Novacoin/CryptoUtils.cs

   1 \feffusing System;
   2 using System.Security.Cryptography;
   3
   4 namespace Novacoin
   5 {
   6     public class CryptoUtils
   7     {
   8         public static byte[] PBKDF2_Sha256(int dklen, byte[] password, byte[] salt, int iterationCount)
   9         {
  10             using (var hmac = new HMACSHA256(password))
  11             {
  12                 int hashLength = hmac.HashSize / 8;
  13                 if ((hmac.HashSize & 7) != 0)
  14                     hashLength++;
  15                 int keyLength = dklen / hashLength;
  16                 if ((long)dklen > (0xFFFFFFFFL * hashLength) || dklen < 0)
  17                     throw new ArgumentOutOfRangeException("dklen");
  18                 if (dklen % hashLength != 0)
  19                     keyLength++;
  20                 byte[] extendedkey = new byte[salt.Length + 4];
  21                 Buffer.BlockCopy(salt, 0, extendedkey, 0, salt.Length);
  22                 using (var ms = new System.IO.MemoryStream())
  23                 {
  24                     for (int i = 0; i < keyLength; i++)
  25                     {
  26                         extendedkey[salt.Length] = (byte)(((i + 1) >> 24) & 0xFF);
  27                         extendedkey[salt.Length + 1] = (byte)(((i + 1) >> 16) & 0xFF);
  28                         extendedkey[salt.Length + 2] = (byte)(((i + 1) >> 8) & 0xFF);
  29                         extendedkey[salt.Length + 3] = (byte)(((i + 1)) & 0xFF);
  30                         byte[] u = hmac.ComputeHash(extendedkey);
  31                         Array.Clear(extendedkey, salt.Length, 4);
  32                         byte[] f = u;
  33                         for (int j = 1; j < iterationCount; j++)
  34                         {
  35                             u = hmac.ComputeHash(u);
  36                             for (int k = 0; k < f.Length; k++)
  37                             {
  38                                 f[k] ^= u[k];
  39                             }
  40                         }
  41                         ms.Write(f, 0, f.Length);
  42                         Array.Clear(u, 0, u.Length);
  43                         Array.Clear(f, 0, f.Length);
  44                     }
  45                     byte[] dk = new byte[dklen];
  46                     ms.Position = 0;
  47                     ms.Read(dk, 0, dklen);
  48                     ms.Position = 0;
  49                     for (long i = 0; i < ms.Length; i++)
  50                     {
  51                         ms.WriteByte(0);
  52                     }
  53                     Array.Clear(extendedkey, 0, extendedkey.Length);
  54                     return dk;
  55                 }
  56             }
  57         }
  58     }
  59 }