J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2004-2007 Sun Microsystems, Inc. All Rights Reserved. |
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 | * |
| 5 | * This code is free software; you can redistribute it and/or modify it |
| 6 | * under the terms of the GNU General Public License version 2 only, as |
| 7 | * published by the Free Software Foundation. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun in the LICENSE file that accompanied this code. |
| 10 | * |
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT |
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 14 | * version 2 for more details (a copy is included in the LICENSE file that |
| 15 | * accompanied this code). |
| 16 | * |
| 17 | * You should have received a copy of the GNU General Public License version |
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, |
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| 20 | * |
| 21 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | |
| 26 | package com.sun.crypto.provider; |
| 27 | |
| 28 | import java.util.Arrays; |
| 29 | import java.security.*; |
| 30 | import java.security.spec.*; |
| 31 | import javax.crypto.*; |
| 32 | import javax.crypto.spec.*; |
| 33 | |
| 34 | /** |
| 35 | * This class implements the CMS DESede KeyWrap algorithm as defined |
| 36 | * in <a href=http://www.w3.org/TR/xmlenc-core/#sec-Alg-SymmetricKeyWrap> |
| 37 | * "XML Encryption Syntax and Processing" section 5.6.2 |
| 38 | * "CMS Triple DES Key Wrap". |
| 39 | * Note: only <code>CBC</code> mode and <code>NoPadding</code> padding |
| 40 | * scheme can be used for this algorithm. |
| 41 | * |
| 42 | * @author Valerie Peng |
| 43 | * |
| 44 | * |
| 45 | * @see DESedeCipher |
| 46 | */ |
| 47 | public final class DESedeWrapCipher extends CipherSpi { |
| 48 | |
| 49 | private static final byte[] IV2 = { |
| 50 | (byte) 0x4a, (byte) 0xdd, (byte) 0xa2, (byte) 0x2c, |
| 51 | (byte) 0x79, (byte) 0xe8, (byte) 0x21, (byte) 0x05 |
| 52 | }; |
| 53 | |
| 54 | /* |
| 55 | * internal cipher object which does the real work. |
| 56 | */ |
| 57 | private FeedbackCipher cipher; |
| 58 | |
| 59 | /* |
| 60 | * iv for (re-)initializing the internal cipher object. |
| 61 | */ |
| 62 | private byte[] iv = null; |
| 63 | |
| 64 | /* |
| 65 | * key for re-initializing the internal cipher object. |
| 66 | */ |
| 67 | private Key cipherKey = null; |
| 68 | |
| 69 | /* |
| 70 | * are we encrypting or decrypting? |
| 71 | */ |
| 72 | private boolean decrypting = false; |
| 73 | |
| 74 | /** |
| 75 | * Creates an instance of CMS DESede KeyWrap cipher with default |
| 76 | * mode, i.e. "CBC" and padding scheme, i.e. "NoPadding". |
| 77 | * |
| 78 | * @exception SecurityException if this constructor fails to verify |
| 79 | * its own integrity. |
| 80 | */ |
| 81 | public DESedeWrapCipher() { |
| 82 | SunJCE.ensureIntegrity(getClass()); |
| 83 | cipher = new CipherBlockChaining(new DESedeCrypt()); |
| 84 | } |
| 85 | |
| 86 | /** |
| 87 | * Sets the mode of this cipher. Only "CBC" mode is accepted for this |
| 88 | * cipher. |
| 89 | * |
| 90 | * @param mode the cipher mode. |
| 91 | * |
| 92 | * @exception NoSuchAlgorithmException if the requested cipher mode |
| 93 | * is not "CBC". |
| 94 | */ |
| 95 | protected void engineSetMode(String mode) |
| 96 | throws NoSuchAlgorithmException { |
| 97 | if (!mode.equalsIgnoreCase("CBC")) { |
| 98 | throw new NoSuchAlgorithmException(mode + " cannot be used"); |
| 99 | } |
| 100 | } |
| 101 | |
| 102 | /** |
| 103 | * Sets the padding mechanism of this cipher. Only "NoPadding" schmem |
| 104 | * is accepted for this cipher. |
| 105 | * |
| 106 | * @param padding the padding mechanism. |
| 107 | * |
| 108 | * @exception NoSuchPaddingException if the requested padding mechanism |
| 109 | * is not "NoPadding". |
| 110 | */ |
| 111 | protected void engineSetPadding(String padding) |
| 112 | throws NoSuchPaddingException { |
| 113 | if (!padding.equalsIgnoreCase("NoPadding")) { |
| 114 | throw new NoSuchPaddingException(padding + " cannot be used"); |
| 115 | } |
| 116 | } |
| 117 | |
| 118 | /** |
| 119 | * Returns the block size (in bytes), i.e. 8 bytes. |
| 120 | * |
| 121 | * @return the block size (in bytes), i.e. 8 bytes. |
| 122 | */ |
| 123 | protected int engineGetBlockSize() { |
| 124 | return DESConstants.DES_BLOCK_SIZE; |
| 125 | } |
| 126 | |
| 127 | /** |
| 128 | * Returns the length in bytes that an output buffer would need to be |
| 129 | * given the input length <code>inputLen</code> (in bytes). |
| 130 | * |
| 131 | * <p>The actual output length of the next <code>update</code> or |
| 132 | * <code>doFinal</code> call may be smaller than the length returned |
| 133 | * by this method. |
| 134 | * |
| 135 | * @param inputLen the input length (in bytes). |
| 136 | * |
| 137 | * @return the required output buffer size (in bytes). |
| 138 | */ |
| 139 | protected int engineGetOutputSize(int inputLen) { |
| 140 | // can only return an upper-limit if not initialized yet. |
| 141 | int result = 0; |
| 142 | if (decrypting) { |
| 143 | result = inputLen - 16; |
| 144 | } else { |
| 145 | result = inputLen + 16; |
| 146 | } |
| 147 | return (result < 0? 0:result); |
| 148 | } |
| 149 | |
| 150 | /** |
| 151 | * Returns the initialization vector (IV) in a new buffer. |
| 152 | * |
| 153 | * @return the initialization vector, or null if the underlying |
| 154 | * algorithm does not use an IV, or if the IV has not yet |
| 155 | * been set. |
| 156 | */ |
| 157 | protected byte[] engineGetIV() { |
| 158 | return (iv == null? null:(byte[]) iv.clone()); |
| 159 | } |
| 160 | |
| 161 | /** |
| 162 | * Initializes this cipher with a key and a source of randomness. |
| 163 | * |
| 164 | * <p>The cipher only supports the following two operation modes:<b> |
| 165 | * Cipher.WRAP_MODE, and <b> |
| 166 | * Cipher.UNWRAP_MODE. |
| 167 | * <p>For modes other than the above two, UnsupportedOperationException |
| 168 | * will be thrown. |
| 169 | * <p>If this cipher requires an initialization vector (IV), it will get |
| 170 | * it from <code>random</code>. |
| 171 | * |
| 172 | * @param opmode the operation mode of this cipher. Only |
| 173 | * <code>WRAP_MODE</code> or <code>UNWRAP_MODE</code>) are accepted. |
| 174 | * @param key the secret key. |
| 175 | * @param random the source of randomness. |
| 176 | * |
| 177 | * @exception InvalidKeyException if the given key is inappropriate |
| 178 | * or if parameters are required but not supplied. |
| 179 | */ |
| 180 | protected void engineInit(int opmode, Key key, SecureRandom random) |
| 181 | throws InvalidKeyException { |
| 182 | try { |
| 183 | engineInit(opmode, key, (AlgorithmParameterSpec) null, random); |
| 184 | } catch (InvalidAlgorithmParameterException iape) { |
| 185 | // should never happen |
| 186 | InvalidKeyException ike = |
| 187 | new InvalidKeyException("Parameters required"); |
| 188 | ike.initCause(iape); |
| 189 | throw ike; |
| 190 | } |
| 191 | } |
| 192 | |
| 193 | /** |
| 194 | * Initializes this cipher with a key, a set of algorithm parameters, |
| 195 | * and a source of randomness. |
| 196 | * |
| 197 | * <p>The cipher only supports the following two operation modes:<b> |
| 198 | * Cipher.WRAP_MODE, and <b> |
| 199 | * Cipher.UNWRAP_MODE. |
| 200 | * <p>For modes other than the above two, UnsupportedOperationException |
| 201 | * will be thrown. |
| 202 | * <p>If this cipher requires an initialization vector (IV), it will get |
| 203 | * it from <code>random</code>. |
| 204 | * |
| 205 | * @param opmode the operation mode of this cipher. Only |
| 206 | * <code>WRAP_MODE</code> or <code>UNWRAP_MODE</code>) are accepted. |
| 207 | * @param key the secret key. |
| 208 | * @param params the algorithm parameters. |
| 209 | * @param random the source of randomness. |
| 210 | * |
| 211 | * @exception InvalidKeyException if the given key is inappropriate. |
| 212 | * @exception InvalidAlgorithmParameterException if the given algorithm |
| 213 | * parameters are inappropriate for this cipher. |
| 214 | */ |
| 215 | protected void engineInit(int opmode, Key key, |
| 216 | AlgorithmParameterSpec params, |
| 217 | SecureRandom random) |
| 218 | throws InvalidKeyException, InvalidAlgorithmParameterException { |
| 219 | byte[] currIv = null; |
| 220 | if (opmode == Cipher.WRAP_MODE) { |
| 221 | decrypting = false; |
| 222 | if (params == null) { |
| 223 | iv = new byte[8]; |
| 224 | if (random == null) { |
| 225 | random = SunJCE.RANDOM; |
| 226 | } |
| 227 | random.nextBytes(iv); |
| 228 | } |
| 229 | else if (params instanceof IvParameterSpec) { |
| 230 | iv = ((IvParameterSpec) params).getIV(); |
| 231 | } else { |
| 232 | throw new InvalidAlgorithmParameterException |
| 233 | ("Wrong parameter type: IV expected"); |
| 234 | } |
| 235 | currIv = iv; |
| 236 | } else if (opmode == Cipher.UNWRAP_MODE) { |
| 237 | if (params != null) { |
| 238 | throw new InvalidAlgorithmParameterException |
| 239 | ("No parameter accepted for unwrapping keys"); |
| 240 | } |
| 241 | iv = null; |
| 242 | decrypting = true; |
| 243 | currIv = IV2; |
| 244 | } else { |
| 245 | throw new UnsupportedOperationException("This cipher can " + |
| 246 | "only be used for key wrapping and unwrapping"); |
| 247 | } |
| 248 | cipher.init(decrypting, key.getAlgorithm(), key.getEncoded(), |
| 249 | currIv); |
| 250 | cipherKey = key; |
| 251 | } |
| 252 | |
| 253 | /** |
| 254 | * Initializes this cipher with a key, a set of algorithm parameters, |
| 255 | * and a source of randomness. |
| 256 | * |
| 257 | * <p>The cipher only supports the following two operation modes:<b> |
| 258 | * Cipher.WRAP_MODE, and <b> |
| 259 | * Cipher.UNWRAP_MODE. |
| 260 | * <p>For modes other than the above two, UnsupportedOperationException |
| 261 | * will be thrown. |
| 262 | * <p>If this cipher requires an initialization vector (IV), it will get |
| 263 | * it from <code>random</code>. |
| 264 | * |
| 265 | * @param opmode the operation mode of this cipher. Only |
| 266 | * <code>WRAP_MODE</code> or <code>UNWRAP_MODE</code>) are accepted. |
| 267 | * @param key the secret key. |
| 268 | * @param params the algorithm parameters. |
| 269 | * @param random the source of randomness. |
| 270 | * |
| 271 | * @exception InvalidKeyException if the given key is inappropriate. |
| 272 | * @exception InvalidAlgorithmParameterException if the given algorithm |
| 273 | * parameters are inappropriate for this cipher. |
| 274 | */ |
| 275 | protected void engineInit(int opmode, Key key, |
| 276 | AlgorithmParameters params, |
| 277 | SecureRandom random) |
| 278 | throws InvalidKeyException, InvalidAlgorithmParameterException { |
| 279 | IvParameterSpec ivSpec = null; |
| 280 | if (params != null) { |
| 281 | try { |
| 282 | DESedeParameters paramsEng = new DESedeParameters(); |
| 283 | paramsEng.engineInit(params.getEncoded()); |
| 284 | ivSpec = (IvParameterSpec) |
| 285 | paramsEng.engineGetParameterSpec(IvParameterSpec.class); |
| 286 | } catch (Exception ex) { |
| 287 | InvalidAlgorithmParameterException iape = |
| 288 | new InvalidAlgorithmParameterException |
| 289 | ("Wrong parameter type: IV expected"); |
| 290 | iape.initCause(ex); |
| 291 | throw iape; |
| 292 | } |
| 293 | } |
| 294 | engineInit(opmode, key, ivSpec, random); |
| 295 | } |
| 296 | |
| 297 | /** |
| 298 | * This operation is not supported by this cipher. |
| 299 | * Since it's impossible to initialize this cipher given the |
| 300 | * current Cipher.engineInit(...) implementation, |
| 301 | * IllegalStateException will always be thrown upon invocation. |
| 302 | * |
| 303 | * @param in the input buffer. |
| 304 | * @param inOffset the offset in <code>in</code> where the input |
| 305 | * starts. |
| 306 | * @param inLen the input length. |
| 307 | * |
| 308 | * @return n/a. |
| 309 | * |
| 310 | * @exception IllegalStateException upon invocation of this method. |
| 311 | */ |
| 312 | protected byte[] engineUpdate(byte[] in, int inOffset, int inLen) { |
| 313 | throw new IllegalStateException("Cipher has not been initialized"); |
| 314 | } |
| 315 | |
| 316 | /** |
| 317 | * This operation is not supported by this cipher. |
| 318 | * Since it's impossible to initialize this cipher given the |
| 319 | * current Cipher.engineInit(...) implementation, |
| 320 | * IllegalStateException will always be thrown upon invocation. |
| 321 | * |
| 322 | * @param in the input buffer. |
| 323 | * @param inOffset the offset in <code>in</code> where the input |
| 324 | * starts. |
| 325 | * @param inLen the input length. |
| 326 | * @param out the buffer for the result. |
| 327 | * @param outOffset the offset in <code>out</code> where the result |
| 328 | * is stored. |
| 329 | * |
| 330 | * @return n/a. |
| 331 | * |
| 332 | * @exception IllegalStateException upon invocation of this method. |
| 333 | */ |
| 334 | protected int engineUpdate(byte[] in, int inOffset, int inLen, |
| 335 | byte[] out, int outOffset) |
| 336 | throws ShortBufferException { |
| 337 | throw new IllegalStateException("Cipher has not been initialized"); |
| 338 | } |
| 339 | |
| 340 | /** |
| 341 | * This operation is not supported by this cipher. |
| 342 | * Since it's impossible to initialize this cipher given the |
| 343 | * current Cipher.engineInit(...) implementation, |
| 344 | * IllegalStateException will always be thrown upon invocation. |
| 345 | * |
| 346 | * @param in the input buffer. |
| 347 | * @param inOffset the offset in <code>in</code> where the input |
| 348 | * starts. |
| 349 | * @param inLen the input length. |
| 350 | * |
| 351 | * @return the new buffer with the result. |
| 352 | * |
| 353 | * @exception IllegalStateException upon invocation of this method. |
| 354 | */ |
| 355 | protected byte[] engineDoFinal(byte[] in, int inOffset, int inLen) |
| 356 | throws IllegalBlockSizeException, BadPaddingException { |
| 357 | throw new IllegalStateException("Cipher has not been initialized"); |
| 358 | } |
| 359 | |
| 360 | /** |
| 361 | * This operation is not supported by this cipher. |
| 362 | * Since it's impossible to initialize this cipher given the |
| 363 | * current Cipher.engineInit(...) implementation, |
| 364 | * IllegalStateException will always be thrown upon invocation. |
| 365 | * |
| 366 | * @param in the input buffer. |
| 367 | * @param inOffset the offset in <code>in</code> where the input |
| 368 | * starts. |
| 369 | * @param inLen the input length. |
| 370 | * @param out the buffer for the result. |
| 371 | * @param outOffset the ofset in <code>out</code> where the result |
| 372 | * is stored. |
| 373 | * |
| 374 | * @return the number of bytes stored in <code>out</code>. |
| 375 | * |
| 376 | * @exception IllegalStateException upon invocation of this method. |
| 377 | */ |
| 378 | protected int engineDoFinal(byte[] input, int inputOffset, int inputLen, |
| 379 | byte[] output, int outputOffset) |
| 380 | throws IllegalBlockSizeException, ShortBufferException, |
| 381 | BadPaddingException { |
| 382 | throw new IllegalStateException("Cipher has not been initialized"); |
| 383 | } |
| 384 | |
| 385 | /** |
| 386 | * Returns the parameters used with this cipher. |
| 387 | * Note that null maybe returned if this cipher does not use any |
| 388 | * parameters or when it has not be set, e.g. initialized with |
| 389 | * UNWRAP_MODE but wrapped key data has not been given. |
| 390 | * |
| 391 | * @return the parameters used with this cipher; can be null. |
| 392 | */ |
| 393 | protected AlgorithmParameters engineGetParameters() { |
| 394 | AlgorithmParameters params = null; |
| 395 | if (iv != null) { |
| 396 | String algo = cipherKey.getAlgorithm(); |
| 397 | try { |
| 398 | params = AlgorithmParameters.getInstance(algo, "SunJCE"); |
| 399 | } catch (NoSuchAlgorithmException nsae) { |
| 400 | // should never happen |
| 401 | throw new RuntimeException("Cannot find " + algo + |
| 402 | " AlgorithmParameters implementation in SunJCE provider"); |
| 403 | } catch (NoSuchProviderException nspe) { |
| 404 | // should never happen |
| 405 | throw new RuntimeException("Cannot find SunJCE provider"); |
| 406 | } |
| 407 | try { |
| 408 | params.init(new IvParameterSpec(iv)); |
| 409 | } catch (InvalidParameterSpecException ipse) { |
| 410 | // should never happen |
| 411 | throw new RuntimeException("IvParameterSpec not supported"); |
| 412 | } |
| 413 | } |
| 414 | return params; |
| 415 | } |
| 416 | |
| 417 | /** |
| 418 | * Returns the key size of the given key object in number of bits. |
| 419 | * This cipher always return the same key size as the DESede ciphers. |
| 420 | * |
| 421 | * @param key the key object. |
| 422 | * |
| 423 | * @return the "effective" key size of the given key object. |
| 424 | * |
| 425 | * @exception InvalidKeyException if <code>key</code> is invalid. |
| 426 | */ |
| 427 | protected int engineGetKeySize(Key key) throws InvalidKeyException { |
| 428 | byte[] encoded = key.getEncoded(); |
| 429 | if (encoded.length != 24) { |
| 430 | throw new InvalidKeyException("Invalid key length: " + |
| 431 | encoded.length + " bytes"); |
| 432 | } |
| 433 | // Return the effective key length |
| 434 | return 112; |
| 435 | } |
| 436 | |
| 437 | /** |
| 438 | * Wrap a key. |
| 439 | * |
| 440 | * @param key the key to be wrapped. |
| 441 | * |
| 442 | * @return the wrapped key. |
| 443 | * |
| 444 | * @exception IllegalBlockSizeException if this cipher is a block |
| 445 | * cipher, no padding has been requested, and the length of the |
| 446 | * encoding of the key to be wrapped is not a |
| 447 | * multiple of the block size. |
| 448 | * |
| 449 | * @exception InvalidKeyException if it is impossible or unsafe to |
| 450 | * wrap the key with this cipher (e.g., a hardware protected key is |
| 451 | * being passed to a software only cipher). |
| 452 | */ |
| 453 | protected byte[] engineWrap(Key key) |
| 454 | throws IllegalBlockSizeException, InvalidKeyException { |
| 455 | byte[] keyVal = key.getEncoded(); |
| 456 | if ((keyVal == null) || (keyVal.length == 0)) { |
| 457 | throw new InvalidKeyException("Cannot get an encoding of " + |
| 458 | "the key to be wrapped"); |
| 459 | } |
| 460 | |
| 461 | byte[] cks = getChecksum(keyVal); |
| 462 | byte[] out = new byte[iv.length + keyVal.length + cks.length]; |
| 463 | |
| 464 | System.arraycopy(keyVal, 0, out, iv.length, keyVal.length); |
| 465 | System.arraycopy(cks, 0, out, iv.length+keyVal.length, cks.length); |
| 466 | cipher.encrypt(out, iv.length, keyVal.length+cks.length, |
| 467 | out, iv.length); |
| 468 | |
| 469 | System.arraycopy(iv, 0, out, 0, iv.length); |
| 470 | // reverse the array content |
| 471 | for (int i = 0; i < out.length/2; i++) { |
| 472 | byte temp = out[i]; |
| 473 | out[i] = out[out.length-1-i]; |
| 474 | out[out.length-1-i] = temp; |
| 475 | } |
| 476 | try { |
| 477 | cipher.init(false, cipherKey.getAlgorithm(), |
| 478 | cipherKey.getEncoded(), IV2); |
| 479 | } catch (InvalidKeyException ike) { |
| 480 | // should never happen |
| 481 | throw new RuntimeException("Internal cipher key is corrupted"); |
| 482 | } |
| 483 | cipher.encrypt(out, 0, out.length, out, 0); |
| 484 | |
| 485 | // restore cipher state to prior to this call |
| 486 | try { |
| 487 | cipher.init(decrypting, cipherKey.getAlgorithm(), |
| 488 | cipherKey.getEncoded(), iv); |
| 489 | } catch (InvalidKeyException ike) { |
| 490 | // should never happen |
| 491 | throw new RuntimeException("Internal cipher key is corrupted"); |
| 492 | } |
| 493 | return out; |
| 494 | } |
| 495 | |
| 496 | /** |
| 497 | * Unwrap a previously wrapped key. |
| 498 | * |
| 499 | * @param wrappedKey the key to be unwrapped. |
| 500 | * |
| 501 | * @param wrappedKeyAlgorithm the algorithm the wrapped key is for. |
| 502 | * |
| 503 | * @param wrappedKeyType the type of the wrapped key. |
| 504 | * This is one of <code>Cipher.SECRET_KEY</code>, |
| 505 | * <code>Cipher.PRIVATE_KEY</code>, or <code>Cipher.PUBLIC_KEY</code>. |
| 506 | * |
| 507 | * @return the unwrapped key. |
| 508 | * |
| 509 | * @exception NoSuchAlgorithmException if no installed providers |
| 510 | * can create keys of type <code>wrappedKeyType</code> for the |
| 511 | * <code>wrappedKeyAlgorithm</code>. |
| 512 | * |
| 513 | * @exception InvalidKeyException if <code>wrappedKey</code> does not |
| 514 | * represent a wrapped key of type <code>wrappedKeyType</code> for |
| 515 | * the <code>wrappedKeyAlgorithm</code>. |
| 516 | */ |
| 517 | protected Key engineUnwrap(byte[] wrappedKey, |
| 518 | String wrappedKeyAlgorithm, |
| 519 | int wrappedKeyType) |
| 520 | throws InvalidKeyException, NoSuchAlgorithmException { |
| 521 | if (wrappedKey.length == 0) { |
| 522 | throw new InvalidKeyException("The wrapped key is empty"); |
| 523 | } |
| 524 | byte[] buffer = new byte[wrappedKey.length]; |
| 525 | cipher.decrypt(wrappedKey, 0, wrappedKey.length, buffer, 0); |
| 526 | |
| 527 | // reverse array content |
| 528 | for (int i = 0; i < buffer.length/2; i++) { |
| 529 | byte temp = buffer[i]; |
| 530 | buffer[i] = buffer[buffer.length-1-i]; |
| 531 | buffer[buffer.length-1-i] = temp; |
| 532 | } |
| 533 | iv = new byte[IV2.length]; |
| 534 | System.arraycopy(buffer, 0, iv, 0, iv.length); |
| 535 | cipher.init(true, cipherKey.getAlgorithm(), cipherKey.getEncoded(), |
| 536 | iv); |
| 537 | cipher.decrypt(buffer, iv.length, buffer.length-iv.length, |
| 538 | buffer, iv.length); |
| 539 | int origLen = buffer.length - iv.length - 8; |
| 540 | byte[] cks = getChecksum(buffer, iv.length, origLen); |
| 541 | int offset = iv.length + origLen; |
| 542 | for (int i = 0; i < cks.length; i++) { |
| 543 | if (buffer[offset + i] != cks[i]) { |
| 544 | throw new InvalidKeyException("Checksum comparison failed"); |
| 545 | } |
| 546 | } |
| 547 | // restore cipher state to prior to this call |
| 548 | cipher.init(decrypting, cipherKey.getAlgorithm(), |
| 549 | cipherKey.getEncoded(), IV2); |
| 550 | byte[] out = new byte[origLen]; |
| 551 | System.arraycopy(buffer, iv.length, out, 0, out.length); |
| 552 | return ConstructKeys.constructKey(out, wrappedKeyAlgorithm, |
| 553 | wrappedKeyType); |
| 554 | } |
| 555 | |
| 556 | private static final byte[] getChecksum(byte[] in) { |
| 557 | return getChecksum(in, 0, in.length); |
| 558 | } |
| 559 | private static final byte[] getChecksum(byte[] in, int offset, int len) { |
| 560 | MessageDigest md = null; |
| 561 | try { |
| 562 | md = MessageDigest.getInstance("SHA1"); |
| 563 | } catch (NoSuchAlgorithmException nsae) { |
| 564 | throw new RuntimeException("SHA1 message digest not available"); |
| 565 | } |
| 566 | md.update(in, offset, len); |
| 567 | byte[] cks = new byte[8]; |
| 568 | System.arraycopy(md.digest(), 0, cks, 0, cks.length); |
| 569 | return cks; |
| 570 | } |
| 571 | } |