J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2000-2005 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 java.util.prefs; |
| 27 | |
| 28 | /** |
| 29 | * Static methods for translating Base64 encoded strings to byte arrays |
| 30 | * and vice-versa. |
| 31 | * |
| 32 | * @author Josh Bloch |
| 33 | * @see Preferences |
| 34 | * @since 1.4 |
| 35 | */ |
| 36 | class Base64 { |
| 37 | /** |
| 38 | * Translates the specified byte array into a Base64 string as per |
| 39 | * Preferences.put(byte[]). |
| 40 | */ |
| 41 | static String byteArrayToBase64(byte[] a) { |
| 42 | return byteArrayToBase64(a, false); |
| 43 | } |
| 44 | |
| 45 | /** |
| 46 | * Translates the specified byte array into an "alternate representation" |
| 47 | * Base64 string. This non-standard variant uses an alphabet that does |
| 48 | * not contain the uppercase alphabetic characters, which makes it |
| 49 | * suitable for use in situations where case-folding occurs. |
| 50 | */ |
| 51 | static String byteArrayToAltBase64(byte[] a) { |
| 52 | return byteArrayToBase64(a, true); |
| 53 | } |
| 54 | |
| 55 | private static String byteArrayToBase64(byte[] a, boolean alternate) { |
| 56 | int aLen = a.length; |
| 57 | int numFullGroups = aLen/3; |
| 58 | int numBytesInPartialGroup = aLen - 3*numFullGroups; |
| 59 | int resultLen = 4*((aLen + 2)/3); |
| 60 | StringBuffer result = new StringBuffer(resultLen); |
| 61 | char[] intToAlpha = (alternate ? intToAltBase64 : intToBase64); |
| 62 | |
| 63 | // Translate all full groups from byte array elements to Base64 |
| 64 | int inCursor = 0; |
| 65 | for (int i=0; i<numFullGroups; i++) { |
| 66 | int byte0 = a[inCursor++] & 0xff; |
| 67 | int byte1 = a[inCursor++] & 0xff; |
| 68 | int byte2 = a[inCursor++] & 0xff; |
| 69 | result.append(intToAlpha[byte0 >> 2]); |
| 70 | result.append(intToAlpha[(byte0 << 4)&0x3f | (byte1 >> 4)]); |
| 71 | result.append(intToAlpha[(byte1 << 2)&0x3f | (byte2 >> 6)]); |
| 72 | result.append(intToAlpha[byte2 & 0x3f]); |
| 73 | } |
| 74 | |
| 75 | // Translate partial group if present |
| 76 | if (numBytesInPartialGroup != 0) { |
| 77 | int byte0 = a[inCursor++] & 0xff; |
| 78 | result.append(intToAlpha[byte0 >> 2]); |
| 79 | if (numBytesInPartialGroup == 1) { |
| 80 | result.append(intToAlpha[(byte0 << 4) & 0x3f]); |
| 81 | result.append("=="); |
| 82 | } else { |
| 83 | // assert numBytesInPartialGroup == 2; |
| 84 | int byte1 = a[inCursor++] & 0xff; |
| 85 | result.append(intToAlpha[(byte0 << 4)&0x3f | (byte1 >> 4)]); |
| 86 | result.append(intToAlpha[(byte1 << 2)&0x3f]); |
| 87 | result.append('='); |
| 88 | } |
| 89 | } |
| 90 | // assert inCursor == a.length; |
| 91 | // assert result.length() == resultLen; |
| 92 | return result.toString(); |
| 93 | } |
| 94 | |
| 95 | /** |
| 96 | * This array is a lookup table that translates 6-bit positive integer |
| 97 | * index values into their "Base64 Alphabet" equivalents as specified |
| 98 | * in Table 1 of RFC 2045. |
| 99 | */ |
| 100 | private static final char intToBase64[] = { |
| 101 | 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', |
| 102 | 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', |
| 103 | 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', |
| 104 | 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', |
| 105 | '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/' |
| 106 | }; |
| 107 | |
| 108 | /** |
| 109 | * This array is a lookup table that translates 6-bit positive integer |
| 110 | * index values into their "Alternate Base64 Alphabet" equivalents. |
| 111 | * This is NOT the real Base64 Alphabet as per in Table 1 of RFC 2045. |
| 112 | * This alternate alphabet does not use the capital letters. It is |
| 113 | * designed for use in environments where "case folding" occurs. |
| 114 | */ |
| 115 | private static final char intToAltBase64[] = { |
| 116 | '!', '"', '#', '$', '%', '&', '\'', '(', ')', ',', '-', '.', ':', |
| 117 | ';', '<', '>', '@', '[', ']', '^', '`', '_', '{', '|', '}', '~', |
| 118 | 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', |
| 119 | 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', |
| 120 | '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '?' |
| 121 | }; |
| 122 | |
| 123 | /** |
| 124 | * Translates the specified Base64 string (as per Preferences.get(byte[])) |
| 125 | * into a byte array. |
| 126 | * |
| 127 | * @throw IllegalArgumentException if <tt>s</tt> is not a valid Base64 |
| 128 | * string. |
| 129 | */ |
| 130 | static byte[] base64ToByteArray(String s) { |
| 131 | return base64ToByteArray(s, false); |
| 132 | } |
| 133 | |
| 134 | /** |
| 135 | * Translates the specified "alternate representation" Base64 string |
| 136 | * into a byte array. |
| 137 | * |
| 138 | * @throw IllegalArgumentException or ArrayOutOfBoundsException |
| 139 | * if <tt>s</tt> is not a valid alternate representation |
| 140 | * Base64 string. |
| 141 | */ |
| 142 | static byte[] altBase64ToByteArray(String s) { |
| 143 | return base64ToByteArray(s, true); |
| 144 | } |
| 145 | |
| 146 | private static byte[] base64ToByteArray(String s, boolean alternate) { |
| 147 | byte[] alphaToInt = (alternate ? altBase64ToInt : base64ToInt); |
| 148 | int sLen = s.length(); |
| 149 | int numGroups = sLen/4; |
| 150 | if (4*numGroups != sLen) |
| 151 | throw new IllegalArgumentException( |
| 152 | "String length must be a multiple of four."); |
| 153 | int missingBytesInLastGroup = 0; |
| 154 | int numFullGroups = numGroups; |
| 155 | if (sLen != 0) { |
| 156 | if (s.charAt(sLen-1) == '=') { |
| 157 | missingBytesInLastGroup++; |
| 158 | numFullGroups--; |
| 159 | } |
| 160 | if (s.charAt(sLen-2) == '=') |
| 161 | missingBytesInLastGroup++; |
| 162 | } |
| 163 | byte[] result = new byte[3*numGroups - missingBytesInLastGroup]; |
| 164 | |
| 165 | // Translate all full groups from base64 to byte array elements |
| 166 | int inCursor = 0, outCursor = 0; |
| 167 | for (int i=0; i<numFullGroups; i++) { |
| 168 | int ch0 = base64toInt(s.charAt(inCursor++), alphaToInt); |
| 169 | int ch1 = base64toInt(s.charAt(inCursor++), alphaToInt); |
| 170 | int ch2 = base64toInt(s.charAt(inCursor++), alphaToInt); |
| 171 | int ch3 = base64toInt(s.charAt(inCursor++), alphaToInt); |
| 172 | result[outCursor++] = (byte) ((ch0 << 2) | (ch1 >> 4)); |
| 173 | result[outCursor++] = (byte) ((ch1 << 4) | (ch2 >> 2)); |
| 174 | result[outCursor++] = (byte) ((ch2 << 6) | ch3); |
| 175 | } |
| 176 | |
| 177 | // Translate partial group, if present |
| 178 | if (missingBytesInLastGroup != 0) { |
| 179 | int ch0 = base64toInt(s.charAt(inCursor++), alphaToInt); |
| 180 | int ch1 = base64toInt(s.charAt(inCursor++), alphaToInt); |
| 181 | result[outCursor++] = (byte) ((ch0 << 2) | (ch1 >> 4)); |
| 182 | |
| 183 | if (missingBytesInLastGroup == 1) { |
| 184 | int ch2 = base64toInt(s.charAt(inCursor++), alphaToInt); |
| 185 | result[outCursor++] = (byte) ((ch1 << 4) | (ch2 >> 2)); |
| 186 | } |
| 187 | } |
| 188 | // assert inCursor == s.length()-missingBytesInLastGroup; |
| 189 | // assert outCursor == result.length; |
| 190 | return result; |
| 191 | } |
| 192 | |
| 193 | /** |
| 194 | * Translates the specified character, which is assumed to be in the |
| 195 | * "Base 64 Alphabet" into its equivalent 6-bit positive integer. |
| 196 | * |
| 197 | * @throw IllegalArgumentException or ArrayOutOfBoundsException if |
| 198 | * c is not in the Base64 Alphabet. |
| 199 | */ |
| 200 | private static int base64toInt(char c, byte[] alphaToInt) { |
| 201 | int result = alphaToInt[c]; |
| 202 | if (result < 0) |
| 203 | throw new IllegalArgumentException("Illegal character " + c); |
| 204 | return result; |
| 205 | } |
| 206 | |
| 207 | /** |
| 208 | * This array is a lookup table that translates unicode characters |
| 209 | * drawn from the "Base64 Alphabet" (as specified in Table 1 of RFC 2045) |
| 210 | * into their 6-bit positive integer equivalents. Characters that |
| 211 | * are not in the Base64 alphabet but fall within the bounds of the |
| 212 | * array are translated to -1. |
| 213 | */ |
| 214 | private static final byte base64ToInt[] = { |
| 215 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| 216 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| 217 | -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54, |
| 218 | 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, |
| 219 | 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, |
| 220 | 24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, |
| 221 | 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51 |
| 222 | }; |
| 223 | |
| 224 | /** |
| 225 | * This array is the analogue of base64ToInt, but for the nonstandard |
| 226 | * variant that avoids the use of uppercase alphabetic characters. |
| 227 | */ |
| 228 | private static final byte altBase64ToInt[] = { |
| 229 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| 230 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, |
| 231 | 2, 3, 4, 5, 6, 7, 8, -1, 62, 9, 10, 11, -1 , 52, 53, 54, 55, 56, 57, |
| 232 | 58, 59, 60, 61, 12, 13, 14, -1, 15, 63, 16, -1, -1, -1, -1, -1, -1, |
| 233 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| 234 | -1, -1, -1, 17, -1, 18, 19, 21, 20, 26, 27, 28, 29, 30, 31, 32, 33, |
| 235 | 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, |
| 236 | 51, 22, 23, 24, 25 |
| 237 | }; |
| 238 | |
| 239 | public static void main(String args[]) { |
| 240 | int numRuns = Integer.parseInt(args[0]); |
| 241 | int numBytes = Integer.parseInt(args[1]); |
| 242 | java.util.Random rnd = new java.util.Random(); |
| 243 | for (int i=0; i<numRuns; i++) { |
| 244 | for (int j=0; j<numBytes; j++) { |
| 245 | byte[] arr = new byte[j]; |
| 246 | for (int k=0; k<j; k++) |
| 247 | arr[k] = (byte)rnd.nextInt(); |
| 248 | |
| 249 | String s = byteArrayToBase64(arr); |
| 250 | byte [] b = base64ToByteArray(s); |
| 251 | if (!java.util.Arrays.equals(arr, b)) |
| 252 | System.out.println("Dismal failure!"); |
| 253 | |
| 254 | s = byteArrayToAltBase64(arr); |
| 255 | b = altBase64ToByteArray(s); |
| 256 | if (!java.util.Arrays.equals(arr, b)) |
| 257 | System.out.println("Alternate dismal failure!"); |
| 258 | } |
| 259 | } |
| 260 | } |
| 261 | } |