1 // ================================================================================================= 2 // ADOBE SYSTEMS INCORPORATED 3 // Copyright 2001 Adobe Systems Incorporated 4 // All Rights Reserved 5 // 6 // NOTICE: Adobe permits you to use, modify, and distribute this file in accordance with the terms 7 // of the Adobe license agreement accompanying it. 8 // ================================================================================================= 9 10 package com.adobe.xmp.impl; 11 12 13 14 15 /** 16 * A utility class to perform base64 encoding and decoding as specified 17 * in RFC-1521. See also RFC 1421. 18 * 19 * @version $Revision: 1.4 $ 20 */ 21 public class Base64 22 { 23 /** marker for invalid bytes */ 24 private static final byte INVALID = -1; 25 /** marker for accepted whitespace bytes */ 26 private static final byte WHITESPACE = -2; 27 /** marker for an equal symbol */ 28 private static final byte EQUAL = -3; 29 30 /** */ 31 private static byte[] base64 = { 32 (byte) 'A', (byte) 'B', (byte) 'C', (byte) 'D', // 0 to 3 33 (byte) 'E', (byte) 'F', (byte) 'G', (byte) 'H', // 4 to 7 34 (byte) 'I', (byte) 'J', (byte) 'K', (byte) 'L', // 8 to 11 35 (byte) 'M', (byte) 'N', (byte) 'O', (byte) 'P', // 11 to 15 36 (byte) 'Q', (byte) 'R', (byte) 'S', (byte) 'T', // 16 to 19 37 (byte) 'U', (byte) 'V', (byte) 'W', (byte) 'X', // 20 to 23 38 (byte) 'Y', (byte) 'Z', (byte) 'a', (byte) 'b', // 24 to 27 39 (byte) 'c', (byte) 'd', (byte) 'e', (byte) 'f', // 28 to 31 40 (byte) 'g', (byte) 'h', (byte) 'i', (byte) 'j', // 32 to 35 41 (byte) 'k', (byte) 'l', (byte) 'm', (byte) 'n', // 36 to 39 42 (byte) 'o', (byte) 'p', (byte) 'q', (byte) 'r', // 40 to 43 43 (byte) 's', (byte) 't', (byte) 'u', (byte) 'v', // 44 to 47 44 (byte) 'w', (byte) 'x', (byte) 'y', (byte) 'z', // 48 to 51 45 (byte) '0', (byte) '1', (byte) '2', (byte) '3', // 52 to 55 46 (byte) '4', (byte) '5', (byte) '6', (byte) '7', // 56 to 59 47 (byte) '8', (byte) '9', (byte) '+', (byte) '/' // 60 to 63 48 }; 49 /** */ 50 private static byte[] ascii = new byte[255]; 51 /** */ 52 static { 53 // not valid bytes 54 for (int idx = 0; idx < 255; idx++) 55 { 56 ascii[idx] = INVALID; 57 } 58 // valid bytes 59 for (int idx = 0; idx < base64.length; idx++) 60 { 61 ascii[base64[idx]] = (byte) idx; 62 } 63 // whitespaces 64 ascii[0x09] = WHITESPACE; 65 ascii[0x0A] = WHITESPACE; 66 ascii[0x0D] = WHITESPACE; 67 ascii[0x20] = WHITESPACE; 68 69 // trailing equals 70 ascii[0x3d] = EQUAL; 71 } 72 73 74 /** 75 * Encode the given byte[]. 76 * 77 * @param src the source string. 78 * @return the base64-encoded data. 79 */ encode(byte[] src)80 public static final byte[] encode(byte[] src) 81 { 82 return encode(src, 0); 83 } 84 85 86 /** 87 * Encode the given byte[]. 88 * 89 * @param src the source string. 90 * @param lineFeed a linefeed is added after <code>linefeed</code> characters; 91 * must be dividable by four; 0 means no linefeeds 92 * @return the base64-encoded data. 93 */ encode(byte[] src, int lineFeed)94 public static final byte[] encode(byte[] src, int lineFeed) 95 { 96 // linefeed must be dividable by 4 97 lineFeed = lineFeed / 4 * 4; 98 if (lineFeed < 0) 99 { 100 lineFeed = 0; 101 } 102 103 // determine code length 104 int codeLength = ((src.length + 2) / 3) * 4; 105 if (lineFeed > 0) 106 { 107 codeLength += (codeLength - 1) / lineFeed; 108 } 109 110 byte[] dst = new byte[codeLength]; 111 int bits24; 112 int bits6; 113 // 114 // Do 3-byte to 4-byte conversion + 0-63 to ascii printable conversion 115 // 116 int didx = 0; 117 int sidx = 0; 118 int lf = 0; 119 while (sidx + 3 <= src.length) 120 { 121 bits24 = (src[sidx++] & 0xFF) << 16; 122 bits24 |= (src[sidx++] & 0xFF) << 8; 123 bits24 |= (src[sidx++] & 0xFF) << 0; 124 bits6 = (bits24 & 0x00FC0000) >> 18; 125 dst[didx++] = base64[bits6]; 126 bits6 = (bits24 & 0x0003F000) >> 12; 127 dst[didx++] = base64[bits6]; 128 bits6 = (bits24 & 0x00000FC0) >> 6; 129 dst[didx++] = base64[bits6]; 130 bits6 = (bits24 & 0x0000003F); 131 dst[didx++] = base64[bits6]; 132 133 lf += 4; 134 if (didx < codeLength && lineFeed > 0 && lf % lineFeed == 0) 135 { 136 dst[didx++] = 0x0A; 137 } 138 } 139 if (src.length - sidx == 2) 140 { 141 bits24 = (src[sidx ] & 0xFF) << 16; 142 bits24 |= (src[sidx + 1] & 0xFF) << 8; 143 bits6 = (bits24 & 0x00FC0000) >> 18; 144 dst[didx++] = base64[bits6]; 145 bits6 = (bits24 & 0x0003F000) >> 12; 146 dst[didx++] = base64[bits6]; 147 bits6 = (bits24 & 0x00000FC0) >> 6; 148 dst[didx++] = base64[bits6]; 149 dst[didx++] = (byte) '='; 150 } 151 else if (src.length - sidx == 1) 152 { 153 bits24 = (src[sidx] & 0xFF) << 16; 154 bits6 = (bits24 & 0x00FC0000) >> 18; 155 dst[didx++] = base64[bits6]; 156 bits6 = (bits24 & 0x0003F000) >> 12; 157 dst[didx++] = base64[bits6]; 158 dst[didx++] = (byte) '='; 159 dst[didx++] = (byte) '='; 160 } 161 return dst; 162 } 163 164 165 /** 166 * Encode the given string. 167 * @param src the source string. 168 * @return the base64-encoded string. 169 */ encode(String src)170 public static final String encode(String src) 171 { 172 return new String(encode(src.getBytes())); 173 } 174 175 176 /** 177 * Decode the given byte[]. 178 * 179 * @param src 180 * the base64-encoded data. 181 * @return the decoded data. 182 * @throws IllegalArgumentException Thrown if the base 64 strings contains non-valid characters, 183 * beside the bas64 chars, LF, CR, tab and space are accepted. 184 */ decode(byte[] src)185 public static final byte[] decode(byte[] src) throws IllegalArgumentException 186 { 187 // 188 // Do ascii printable to 0-63 conversion. 189 // 190 int sidx; 191 int srcLen = 0; 192 for (sidx = 0; sidx < src.length; sidx++) 193 { 194 byte val = ascii[src[sidx]]; 195 if (val >= 0) 196 { 197 src[srcLen++] = val; 198 } 199 else if (val == INVALID) 200 { 201 throw new IllegalArgumentException("Invalid base 64 string"); 202 } 203 } 204 205 // 206 // Trim any padding. 207 // 208 while (srcLen > 0 && src[srcLen - 1] == EQUAL) 209 { 210 srcLen--; 211 } 212 byte[] dst = new byte[srcLen * 3 / 4]; 213 214 // 215 // Do 4-byte to 3-byte conversion. 216 // 217 int didx; 218 for (sidx = 0, didx = 0; didx < dst.length - 2; sidx += 4, didx += 3) 219 { 220 dst[didx ] = (byte) (((src[sidx ] << 2) & 0xFF) 221 | ((src[sidx + 1] >>> 4) & 0x03)); 222 dst[didx + 1] = (byte) (((src[sidx + 1] << 4) & 0xFF) 223 | ((src[sidx + 2] >>> 2) & 0x0F)); 224 dst[didx + 2] = (byte) (((src[sidx + 2] << 6) & 0xFF) 225 | ((src[sidx + 3]) & 0x3F)); 226 } 227 if (didx < dst.length) 228 { 229 dst[didx] = (byte) (((src[sidx ] << 2) & 0xFF) 230 | ((src[sidx + 1] >>> 4) & 0x03)); 231 } 232 if (++didx < dst.length) 233 { 234 dst[didx] = (byte) (((src[sidx + 1] << 4) & 0xFF) 235 | ((src[sidx + 2] >>> 2) & 0x0F)); 236 } 237 return dst; 238 } 239 240 241 /** 242 * Decode the given string. 243 * 244 * @param src the base64-encoded string. 245 * @return the decoded string. 246 */ decode(String src)247 public static final String decode(String src) 248 { 249 return new String(decode(src.getBytes())); 250 } 251 } 252