Bouncy Castle C中的PBKDF2#

经过数小时的代码检查,我发现最简单的方法是在Pkcs5S2ParametersGenerator.cs中获取部分代码,并创建自己的类,当然它使用其他bouncycastleapi。这与dotnetcompact框架(windowsmobile)完美结合。这相当于Rfc2898DeriveBytes类,Dot-Net Compact Framework 2.0/3.5中没有该类。好吧,也许不是完全等价的,但做的工作:)

使用的PRF(伪随机函数)是HMAC-SHA1

http://www.bouncycastle.org/csharp/ BouncyCastle.Crypto.dll

然后用下面的代码创建新的类文件。

using System;
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Crypto.Digests;
using Org.BouncyCastle.Crypto.Macs;
using Org.BouncyCastle.Math;
using Org.BouncyCastle.Security;

namespace PBKDF2_PKCS5
{
    class PBKDF2
    {

        private readonly IMac hMac = new HMac(new Sha1Digest());

        private void F(
            byte[] P,
            byte[] S,
            int c,
            byte[] iBuf,
            byte[] outBytes,
            int outOff)
        {
            byte[] state = new byte[hMac.GetMacSize()];
            ICipherParameters param = new KeyParameter(P);

            hMac.Init(param);

            if (S != null)
            {
                hMac.BlockUpdate(S, 0, S.Length);
            }

            hMac.BlockUpdate(iBuf, 0, iBuf.Length);

            hMac.DoFinal(state, 0);

            Array.Copy(state, 0, outBytes, outOff, state.Length);

            for (int count = 1; count != c; count++)
            {
                hMac.Init(param);
                hMac.BlockUpdate(state, 0, state.Length);
                hMac.DoFinal(state, 0);

                for (int j = 0; j != state.Length; j++)
                {
                    outBytes[outOff + j] ^= state[j];
                }
            }
        }

        private void IntToOctet(
            byte[] Buffer,
            int i)
        {
            Buffer[0] = (byte)((uint)i >> 24);
            Buffer[1] = (byte)((uint)i >> 16);
            Buffer[2] = (byte)((uint)i >> 8);
            Buffer[3] = (byte)i;
        }

        // Use this function to retrieve a derived key.
        // dkLen is in octets, how much bytes you want when the function to return.
        // mPassword is the password converted to bytes.
        // mSalt is the salt converted to bytes
        // mIterationCount is the how much iterations you want to perform. 


        public byte[] GenerateDerivedKey(
            int dkLen,
            byte[] mPassword,
            byte[] mSalt,
            int mIterationCount
            )
        {
            int hLen = hMac.GetMacSize();
            int l = (dkLen + hLen - 1) / hLen;
            byte[] iBuf = new byte[4];
            byte[] outBytes = new byte[l * hLen];

            for (int i = 1; i <= l; i++)
            {
                IntToOctet(iBuf, i);

                F(mPassword, mSalt, mIterationCount, iBuf, outBytes, (i - 1) * hLen);
            }

        //By this time outBytes will contain the derived key + more bytes.
       // According to the PKCS #5 v2.0: Password-Based Cryptography Standard (www.truecrypt.org/docs/pkcs5v2-0.pdf) 
       // we have to "extract the first dkLen octets to produce a derived key".

       //I am creating a byte array with the size of dkLen and then using
       //Buffer.BlockCopy to copy ONLY the dkLen amount of bytes to it
       // And finally returning it :D

        byte[] output = new byte[dkLen];

        Buffer.BlockCopy(outBytes, 0, output, 0, dkLen);

        return output;
        }


    }
}

这是一个非常简单的示例,其中密码和salt由用户提供。

private void cmdDeriveKey_Click(object sender, EventArgs e)
        {
            byte[] salt = ASCIIEncoding.UTF8.GetBytes(txtSalt.Text);

            PBKDF2 passwordDerive = new PBKDF2();


      // I want the key to be used for AES-128, thus I want the derived key to be
      // 128 bits. Thus I will be using 128/8 = 16 for dkLen (Derived Key Length) . 
      //Similarly if you wanted a 256 bit key, dkLen would be 256/8 = 32. 

            byte[] result = passwordDerive.GenerateDerivedKey(16, ASCIIEncoding.UTF8.GetBytes(txtPassword.Text), salt, 1000);

           //result would now contain the derived key. Use it for whatever cryptographic purpose now :)
           //The following code is ONLY to show the derived key in a Textbox.

            string x = "";

            for (int i = 0; i < result.Length; i++)
            {
                x += result[i].ToString("X");
            }

            txtResult.Text = x;

        }

如何检查这是否正确? PBKDF2有一个在线javascript实现 http://anandam.name/pbkdf2/

如果有人得到不正确的结果,请报告:)

希望这能帮助别人:)

http://tools.ietf.org/html/draft-josefsson-pbkdf2-test-vectors-00

更新: RNGCryptoServiceProvider . 确保引用 System.Security.Cryptography 命名空间。

RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider();        

byte[] salt = new byte[16];

rng.GetBytes(salt);

我自己也有这个问题,找到了更直接的方法。至少从BouncyCastle1.7开始,您可以这样做(在VB中使用Org.BouncyCastle.Crypto):

Dim bcKeyDer As New Generators.Pkcs5S2ParametersGenerator()
bcKeyDer.Init(password, salt, keyIterations)
Dim bcparam As Parameters.KeyParameter = bcKeyDer.GenerateDerivedParameters("aes256", 256)
Dim key1() As Byte = bcparam.GetKey()

我已经用.Net的System.Security.Cryptography测试过了,而且还可以!