Source for gnu.javax.crypto.kwa.AESKeyWrap

   1: /* AESWrap.java -- An implementation of RFC-3394 AES Key Wrap Algorithm
   2:    Copyright (C) 2006 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: 
  39: package gnu.javax.crypto.kwa;
  40: 
  41: import gnu.java.security.Registry;
  42: import gnu.javax.crypto.cipher.IBlockCipher;
  43: import gnu.javax.crypto.cipher.Rijndael;
  44: 
  45: import java.security.InvalidKeyException;
  46: import java.util.Arrays;
  47: import java.util.HashMap;
  48: import java.util.Map;
  49: 
  50: /**
  51:  * The GNU implementation of the AES Key Wrap Algorithm as described in [1].
  52:  * <p>
  53:  * References:
  54:  * <ol>
  55:  * <li><a href="http://csrc.nist.gov/encryption/kms/key-wrap.pdf"></a>.</li>
  56:  * <li><a href="http://www.rfc-archive.org/getrfc.php?rfc=3394">Advanced
  57:  * Encryption Standard (AES) Key Wrap Algorithm</a>.</li>
  58:  * <li><a href="http://www.w3.org/TR/xmlenc-core/">XML Encryption Syntax and
  59:  * Processing</a>.</li>
  60:  * </ol>
  61:  */
  62: public class AESKeyWrap
  63:     extends BaseKeyWrappingAlgorithm
  64: {
  65:   private static final byte[] DEFAULT_IV = new byte[] {
  66:       (byte) 0xA6, (byte) 0xA6, (byte) 0xA6, (byte) 0xA6,
  67:       (byte) 0xA6, (byte) 0xA6, (byte) 0xA6, (byte) 0xA6 };
  68: 
  69:   private Rijndael aes;
  70:   private byte[] iv;
  71: 
  72:   public AESKeyWrap()
  73:   {
  74:     super(Registry.AES_KWA);
  75: 
  76:     aes = new Rijndael();
  77:   }
  78: 
  79:   protected void engineInit(Map attributes) throws InvalidKeyException
  80:   {
  81:     Map cipherAttributes = new HashMap();
  82:     cipherAttributes.put(IBlockCipher.CIPHER_BLOCK_SIZE, Integer.valueOf(16));
  83:     cipherAttributes.put(IBlockCipher.KEY_MATERIAL,
  84:                          attributes.get(KEY_ENCRYPTION_KEY_MATERIAL));
  85:     aes.reset();
  86:     aes.init(cipherAttributes);
  87:     byte[] initialValue = (byte[]) attributes.get(INITIAL_VALUE);
  88:     iv = initialValue == null ? DEFAULT_IV : (byte[]) initialValue.clone();
  89:   }
  90: 
  91:   protected byte[] engineWrap(byte[] in, int inOffset, int length)
  92:   {
  93:     // TODO: handle input length which is not a multiple of 8 as suggested by
  94:     // section 2.2.3.2 of RFC-3394
  95:     if (length % 8 != 0)
  96:       throw new IllegalArgumentException("Input length MUST be a multiple of 8");
  97:     int n = length / 8;
  98:     // output is always one block larger than input
  99:     byte[] result = new byte[length + 8];
 100: 
 101:     // 1. init variables: we'll use out buffer for our work buffer;
 102:     //    A will be the first block in out, while R will be the rest
 103:     System.arraycopy(iv, 0, result, 0, 8);
 104:     System.arraycopy(in, inOffset, result, 8, length);
 105:     byte[] B = new byte[2 * 8];
 106:     // 2. compute intermediate values
 107:     long t;
 108:     for (int j = 0; j < 6; j++)
 109:       for (int i = 1; i <= n; i++)
 110:         {
 111:           System.arraycopy(result, 0, B, 0, 8);
 112:           System.arraycopy(result, i * 8, B, 8, 8);
 113:           aes.encryptBlock(B, 0, B, 0);
 114:           t = (n * j) + i;
 115:           result[0] = (byte)(B[0] ^ (t >>> 56));
 116:           result[1] = (byte)(B[1] ^ (t >>> 48));
 117:           result[2] = (byte)(B[2] ^ (t >>> 40));
 118:           result[3] = (byte)(B[3] ^ (t >>> 32));
 119:           result[4] = (byte)(B[4] ^ (t >>> 24));
 120:           result[5] = (byte)(B[5] ^ (t >>> 16));
 121:           result[6] = (byte)(B[6] ^ (t >>>  8));
 122:           result[7] = (byte)(B[7] ^  t        );
 123:           System.arraycopy(B, 8, result, i * 8, 8);
 124:         }
 125:     return result;
 126:   }
 127: 
 128:   protected byte[] engineUnwrap(byte[] in, int inOffset, int length)
 129:       throws KeyUnwrappingException
 130:   {
 131:     // TODO: handle input length which is not a multiple of 8 as suggested by
 132:     // section 2.2.3.2 of RFC-3394
 133:     if (length % 8 != 0)
 134:       throw new IllegalArgumentException("Input length MUST be a multiple of 8");
 135:     // output is always one block shorter than input
 136:     byte[] result = new byte[length - 8];
 137: 
 138:     // 1. init variables: we'll use out buffer for our R work buffer
 139:     byte[] A = new byte[8];
 140:     System.arraycopy(in, inOffset, A, 0, 8);
 141:     System.arraycopy(in, inOffset + 8, result, 0, result.length);
 142:     byte[] B = new byte[2 * 8];
 143:     // 2. compute intermediate values
 144:     int n = length / 8 - 1;
 145:     long t;
 146:     for (int j = 5; j >= 0; j--)
 147:       for (int i = n; i >= 1; i--)
 148:         {
 149:           t = (n * j) + i;
 150:           B[0] = (byte)(A[0] ^ (t >>> 56));
 151:           B[1] = (byte)(A[1] ^ (t >>> 48));
 152:           B[2] = (byte)(A[2] ^ (t >>> 40));
 153:           B[3] = (byte)(A[3] ^ (t >>> 32));
 154:           B[4] = (byte)(A[4] ^ (t >>> 24));
 155:           B[5] = (byte)(A[5] ^ (t >>> 16));
 156:           B[6] = (byte)(A[6] ^ (t >>>  8));
 157:           B[7] = (byte)(A[7] ^  t        );
 158:           System.arraycopy(result, (i - 1) * 8, B, 8, 8);
 159:           aes.decryptBlock(B, 0, B, 0);
 160:           System.arraycopy(B, 0, A, 0, 8);
 161:           System.arraycopy(B, 8, result, (i - 1) * 8, 8);
 162:         }
 163:     if (! Arrays.equals(A, iv))
 164:       throw new KeyUnwrappingException();
 165: 
 166:     return result;
 167:   }
 168: }