^ b[bOff + i];
}
}
private static void Clear(Array array)
{
if (array != null)
{
Array.Clear(array, 0, array.Length);
}
}
private static void ClearAll(params Array[] arrays)
{
foreach (Array array in arrays)
{
Clear(array);
}
}
}
}
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