«
»

PBKDF2 – Pure Java Implementation

This entry was posted on 2012-11-29 23:10:17 and is filed under Cryptography, Java, Programming. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

Here’s my PBKDF2 implementation. It’s a clean-room implementation straight from RFC 2898. It passes all RFC 6070 test vectors (testing code included).

It’s pure java with no weird requirements or external libraries. It performs reasonably well compared to the stock Java implementation of PBKDF2WithHmacSHA1; sometimes it beats it, sometimes it doesn’t. I’m sure there are ways to optimize performance.

Anyway, enjoy…

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
/*
 * Copyright (c) 2012
 * Cole Barnes [cryptofreek{at}gmail{dot}com]
 * https://cryptofreek.org/
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 * -----------------------------------------------------------------------------
 *
 * This is a clean-room implementation of PBKDF2 using RFC 2898 as a reference.
 *
 * RFC 2898:
 * http://tools.ietf.org/html/rfc2898#section-5.2
 *
 * This code passes all RFC 6070 test vectors:
 * http://tools.ietf.org/html/rfc6070
 *
 * The function "nativeDerive()" is supplied as an example of the native Java
 * PBKDF2WithHmacSHA1 implementation.  It is used for benchmarking and
 * comparison only.
 *
 * The functions "fromHex()" and "toHex()" came from some message board
 * somewhere.  No license was included.
 *
 */
 
import java.io.ByteArrayOutputStream;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.security.spec.KeySpec;
import java.util.Formatter;
 
import javax.crypto.Mac;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.SecretKeySpec;
 
public class CPbkdf2
{
  /* START RFC 2898 IMPLEMENTATION */
  public static byte[] derive(String P, String S, int c, int dkLen)
  {
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
 
    try
    {
      int hLen = 20;
 
      if (dkLen > ((Math.pow(2, 32)) - 1) * hLen)
      {
        System.out.println("derived key too long");
      }
      else
      {
        int l = (int) Math.ceil((double) dkLen / (double) hLen);
        // int r = dkLen - (l-1)*hLen;
 
        for (int i = 1; i <= l; i++)
        {
          byte[] T = F(P, S, c, i);
          baos.write(T);
        }
      }
    }
    catch (Exception e)
    {
      e.printStackTrace();
    }
 
    byte[] baDerived = new byte[dkLen];
    System.arraycopy(baos.toByteArray(), 0, baDerived, 0, baDerived.length);
 
    return baDerived;
  }
 
  private static byte[] F(String P, String S, int c, int i) throws Exception
  {
    byte[] U_LAST = null;
    byte[] U_XOR = null;
 
    SecretKeySpec key = new SecretKeySpec(P.getBytes("UTF-8"), "HmacSHA1");
    Mac mac = Mac.getInstance(key.getAlgorithm());
    mac.init(key);
 
    for (int j = 0; j < c; j++)
    {
      if (j == 0)
      {
        byte[] baS = S.getBytes("UTF-8");
        byte[] baI = INT(i);
        byte[] baU = new byte[baS.length + baI.length];
 
        System.arraycopy(baS, 0, baU, 0, baS.length);
        System.arraycopy(baI, 0, baU, baS.length, baI.length);
 
        U_XOR = mac.doFinal(baU);
        U_LAST = U_XOR;
        mac.reset();
      }
      else
      {
        byte[] baU = mac.doFinal(U_LAST);
        mac.reset();
 
        for (int k = 0; k < U_XOR.length; k++)
        {
          U_XOR[k] = (byte) (U_XOR[k] ^ baU[k]);
        }
 
        U_LAST = baU;
      }
    }
 
    return U_XOR;
  }
 
  private static byte[] INT(int i)
  {
    ByteBuffer bb = ByteBuffer.allocate(4);
    bb.order(ByteOrder.BIG_ENDIAN);
    bb.putInt(i);
 
    return bb.array();
  }
  /* END RFC 2898 IMPLEMENTATION */
 
  /* START HELPER FUNCTIONS */
  private static String toHex(byte[] ba)
  {
    String strHex = null;
 
    if (ba != null)
    {
      StringBuilder sb = new StringBuilder(ba.length * 2);
      Formatter formatter = new Formatter(sb);
 
      for (byte b : ba)
      {
        formatter.format("%02x", b);
      }
 
      formatter.close();
      strHex = sb.toString().toLowerCase();
    }
 
    return strHex;
  }
 
  private static byte[] nativeDerive(String strPassword, String strSalt, int nIterations, int nKeyLen)
  {
    byte[] baDerived = null;
 
    try
    {
      SecretKeyFactory f = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
      KeySpec ks = new PBEKeySpec(strPassword.toCharArray(), strSalt.getBytes("UTF-8"), nIterations, nKeyLen * 8);
      SecretKey s = f.generateSecret(ks);
      baDerived = s.getEncoded();
    }
    catch (Exception e)
    {
      e.printStackTrace();
    }
 
    return baDerived;
  }
  /* END HELPER FUNCTIONS */
 
  public static void runTestVector(String P, String S, int c, int dkLen, String strExpectedDk)
  {
    System.out.println("Input:");
    System.out.println("  P = \"" + P + "\"");
    System.out.println("  S = \"" + S + "\"");
    System.out.println("  c = " + c);
    System.out.println("  dkLen = " + dkLen);
    System.out.println();
 
    long nStartDk = System.nanoTime();
    byte[] DK = derive(P, S, c, dkLen);
    long nStopDk = System.nanoTime();
     
    long nStartDkNative = System.nanoTime();
    byte[] DK_NATIVE = nativeDerive(P, S, c, dkLen);
    long nStopDkNative = System.nanoTime();
 
    System.out.println("Output:");
    System.out.println("  DK          = " + toHex(DK));
    System.out.println("  DK_NATIVE   = " + toHex(DK_NATIVE));
    System.out.println("  DK_EXPECTED = " + strExpectedDk.replaceAll(" ", ""));
    System.out.println();
 
    System.out.println("Duration [my implementation]:      " + (nStopDk - nStartDk) + " ns" );
    System.out.println("Duration [native implementation]:  " + (nStopDkNative - nStartDkNative) + " ns" );
     
    System.out.println("---------------------------------------------------------------");
    System.out.println();
  }
 
  public static void RFC6070()
  {
    runTestVector("password", "salt", 1, 20, "0c 60 c8 0f 96 1f 0e 71 f3 a9 b5 24 af 60 12 06 2f e0 37 a6");
    runTestVector("password", "salt", 2, 20, "ea 6c 01 4d c7 2d 6f 8c cd 1e d9 2a ce 1d 41 f0 d8 de 89 57");
    runTestVector("password", "salt", 4096, 20, "4b 00 79 01 b7 65 48 9a be ad 49 d9 26 f7 21 d0 65 a4 29 c1");
    runTestVector("password", "salt", 16777216, 20, "ee fe 3d 61 cd 4d a4 e4 e9 94 5b 3d 6b a2 15 8c 26 34 e9 84");
    runTestVector("passwordPASSWORDpassword", "saltSALTsaltSALTsaltSALTsaltSALTsalt", 4096, 25, "3d 2e ec 4f e4 1c 84 9b 80 c8 d8 36 62 c0 e4 4a 8b 29 1a 96 4c f2 f0 70 38");
    runTestVector("pass\0word", "sa\0lt", 4096, 16, "56 fa 6a a7 55 48 09 9d cc 37 d7 f0 34 25 e0 c3");
  }
 
  public static void main(String[] args)
  {
    RFC6070();
  }
}

2 Responses to “PBKDF2 – Pure Java Implementation”

  1. Roberto says:
    2014-01-29 at 22:28:32

    Excelent! It was a big help.

Leave a Reply