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1: /* MessageDigest.java --- The message digest interface. 2: Copyright (C) 1999, 2002, 2003 Free Software Foundation, Inc. 3: 4: This file is 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, or (at your option) 9: 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; see the file COPYING. If not, write to the 18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19: 02110-1301 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: package java.security; 39: 40: import gnu.java.security.Engine; 41: 42: /** 43: * <p>This <code>MessageDigest</code> class provides applications the 44: * functionality of a message digest algorithm, such as <i>MD5</i> or <i>SHA</i>. 45: * Message digests are secure one-way hash functions that take arbitrary-sized 46: * data and output a fixed-length hash value.</p> 47: * 48: * <p>A <code>MessageDigest</code> object starts out initialized. The data is 49: * processed through it using the <code>update()</code> methods. At any point 50: * <code>reset()</code> can be called to reset the digest. Once all the data to 51: * be updated has been updated, one of the <code>digest()</code> methods should 52: * be called to complete the hash computation.</p> 53: * 54: * <p>The <code>digest()</code> method can be called <b>once</b> for a given 55: * number of updates. After <code>digest()</code> has been called, the 56: * <code>MessageDigest</code> object is <b>reset</b> to its initialized state. 57: * </p> 58: * 59: * <p>Implementations are free to implement the {@link Cloneable} interface. 60: * Client applications can test cloneability by attempting cloning and catching 61: * the {@link CloneNotSupportedException}: 62: * 63: * <pre> 64: * MessageDigest md = MessageDigest.getInstance("SHA"); 65: * try 66: * { 67: * md.update(toChapter1); 68: * MessageDigest tc1 = md.clone(); 69: * byte[] toChapter1Digest = tc1.digest(); 70: * md.update(toChapter2); 71: * // ... 72: * } 73: * catch (CloneNotSupportedException x) 74: * { 75: * throw new DigestException("couldn't make digest of partial content"); 76: * } 77: * </pre> 78: * 79: * <p>Note that if a given implementation is not cloneable, it is still possible 80: * to compute intermediate digests by instantiating several instances, if the 81: * number of digests is known in advance.</p> 82: * 83: * <p>Note that this class is abstract and extends from {@link MessageDigestSpi} 84: * for historical reasons. Application developers should only take notice of the 85: * methods defined in this <code>MessageDigest</code> class; all the methods in 86: * the superclass are intended for cryptographic service providers who wish to 87: * supply their own implementations of message digest algorithms.</p> 88: * 89: * @see MessageDigestSpi 90: * @see Provider 91: * @since JDK 1.1 92: */ 93: public abstract class MessageDigest extends MessageDigestSpi 94: { 95: /** The service name for message digests. */ 96: private static final String MESSAGE_DIGEST = "MessageDigest"; 97: 98: private String algorithm; 99: Provider provider; 100: private byte[] lastDigest; 101: 102: /** 103: * Creates a message digest with the specified algorithm name. 104: * 105: * @param algorithm the standard name of the digest algorithm. 106: * See Appendix A in the Java Cryptography Architecture API 107: * Specification & Reference for information about standard 108: * algorithm names. 109: */ 110: protected MessageDigest(String algorithm) 111: { 112: this.algorithm = algorithm; 113: provider = null; 114: } 115: 116: /** 117: * Generates a <code>MessageDigest</code> object that implements the specified 118: * digest algorithm. If the default provider package provides an 119: * implementation of the requested digest algorithm, an instance of 120: * <code>MessageDigest</code> containing that implementation is returned. If 121: * the algorithm is not available in the default package, other packages are 122: * searched. 123: * 124: * @param algorithm the name of the algorithm requested. See Appendix A in the 125: * Java Cryptography Architecture API Specification & Reference for 126: * information about standard algorithm names. 127: * @return a Message Digest object implementing the specified algorithm. 128: * @throws NoSuchAlgorithmException if the algorithm is not available in the 129: * caller's environment. 130: */ 131: public static MessageDigest getInstance(String algorithm) 132: throws NoSuchAlgorithmException 133: { 134: Provider[] p = Security.getProviders(); 135: for (int i = 0; i < p.length; i++) 136: { 137: try 138: { 139: return getInstance(algorithm, p[i]); 140: } 141: catch (NoSuchAlgorithmException ignored) 142: { 143: // Ignore. 144: } 145: } 146: 147: throw new NoSuchAlgorithmException(algorithm); 148: } 149: 150: /** 151: * Generates a <code>MessageDigest</code> object implementing the specified 152: * algorithm, as supplied from the specified provider, if such an algorithm is 153: * available from the provider. 154: * 155: * @param algorithm the name of the algorithm requested. See Appendix A in the 156: * Java Cryptography Architecture API Specification & Reference for 157: * information about standard algorithm names. 158: * @param provider the name of the provider. 159: * @return a Message Digest object implementing the specified algorithm. 160: * @throws NoSuchAlgorithmException if the algorithm is not available in the 161: * package supplied by the requested provider. 162: * @throws NoSuchProviderException if the provider is not available in the 163: * environment. 164: * @throws IllegalArgumentException if the provider name is null or empty. 165: * @see Provider 166: */ 167: public static MessageDigest getInstance(String algorithm, String provider) 168: throws NoSuchAlgorithmException, NoSuchProviderException 169: { 170: if (provider == null || provider.length() == 0) 171: throw new IllegalArgumentException("Illegal provider"); 172: 173: Provider p = Security.getProvider(provider); 174: if (p == null) 175: throw new NoSuchProviderException(provider); 176: 177: return getInstance(algorithm, p); 178: } 179: 180: /** 181: * Generates a <code>MessageDigest</code> object implementing the specified 182: * algorithm, as supplied from the specified provider, if such an algorithm 183: * is available from the provider. Note: the provider doesn't have to be 184: * registered. 185: * 186: * @param algorithm the name of the algorithm requested. See Appendix A in 187: * the Java Cryptography Architecture API Specification & Reference for 188: * information about standard algorithm names. 189: * @param provider the provider. 190: * @return a Message Digest object implementing the specified algorithm. 191: * @throws NoSuchAlgorithmException if the <code>algorithm</code> is not 192: * available in the package supplied by the requested <code>provider</code>. 193: * @throws IllegalArgumentException if the <code>provider</code> is 194: * <code>null</code>. 195: * @since 1.4 196: * @see Provider 197: */ 198: public static MessageDigest getInstance(String algorithm, Provider provider) 199: throws NoSuchAlgorithmException 200: { 201: if (provider == null) 202: throw new IllegalArgumentException("Illegal provider"); 203: 204: MessageDigest result = null; 205: Object o = null; 206: try 207: { 208: o = Engine.getInstance(MESSAGE_DIGEST, algorithm, provider); 209: } 210: catch (java.lang.reflect.InvocationTargetException ite) 211: { 212: throw new NoSuchAlgorithmException(algorithm); 213: } 214: 215: if (o instanceof MessageDigestSpi) 216: { 217: result = new DummyMessageDigest((MessageDigestSpi) o, algorithm); 218: } 219: else if (o instanceof MessageDigest) 220: { 221: result = (MessageDigest) o; 222: result.algorithm = algorithm; 223: } 224: else 225: { 226: throw new NoSuchAlgorithmException(algorithm); 227: } 228: result.provider = provider; 229: return result; 230: } 231: 232: /** 233: * Returns the provider of this message digest object. 234: * 235: * @return the provider of this message digest object. 236: */ 237: public final Provider getProvider() 238: { 239: return provider; 240: } 241: 242: /** 243: * Updates the digest using the specified byte. 244: * 245: * @param input the byte with which to update the digest. 246: */ 247: public void update(byte input) 248: { 249: engineUpdate(input); 250: } 251: 252: /** 253: * Updates the digest using the specified array of bytes, starting at the 254: * specified offset. 255: * 256: * @param input the array of bytes. 257: * @param offset the offset to start from in the array of bytes. 258: * @param len the number of bytes to use, starting at offset. 259: */ 260: public void update(byte[] input, int offset, int len) 261: { 262: engineUpdate(input, offset, len); 263: } 264: 265: /** 266: * Updates the digest using the specified array of bytes. 267: * 268: * @param input the array of bytes. 269: */ 270: public void update(byte[] input) 271: { 272: engineUpdate(input, 0, input.length); 273: } 274: 275: /** 276: * Completes the hash computation by performing final operations such as 277: * padding. The digest is reset after this call is made. 278: * 279: * @return the array of bytes for the resulting hash value. 280: */ 281: public byte[] digest() 282: { 283: return lastDigest = engineDigest(); 284: } 285: 286: /** 287: * Completes the hash computation by performing final operations such as 288: * padding. The digest is reset after this call is made. 289: * 290: * @param buf An output buffer for the computed digest. 291: * @param offset The offset into the output buffer to begin storing the digest. 292: * @param len The number of bytes within buf allotted for the digest. 293: * @return The number of bytes placed into buf. 294: * @throws DigestException if an error occurs. 295: */ 296: public int digest(byte[] buf, int offset, int len) throws DigestException 297: { 298: return engineDigest(buf, offset, len); 299: } 300: 301: /** 302: * Performs a final update on the digest using the specified array of bytes, 303: * then completes the digest computation. That is, this method first calls 304: * <code>update(input)</code>, passing the input array to the <code>update() 305: * </code> method, then calls <code>digest()</code>. 306: * 307: * @param input the input to be updated before the digest is completed. 308: * @return the array of bytes for the resulting hash value. 309: */ 310: public byte[] digest(byte[] input) 311: { 312: update(input); 313: return digest(); 314: } 315: 316: /** 317: * Returns a string representation of this message digest object. 318: * 319: * @return a string representation of the object. 320: */ 321: public String toString() 322: { 323: return (getClass()).getName() + " Message Digest <" + digestToString() + ">"; 324: } 325: 326: /** 327: * Compares two digests for equality. Does a simple byte compare. 328: * 329: * @param digesta one of the digests to compare. 330: * @param digestb the other digest to compare. 331: * @return <code>true</code> if the digests are equal, <code>false</code> 332: * otherwise. 333: */ 334: public static boolean isEqual(byte[] digesta, byte[] digestb) 335: { 336: if (digesta.length != digestb.length) 337: return false; 338: 339: for (int i = digesta.length - 1; i >= 0; --i) 340: if (digesta[i] != digestb[i]) 341: return false; 342: 343: return true; 344: } 345: 346: /** Resets the digest for further use. */ 347: public void reset() 348: { 349: engineReset(); 350: } 351: 352: /** 353: * Returns a string that identifies the algorithm, independent of 354: * implementation details. The name should be a standard Java Security name 355: * (such as <code>"SHA"</code>, <code>"MD5"</code>, and so on). See Appendix 356: * A in the Java Cryptography Architecture API Specification & Reference 357: * for information about standard algorithm names. 358: * 359: * @return the name of the algorithm. 360: */ 361: public final String getAlgorithm() 362: { 363: return algorithm; 364: } 365: 366: /** 367: * Returns the length of the digest in bytes, or <code>0</code> if this 368: * operation is not supported by the provider and the implementation is not 369: * cloneable. 370: * 371: * @return the digest length in bytes, or <code>0</code> if this operation is 372: * not supported by the provider and the implementation is not cloneable. 373: * @since 1.2 374: */ 375: public final int getDigestLength() 376: { 377: return engineGetDigestLength(); 378: } 379: 380: /** 381: * Returns a clone if the implementation is cloneable. 382: * 383: * @return a clone if the implementation is cloneable. 384: * @throws CloneNotSupportedException if this is called on an implementation 385: * that does not support {@link Cloneable}. 386: */ 387: public Object clone() throws CloneNotSupportedException 388: { 389: return super.clone(); 390: } 391: 392: private String digestToString() 393: { 394: byte[] digest = lastDigest; 395: 396: if (digest == null) 397: return "incomplete"; 398: 399: StringBuffer buf = new StringBuffer(); 400: int len = digest.length; 401: for (int i = 0; i < len; ++i) 402: { 403: byte b = digest[i]; 404: byte high = (byte) ((b & 0xff) >>> 4); 405: byte low = (byte) (b & 0xf); 406: 407: buf.append(high > 9 ? ('a' - 10) + high : '0' + high); 408: buf.append(low > 9 ? ('a' - 10) + low : '0' + low); 409: } 410: 411: return buf.toString(); 412: } 413: }
GNU Classpath (0.17) |