Shuyi Chen | d7955ce | 2013-05-22 14:51:55 -0700 | [diff] [blame] | 1 | // Copyright (c) 1999-2004 Brian Wellington (bwelling@xbill.org) |
| 2 | |
| 3 | package org.xbill.DNS.utils; |
| 4 | |
| 5 | import java.util.Arrays; |
| 6 | import java.security.*; |
| 7 | |
| 8 | /** |
| 9 | * An implementation of the HMAC message authentication code. |
| 10 | * |
| 11 | * @author Brian Wellington |
| 12 | */ |
| 13 | |
| 14 | public class HMAC { |
| 15 | |
| 16 | private MessageDigest digest; |
| 17 | private int blockLength; |
| 18 | |
| 19 | private byte [] ipad, opad; |
| 20 | |
| 21 | private static final byte IPAD = 0x36; |
| 22 | private static final byte OPAD = 0x5c; |
| 23 | |
| 24 | private void |
| 25 | init(byte [] key) { |
| 26 | int i; |
| 27 | |
| 28 | if (key.length > blockLength) { |
| 29 | key = digest.digest(key); |
| 30 | digest.reset(); |
| 31 | } |
| 32 | ipad = new byte[blockLength]; |
| 33 | opad = new byte[blockLength]; |
| 34 | for (i = 0; i < key.length; i++) { |
| 35 | ipad[i] = (byte) (key[i] ^ IPAD); |
| 36 | opad[i] = (byte) (key[i] ^ OPAD); |
| 37 | } |
| 38 | for (; i < blockLength; i++) { |
| 39 | ipad[i] = IPAD; |
| 40 | opad[i] = OPAD; |
| 41 | } |
| 42 | digest.update(ipad); |
| 43 | } |
| 44 | |
| 45 | /** |
| 46 | * Creates a new HMAC instance |
| 47 | * @param digest The message digest object. |
| 48 | * @param blockLength The block length of the message digest. |
| 49 | * @param key The secret key |
| 50 | */ |
| 51 | public |
| 52 | HMAC(MessageDigest digest, int blockLength, byte [] key) { |
| 53 | digest.reset(); |
| 54 | this.digest = digest; |
| 55 | this.blockLength = blockLength; |
| 56 | init(key); |
| 57 | } |
| 58 | |
| 59 | /** |
| 60 | * Creates a new HMAC instance |
| 61 | * @param digestName The name of the message digest function. |
| 62 | * @param blockLength The block length of the message digest. |
| 63 | * @param key The secret key. |
| 64 | */ |
| 65 | public |
| 66 | HMAC(String digestName, int blockLength, byte [] key) { |
| 67 | try { |
| 68 | digest = MessageDigest.getInstance(digestName); |
| 69 | } catch (NoSuchAlgorithmException e) { |
| 70 | throw new IllegalArgumentException("unknown digest algorithm " |
| 71 | + digestName); |
| 72 | } |
| 73 | this.blockLength = blockLength; |
| 74 | init(key); |
| 75 | } |
| 76 | |
| 77 | /** |
| 78 | * Creates a new HMAC instance |
| 79 | * @param digest The message digest object. |
| 80 | * @param key The secret key |
| 81 | * @deprecated won't work with digests using a padding length other than 64; |
| 82 | * use {@code HMAC(MessageDigest digest, int blockLength, |
| 83 | * byte [] key)} instead. |
| 84 | * @see HMAC#HMAC(MessageDigest digest, int blockLength, byte [] key) |
| 85 | */ |
| 86 | public |
| 87 | HMAC(MessageDigest digest, byte [] key) { |
| 88 | this(digest, 64, key); |
| 89 | } |
| 90 | |
| 91 | /** |
| 92 | * Creates a new HMAC instance |
| 93 | * @param digestName The name of the message digest function. |
| 94 | * @param key The secret key. |
| 95 | * @deprecated won't work with digests using a padding length other than 64; |
| 96 | * use {@code HMAC(String digestName, int blockLength, byte [] key)} |
| 97 | * instead |
| 98 | * @see HMAC#HMAC(String digestName, int blockLength, byte [] key) |
| 99 | */ |
| 100 | public |
| 101 | HMAC(String digestName, byte [] key) { |
| 102 | this(digestName, 64, key); |
| 103 | } |
| 104 | |
| 105 | /** |
| 106 | * Adds data to the current hash |
| 107 | * @param b The data |
| 108 | * @param offset The index at which to start adding to the hash |
| 109 | * @param length The number of bytes to hash |
| 110 | */ |
| 111 | public void |
| 112 | update(byte [] b, int offset, int length) { |
| 113 | digest.update(b, offset, length); |
| 114 | } |
| 115 | |
| 116 | /** |
| 117 | * Adds data to the current hash |
| 118 | * @param b The data |
| 119 | */ |
| 120 | public void |
| 121 | update(byte [] b) { |
| 122 | digest.update(b); |
| 123 | } |
| 124 | |
| 125 | /** |
| 126 | * Signs the data (computes the secure hash) |
| 127 | * @return An array with the signature |
| 128 | */ |
| 129 | public byte [] |
| 130 | sign() { |
| 131 | byte [] output = digest.digest(); |
| 132 | digest.reset(); |
| 133 | digest.update(opad); |
| 134 | return digest.digest(output); |
| 135 | } |
| 136 | |
| 137 | /** |
| 138 | * Verifies the data (computes the secure hash and compares it to the input) |
| 139 | * @param signature The signature to compare against |
| 140 | * @return true if the signature matches, false otherwise |
| 141 | */ |
| 142 | public boolean |
| 143 | verify(byte [] signature) { |
| 144 | return verify(signature, false); |
| 145 | } |
| 146 | |
| 147 | /** |
| 148 | * Verifies the data (computes the secure hash and compares it to the input) |
| 149 | * @param signature The signature to compare against |
| 150 | * @param truncation_ok If true, the signature may be truncated; only the |
| 151 | * number of bytes in the provided signature are compared. |
| 152 | * @return true if the signature matches, false otherwise |
| 153 | */ |
| 154 | public boolean |
| 155 | verify(byte [] signature, boolean truncation_ok) { |
| 156 | byte [] expected = sign(); |
| 157 | if (truncation_ok && signature.length < expected.length) { |
| 158 | byte [] truncated = new byte[signature.length]; |
| 159 | System.arraycopy(expected, 0, truncated, 0, truncated.length); |
| 160 | expected = truncated; |
| 161 | } |
| 162 | return Arrays.equals(signature, expected); |
| 163 | } |
| 164 | |
| 165 | /** |
| 166 | * Resets the HMAC object for further use |
| 167 | */ |
| 168 | public void |
| 169 | clear() { |
| 170 | digest.reset(); |
| 171 | digest.update(ipad); |
| 172 | } |
| 173 | |
| 174 | /** |
| 175 | * Returns the length of the digest. |
| 176 | */ |
| 177 | public int |
| 178 | digestLength() { |
| 179 | return digest.getDigestLength(); |
| 180 | } |
| 181 | |
| 182 | } |