1/* 2 * Copyright (c) 2000, 2005, Oracle and/or its affiliates. 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. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26package 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 */ 36class 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} 262