001 /* 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, 013 * software distributed under the License is distributed on an 014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 015 * KIND, either express or implied. See the License for the 016 * specific language governing permissions and limitations 017 * under the License. 018 * 019 */ 020 021 package org.apache.directory.shared.ldap.util; 022 023 import org.apache.directory.shared.i18n.I18n; 024 025 026 /** 027 * decoding of base64 characters to raw bytes. 028 * 029 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a> 030 * @version $Revision: 919765 $ 031 */ 032 public class Base64 033 { 034 035 /** 036 * passed data array. 037 * 038 * @param a_data 039 * the array of bytes to encode 040 * @return base64-coded character array. 041 */ 042 public static char[] encode( byte[] a_data ) 043 { 044 char[] l_out = new char[( ( a_data.length + 2 ) / 3 ) * 4]; 045 046 // 047 // 3 bytes encode to 4 chars. Output is always an even 048 // multiple of 4 characters. 049 // 050 for ( int ii = 0, l_index = 0; ii < a_data.length; ii += 3, l_index += 4 ) 051 { 052 boolean l_quad = false; 053 boolean l_trip = false; 054 055 int l_val = ( 0xFF & a_data[ii] ); 056 l_val <<= 8; 057 if ( ( ii + 1 ) < a_data.length ) 058 { 059 l_val |= ( 0xFF & a_data[ii + 1] ); 060 l_trip = true; 061 } 062 063 l_val <<= 8; 064 if ( ( ii + 2 ) < a_data.length ) 065 { 066 l_val |= ( 0xFF & a_data[ii + 2] ); 067 l_quad = true; 068 } 069 070 l_out[l_index + 3] = s_alphabet[( l_quad ? ( l_val & 0x3F ) : 64 )]; 071 l_val >>= 6; 072 l_out[l_index + 2] = s_alphabet[( l_trip ? ( l_val & 0x3F ) : 64 )]; 073 l_val >>= 6; 074 l_out[l_index + 1] = s_alphabet[l_val & 0x3F]; 075 l_val >>= 6; 076 l_out[l_index + 0] = s_alphabet[l_val & 0x3F]; 077 } 078 return l_out; 079 } 080 081 082 /** 083 * Decodes a BASE-64 encoded stream to recover the original data. White 084 * space before and after will be trimmed away, but no other manipulation of 085 * the input will be performed. As of version 1.2 this method will properly 086 * handle input containing junk characters (newlines and the like) rather 087 * than throwing an error. It does this by pre-parsing the input and 088 * generating from that a count of VALID input characters. 089 * 090 * @param a_data 091 * data to decode. 092 * @return the decoded binary data. 093 */ 094 public static byte[] decode( char[] data ) 095 { 096 // as our input could contain non-BASE64 data (newlines, 097 // whitespace of any sort, whatever) we must first adjust 098 // our count of USABLE data so that... 099 // (a) we don't misallocate the output array, and 100 // (b) think that we miscalculated our data length 101 // just because of extraneous throw-away junk 102 103 int tempLen = data.length; 104 105 for ( char c:data) 106 { 107 if ( ( c > 255 ) || s_codes[c] < 0 ) 108 { 109 --tempLen; // ignore non-valid chars and padding 110 } 111 } 112 // calculate required length: 113 // -- 3 bytes for every 4 valid base64 chars 114 // -- plus 2 bytes if there are 3 extra base64 chars, 115 // or plus 1 byte if there are 2 extra. 116 117 int l_len = ( tempLen / 4 ) * 3; 118 119 if ( ( tempLen % 4 ) == 3 ) 120 { 121 l_len += 2; 122 } 123 124 if ( ( tempLen % 4 ) == 2 ) 125 { 126 l_len += 1; 127 } 128 129 byte[] l_out = new byte[l_len]; 130 131 int l_shift = 0; // # of excess bits stored in accum 132 int l_accum = 0; // excess bits 133 int l_index = 0; 134 135 // we now go through the entire array (NOT using the 'tempLen' value) 136 for ( char c:data ) 137 { 138 int l_value = ( c > 255 ) ? -1 : s_codes[c]; 139 140 if ( l_value >= 0 ) // skip over non-code 141 { 142 l_accum <<= 6; // bits shift up by 6 each time thru 143 l_shift += 6; // loop, with new bits being put in 144 l_accum |= l_value; // at the bottom. whenever there 145 if ( l_shift >= 8 ) // are 8 or more shifted in, write them 146 { 147 l_shift -= 8; // out (from the top, leaving any excess 148 l_out[l_index++] = // at the bottom for next iteration. 149 ( byte ) ( ( l_accum >> l_shift ) & 0xff ); 150 } 151 } 152 // we will also have skipped processing a padding null byte ('=') 153 // here; 154 // these are used ONLY for padding to an even length and do not 155 // legally 156 // occur as encoded data. for this reason we can ignore the fact 157 // that 158 // no index++ operation occurs in that special case: the out[] array 159 // is 160 // initialized to all-zero bytes to start with and that works to our 161 // advantage in this combination. 162 } 163 164 // if there is STILL something wrong we just have to throw up now! 165 if ( l_index != l_out.length ) 166 { 167 throw new Error( I18n.err( I18n.ERR_04348, l_index, l_out.length ) ); 168 } 169 170 return l_out; 171 } 172 173 /** code characters for values 0..63 */ 174 private static char[] s_alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=" 175 .toCharArray(); 176 177 /** lookup table for converting base64 characters to value in range 0..63 */ 178 private static byte[] s_codes = new byte[256]; 179 180 static 181 { 182 for ( int ii = 0; ii < 256; ii++ ) 183 { 184 s_codes[ii] = -1; 185 } 186 187 for ( int ii = 'A'; ii <= 'Z'; ii++ ) 188 { 189 s_codes[ii] = ( byte ) ( ii - 'A' ); 190 } 191 192 for ( int ii = 'a'; ii <= 'z'; ii++ ) 193 { 194 s_codes[ii] = ( byte ) ( 26 + ii - 'a' ); 195 } 196 197 for ( int ii = '0'; ii <= '9'; ii++ ) 198 { 199 s_codes[ii] = ( byte ) ( 52 + ii - '0' ); 200 } 201 202 s_codes['+'] = 62; 203 s_codes['/'] = 63; 204 } 205 }