Source for gnu.javax.crypto.sasl.srp.SRP

   1: /* SRP.java --
   2:    Copyright (C) 2003, 2006 Free Software Foundation, Inc.
   3: 
   4: This file is a part of GNU Classpath.
   5: 
   6: GNU Classpath is free software; you can redistribute it and/or modify
   7: it under the terms of the GNU General Public License as published by
   8: the Free Software Foundation; either version 2 of the License, or (at
   9: your option) any later version.
  10: 
  11: GNU Classpath is distributed in the hope that it will be useful, but
  12: WITHOUT ANY WARRANTY; without even the implied warranty of
  13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14: General Public License for more details.
  15: 
  16: You should have received a copy of the GNU General Public License
  17: along with GNU Classpath; if not, write to the Free Software
  18: Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
  19: USA
  20: 
  21: Linking this library statically or dynamically with other modules is
  22: making a combined work based on this library.  Thus, the terms and
  23: conditions of the GNU General Public License cover the whole
  24: combination.
  25: 
  26: As a special exception, the copyright holders of this library give you
  27: permission to link this library with independent modules to produce an
  28: executable, regardless of the license terms of these independent
  29: modules, and to copy and distribute the resulting executable under
  30: terms of your choice, provided that you also meet, for each linked
  31: independent module, the terms and conditions of the license of that
  32: module.  An independent module is a module which is not derived from
  33: or based on this library.  If you modify this library, you may extend
  34: this exception to your version of the library, but you are not
  35: obligated to do so.  If you do not wish to do so, delete this
  36: exception statement from your version.  */
  37: 
  38: 
  39: package gnu.javax.crypto.sasl.srp;
  40: 
  41: import gnu.java.security.hash.HashFactory;
  42: import gnu.java.security.hash.IMessageDigest;
  43: import gnu.java.security.util.Util;
  44: 
  45: import java.io.UnsupportedEncodingException;
  46: import java.math.BigInteger;
  47: import java.util.HashMap;
  48: 
  49: /**
  50:  * A Factory class that returns SRP Singletons that know all SRP-related
  51:  * mathematical computations and protocol-related operations for both the
  52:  * client- and server-sides.
  53:  */
  54: public final class SRP
  55: {
  56:   /** The map of already instantiated SRP algorithm instances. */
  57:   private static final HashMap algorithms = new HashMap();
  58:   private static final byte COLON = (byte) 0x3A;
  59:   /** The underlying message digest algorithm used for all SRP calculations. */
  60:   private IMessageDigest mda;
  61: 
  62:   /** Trivial private constructor to enforce Singleton pattern. */
  63:   private SRP(final IMessageDigest mda)
  64:   {
  65:     super();
  66: 
  67:     this.mda = mda;
  68:   }
  69: 
  70:   /**
  71:    * Returns an instance of this object that uses the designated message digest
  72:    * algorithm as its digest function.
  73:    *
  74:    * @return an instance of this object for the designated digest name.
  75:    */
  76:   public static synchronized SRP instance(String mdName)
  77:   {
  78:     if (mdName != null)
  79:       mdName = mdName.trim().toLowerCase();
  80:     if (mdName == null || mdName.equals(""))
  81:       mdName = SRPRegistry.SRP_DEFAULT_DIGEST_NAME;
  82:     SRP result = (SRP) algorithms.get(mdName);
  83:     if (result == null)
  84:       {
  85:         final IMessageDigest mda = HashFactory.getInstance(mdName);
  86:         result = new SRP(mda);
  87:         algorithms.put(mdName, result);
  88:       }
  89:     return result;
  90:   }
  91: 
  92:   private static final byte[] xor(final byte[] b1, final byte[] b2,
  93:                                   final int length)
  94:   {
  95:     final byte[] result = new byte[length];
  96:     for (int i = 0; i < length; ++i)
  97:       result[i] = (byte)(b1[i] ^ b2[i]);
  98:     return result;
  99:   }
 100: 
 101:   /** @return the message digest algorithm name used by this instance. */
 102:   public String getAlgorithm()
 103:   {
 104:     return mda.name();
 105:   }
 106: 
 107:   /**
 108:    * Returns a new instance of the SRP message digest algorithm --which is
 109:    * SHA-160 by default, but could be anything else provided the proper
 110:    * conditions as specified in the SRP specifications.
 111:    *
 112:    * @return a new instance of the underlying SRP message digest algorithm.
 113:    * @throws RuntimeException if the implementation of the message digest
 114:    *           algorithm does not support cloning.
 115:    */
 116:   public IMessageDigest newDigest()
 117:   {
 118:     return (IMessageDigest) mda.clone();
 119:   }
 120: 
 121:   /**
 122:    * Convenience method to return the result of digesting the designated input
 123:    * with a new instance of the SRP message digest algorithm.
 124:    *
 125:    * @param src some bytes to digest.
 126:    * @return the bytes constituting the result of digesting the designated input
 127:    *         with a new instance of the SRP message digest algorithm.
 128:    */
 129:   public byte[] digest(final byte[] src)
 130:   {
 131:     final IMessageDigest hash = (IMessageDigest) mda.clone();
 132:     hash.update(src, 0, src.length);
 133:     return hash.digest();
 134:   }
 135: 
 136:   /**
 137:    * Convenience method to return the result of digesting the designated input
 138:    * with a new instance of the SRP message digest algorithm.
 139:    *
 140:    * @param src a String whose bytes (using US-ASCII encoding) are to be
 141:    *          digested.
 142:    * @return the bytes constituting the result of digesting the designated input
 143:    *         with a new instance of the SRP message digest algorithm.
 144:    * @throws UnsupportedEncodingException if US-ASCII charset is not found.
 145:    */
 146:   public byte[] digest(final String src) throws UnsupportedEncodingException
 147:   {
 148:     return digest(src.getBytes("US-ASCII"));
 149:   }
 150: 
 151:   /**
 152:    * Convenience method to XOR N bytes from two arrays; N being the output size
 153:    * of the SRP message digest algorithm.
 154:    *
 155:    * @param a the first byte array.
 156:    * @param b the second one.
 157:    * @return N bytes which are the result of the XOR operations on the first N
 158:    *         bytes from the designated arrays. N is the size of the SRP message
 159:    *         digest algorithm; eg. 20 for SHA-160.
 160:    */
 161:   public byte[] xor(final byte[] a, final byte[] b)
 162:   {
 163:     return xor(a, b, mda.hashSize());
 164:   }
 165: 
 166:   public byte[] generateM1(final BigInteger N, final BigInteger g,
 167:                            final String U, final byte[] s, final BigInteger A,
 168:                            final BigInteger B, final byte[] K, final String I,
 169:                            final String L, final byte[] cn, final byte[] cCB)
 170:       throws UnsupportedEncodingException
 171:   {
 172:     final IMessageDigest hash = (IMessageDigest) mda.clone();
 173:     byte[] b;
 174:     b = xor(digest(Util.trim(N)), digest(Util.trim(g)));
 175:     hash.update(b, 0, b.length);
 176:     b = digest(U);
 177:     hash.update(b, 0, b.length);
 178:     hash.update(s, 0, s.length);
 179:     b = Util.trim(A);
 180:     hash.update(b, 0, b.length);
 181:     b = Util.trim(B);
 182:     hash.update(b, 0, b.length);
 183:     hash.update(K, 0, K.length);
 184:     b = digest(I);
 185:     hash.update(b, 0, b.length);
 186:     b = digest(L);
 187:     hash.update(b, 0, b.length);
 188:     hash.update(cn, 0, cn.length);
 189:     hash.update(cCB, 0, cCB.length);
 190:     return hash.digest();
 191:   }
 192: 
 193:   public byte[] generateM2(final BigInteger A, final byte[] M1, final byte[] K,
 194:                            final String U, final String I, final String o,
 195:                            final byte[] sid, final int ttl, final byte[] cIV,
 196:                            final byte[] sIV, final byte[] sCB)
 197:       throws UnsupportedEncodingException
 198:   {
 199:     final IMessageDigest hash = (IMessageDigest) mda.clone();
 200:     byte[] b;
 201:     b = Util.trim(A);
 202:     hash.update(b, 0, b.length);
 203:     hash.update(M1, 0, M1.length);
 204:     hash.update(K, 0, K.length);
 205:     b = digest(U);
 206:     hash.update(b, 0, b.length);
 207:     b = digest(I);
 208:     hash.update(b, 0, b.length);
 209:     b = digest(o);
 210:     hash.update(b, 0, b.length);
 211:     hash.update(sid, 0, sid.length);
 212:     hash.update((byte)(ttl >>> 24));
 213:     hash.update((byte)(ttl >>> 16));
 214:     hash.update((byte)(ttl >>> 8));
 215:     hash.update((byte) ttl);
 216:     hash.update(cIV, 0, cIV.length);
 217:     hash.update(sIV, 0, sIV.length);
 218:     hash.update(sCB, 0, sCB.length);
 219:     return hash.digest();
 220:   }
 221: 
 222:   public byte[] generateKn(final byte[] K, final byte[] cn, final byte[] sn)
 223:   {
 224:     final IMessageDigest hash = (IMessageDigest) mda.clone();
 225:     hash.update(K, 0, K.length);
 226:     hash.update(cn, 0, cn.length);
 227:     hash.update(sn, 0, sn.length);
 228:     return hash.digest();
 229:   }
 230: 
 231:   public byte[] computeX(final byte[] s, final String user,
 232:                          final String password)
 233:       throws UnsupportedEncodingException
 234:   {
 235:     return computeX(s, user.getBytes("US-ASCII"), password.getBytes("US-ASCII"));
 236:   }
 237: 
 238:   public byte[] computeX(final byte[] s, final String user, final byte[] p)
 239:       throws UnsupportedEncodingException
 240:   {
 241:     return computeX(s, user.getBytes("US-ASCII"), p);
 242:   }
 243: 
 244:   private byte[] computeX(final byte[] s, final byte[] user, final byte[] p)
 245:   {
 246:     final IMessageDigest hash = (IMessageDigest) mda.clone();
 247:     hash.update(user, 0, user.length);
 248:     hash.update(COLON);
 249:     hash.update(p, 0, p.length);
 250:     final byte[] up = hash.digest();
 251:     hash.update(s, 0, s.length);
 252:     hash.update(up, 0, up.length);
 253:     return hash.digest();
 254:   }
 255: }