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1   /*
2    *  Licensed to the Apache Software Foundation (ASF) under one
3    *  or more contributor license agreements.  See the NOTICE file
4    *  distributed with this work for additional information
5    *  regarding copyright ownership.  The ASF licenses this file
6    *  to you under the Apache License, Version 2.0 (the
7    *  "License"); you may not use this file except in compliance
8    *  with the License.  You may obtain a copy of the License at
9    *
10   *    http://www.apache.org/licenses/LICENSE-2.0
11   *
12   *  Unless required by applicable law or agreed to in writing,
13   *  software distributed under the License is distributed on an
14   *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   *  KIND, either express or implied.  See the License for the
16   *  specific language governing permissions and limitations
17   *  under the License.
18   *
19   */
20  package org.apache.mina.util;
21  
22  import java.security.InvalidParameterException;
23  
24  /**
25   * Provides Base64 encoding and decoding as defined by RFC 2045.
26   * 
27   * <p>This class implements section <cite>6.8. Base64 Content-Transfer-Encoding</cite> 
28   * from RFC 2045 <cite>Multipurpose Internet Mail Extensions (MIME) Part One: 
29   * Format of Internet Message Bodies</cite> by Freed and Borenstein.</p> 
30   *
31   * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>
32   * 
33   *  This class was 
34   * @author Apache Software Foundation commons codec (http://commons.apache.org/codec/)
35   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
36   */
37  public class Base64 {
38  
39      /**
40       * Chunk size per RFC 2045 section 6.8.
41       * 
42       * <p>The {@value} character limit does not count the trailing CRLF, but counts 
43       * all other characters, including any equal signs.</p>
44       * 
45       * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 6.8</a>
46       */
47      static final int CHUNK_SIZE = 76;
48  
49      /**
50       * Chunk separator per RFC 2045 section 2.1.
51       * 
52       * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 2.1</a>
53       */
54      static final byte[] CHUNK_SEPARATOR = "\r\n".getBytes();
55  
56      /**
57       * The base length.
58       */
59      static final int BASELENGTH = 255;
60  
61      /**
62       * Lookup length.
63       */
64      static final int LOOKUPLENGTH = 64;
65  
66      /**
67       * Used to calculate the number of bits in a byte.
68       */
69      static final int EIGHTBIT = 8;
70  
71      /**
72       * Used when encoding something which has fewer than 24 bits.
73       */
74      static final int SIXTEENBIT = 16;
75  
76      /**
77       * Used to determine how many bits data contains.
78       */
79      static final int TWENTYFOURBITGROUP = 24;
80  
81      /**
82       * Used to get the number of Quadruples.
83       */
84      static final int FOURBYTE = 4;
85  
86      /**
87       * Used to test the sign of a byte.
88       */
89      static final int SIGN = -128;
90  
91      /**
92       * Byte used to pad output.
93       */
94      static final byte PAD = (byte) '=';
95  
96      // Create arrays to hold the base64 characters and a 
97      // lookup for base64 chars
98      private static byte[] base64Alphabet = new byte[BASELENGTH];
99  
100     private static byte[] lookUpBase64Alphabet = new byte[LOOKUPLENGTH];
101 
102     // Populating the lookup and character arrays
103     static {
104         for (int i = 0; i < BASELENGTH; i++) {
105             base64Alphabet[i] = (byte) -1;
106         }
107         for (int i = 'Z'; i >= 'A'; i--) {
108             base64Alphabet[i] = (byte) (i - 'A');
109         }
110         for (int i = 'z'; i >= 'a'; i--) {
111             base64Alphabet[i] = (byte) (i - 'a' + 26);
112         }
113         for (int i = '9'; i >= '0'; i--) {
114             base64Alphabet[i] = (byte) (i - '0' + 52);
115         }
116 
117         base64Alphabet['+'] = 62;
118         base64Alphabet['/'] = 63;
119 
120         for (int i = 0; i <= 25; i++) {
121             lookUpBase64Alphabet[i] = (byte) ('A' + i);
122         }
123 
124         for (int i = 26, j = 0; i <= 51; i++, j++) {
125             lookUpBase64Alphabet[i] = (byte) ('a' + j);
126         }
127 
128         for (int i = 52, j = 0; i <= 61; i++, j++) {
129             lookUpBase64Alphabet[i] = (byte) ('0' + j);
130         }
131 
132         lookUpBase64Alphabet[62] = (byte) '+';
133         lookUpBase64Alphabet[63] = (byte) '/';
134     }
135 
136     private static boolean isBase64(byte octect) {
137         if (octect == PAD) {
138             return true;
139         } else if (base64Alphabet[octect] == -1) {
140             return false;
141         } else {
142             return true;
143         }
144     }
145 
146     /**
147      * Tests a given byte array to see if it contains
148      * only valid characters within the Base64 alphabet.
149      *
150      * @param arrayOctect byte array to test
151      * @return true if all bytes are valid characters in the Base64
152      *         alphabet or if the byte array is empty; false, otherwise
153      */
154     public static boolean isArrayByteBase64(byte[] arrayOctect) {
155 
156         arrayOctect = discardWhitespace(arrayOctect);
157 
158         int length = arrayOctect.length;
159         if (length == 0) {
160             // shouldn't a 0 length array be valid base64 data?
161             // return false;
162             return true;
163         }
164         for (int i = 0; i < length; i++) {
165             if (!isBase64(arrayOctect[i])) {
166                 return false;
167             }
168         }
169         return true;
170     }
171 
172     /**
173      * Encodes binary data using the base64 algorithm but
174      * does not chunk the output.
175      *
176      * @param binaryData binary data to encode
177      * @return Base64 characters
178      */
179     public static byte[] encodeBase64(byte[] binaryData) {
180         return encodeBase64(binaryData, false);
181     }
182 
183     /**
184      * Encodes binary data using the base64 algorithm and chunks
185      * the encoded output into 76 character blocks
186      *
187      * @param binaryData binary data to encode
188      * @return Base64 characters chunked in 76 character blocks
189      */
190     public static byte[] encodeBase64Chunked(byte[] binaryData) {
191         return encodeBase64(binaryData, true);
192     }
193 
194     /**
195      * Decodes an Object using the base64 algorithm.  This method
196      * is provided in order to satisfy the requirements of the
197      * Decoder interface, and will throw a DecoderException if the
198      * supplied object is not of type byte[].
199      *
200      * @param pObject Object to decode
201      * @return An object (of type byte[]) containing the 
202      *         binary data which corresponds to the byte[] supplied.
203      * @throws InvalidParameterException if the parameter supplied is not
204      *                          of type byte[]
205      */
206     public Object decode(Object pObject) {
207         if (!(pObject instanceof byte[])) {
208             throw new InvalidParameterException("Parameter supplied to Base64 decode is not a byte[]");
209         }
210         return decode((byte[]) pObject);
211     }
212 
213     /**
214      * Decodes a byte[] containing containing
215      * characters in the Base64 alphabet.
216      *
217      * @param pArray A byte array containing Base64 character data
218      * @return a byte array containing binary data
219      */
220     public byte[] decode(byte[] pArray) {
221         return decodeBase64(pArray);
222     }
223 
224     /**
225      * Encodes binary data using the base64 algorithm, optionally
226      * chunking the output into 76 character blocks.
227      *
228      * @param binaryData Array containing binary data to encode.
229      * @param isChunked if isChunked is true this encoder will chunk
230      *                  the base64 output into 76 character blocks
231      * @return Base64-encoded data.
232      */
233     public static byte[] encodeBase64(byte[] binaryData, boolean isChunked) {
234         int lengthDataBits = binaryData.length * EIGHTBIT;
235         int fewerThan24bits = lengthDataBits % TWENTYFOURBITGROUP;
236         int numberTriplets = lengthDataBits / TWENTYFOURBITGROUP;
237         byte encodedData[] = null;
238         int encodedDataLength = 0;
239         int nbrChunks = 0;
240 
241         if (fewerThan24bits != 0) {
242             //data not divisible by 24 bit
243             encodedDataLength = (numberTriplets + 1) * 4;
244         } else {
245             // 16 or 8 bit
246             encodedDataLength = numberTriplets * 4;
247         }
248 
249         // If the output is to be "chunked" into 76 character sections, 
250         // for compliance with RFC 2045 MIME, then it is important to 
251         // allow for extra length to account for the separator(s)
252         if (isChunked) {
253 
254             nbrChunks = (CHUNK_SEPARATOR.length == 0 ? 0 : (int) Math.ceil((float) encodedDataLength / CHUNK_SIZE));
255             encodedDataLength += nbrChunks * CHUNK_SEPARATOR.length;
256         }
257 
258         encodedData = new byte[encodedDataLength];
259 
260         byte k = 0, l = 0, b1 = 0, b2 = 0, b3 = 0;
261 
262         int encodedIndex = 0;
263         int dataIndex = 0;
264         int i = 0;
265         int nextSeparatorIndex = CHUNK_SIZE;
266         int chunksSoFar = 0;
267 
268         //log.debug("number of triplets = " + numberTriplets);
269         for (i = 0; i < numberTriplets; i++) {
270             dataIndex = i * 3;
271             b1 = binaryData[dataIndex];
272             b2 = binaryData[dataIndex + 1];
273             b3 = binaryData[dataIndex + 2];
274 
275             //log.debug("b1= " + b1 +", b2= " + b2 + ", b3= " + b3);
276 
277             l = (byte) (b2 & 0x0f);
278             k = (byte) (b1 & 0x03);
279 
280             byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
281             byte val2 = ((b2 & SIGN) == 0) ? (byte) (b2 >> 4) : (byte) ((b2) >> 4 ^ 0xf0);
282             byte val3 = ((b3 & SIGN) == 0) ? (byte) (b3 >> 6) : (byte) ((b3) >> 6 ^ 0xfc);
283 
284             encodedData[encodedIndex] = lookUpBase64Alphabet[val1];
285             //log.debug( "val2 = " + val2 );
286             //log.debug( "k4   = " + (k<<4) );
287             //log.debug(  "vak  = " + (val2 | (k<<4)) );
288             encodedData[encodedIndex + 1] = lookUpBase64Alphabet[val2 | (k << 4)];
289             encodedData[encodedIndex + 2] = lookUpBase64Alphabet[(l << 2) | val3];
290             encodedData[encodedIndex + 3] = lookUpBase64Alphabet[b3 & 0x3f];
291 
292             encodedIndex += 4;
293 
294             // If we are chunking, let's put a chunk separator down.
295             if (isChunked) {
296                 // this assumes that CHUNK_SIZE % 4 == 0
297                 if (encodedIndex == nextSeparatorIndex) {
298                     System.arraycopy(CHUNK_SEPARATOR, 0, encodedData, encodedIndex, CHUNK_SEPARATOR.length);
299                     chunksSoFar++;
300                     nextSeparatorIndex = (CHUNK_SIZE * (chunksSoFar + 1)) + (chunksSoFar * CHUNK_SEPARATOR.length);
301                     encodedIndex += CHUNK_SEPARATOR.length;
302                 }
303             }
304         }
305 
306         // form integral number of 6-bit groups
307         dataIndex = i * 3;
308 
309         if (fewerThan24bits == EIGHTBIT) {
310             b1 = binaryData[dataIndex];
311             k = (byte) (b1 & 0x03);
312             //log.debug("b1=" + b1);
313             //log.debug("b1<<2 = " + (b1>>2) );
314             byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
315             encodedData[encodedIndex] = lookUpBase64Alphabet[val1];
316             encodedData[encodedIndex + 1] = lookUpBase64Alphabet[k << 4];
317             encodedData[encodedIndex + 2] = PAD;
318             encodedData[encodedIndex + 3] = PAD;
319         } else if (fewerThan24bits == SIXTEENBIT) {
320 
321             b1 = binaryData[dataIndex];
322             b2 = binaryData[dataIndex + 1];
323             l = (byte) (b2 & 0x0f);
324             k = (byte) (b1 & 0x03);
325 
326             byte val1 = ((b1 & SIGN) == 0) ? (byte) (b1 >> 2) : (byte) ((b1) >> 2 ^ 0xc0);
327             byte val2 = ((b2 & SIGN) == 0) ? (byte) (b2 >> 4) : (byte) ((b2) >> 4 ^ 0xf0);
328 
329             encodedData[encodedIndex] = lookUpBase64Alphabet[val1];
330             encodedData[encodedIndex + 1] = lookUpBase64Alphabet[val2 | (k << 4)];
331             encodedData[encodedIndex + 2] = lookUpBase64Alphabet[l << 2];
332             encodedData[encodedIndex + 3] = PAD;
333         }
334 
335         if (isChunked) {
336             // we also add a separator to the end of the final chunk.
337             if (chunksSoFar < nbrChunks) {
338                 System.arraycopy(CHUNK_SEPARATOR, 0, encodedData, encodedDataLength - CHUNK_SEPARATOR.length,
339                         CHUNK_SEPARATOR.length);
340             }
341         }
342 
343         return encodedData;
344     }
345 
346     /**
347      * Decodes Base64 data into octects
348      *
349      * @param base64Data Byte array containing Base64 data
350      * @return Array containing decoded data.
351      */
352     public static byte[] decodeBase64(byte[] base64Data) {
353         // RFC 2045 requires that we discard ALL non-Base64 characters
354         base64Data = discardNonBase64(base64Data);
355 
356         // handle the edge case, so we don't have to worry about it later
357         if (base64Data.length == 0) {
358             return new byte[0];
359         }
360 
361         int numberQuadruple = base64Data.length / FOURBYTE;
362         byte decodedData[] = null;
363         byte b1 = 0, b2 = 0, b3 = 0, b4 = 0, marker0 = 0, marker1 = 0;
364 
365         // Throw away anything not in base64Data
366 
367         int encodedIndex = 0;
368         int dataIndex = 0;
369         {
370             // this sizes the output array properly - rlw
371             int lastData = base64Data.length;
372             // ignore the '=' padding
373             while (base64Data[lastData - 1] == PAD) {
374                 if (--lastData == 0) {
375                     return new byte[0];
376                 }
377             }
378             decodedData = new byte[lastData - numberQuadruple];
379         }
380 
381         for (int i = 0; i < numberQuadruple; i++) {
382             dataIndex = i * 4;
383             marker0 = base64Data[dataIndex + 2];
384             marker1 = base64Data[dataIndex + 3];
385 
386             b1 = base64Alphabet[base64Data[dataIndex]];
387             b2 = base64Alphabet[base64Data[dataIndex + 1]];
388 
389             if (marker0 != PAD && marker1 != PAD) {
390                 //No PAD e.g 3cQl
391                 b3 = base64Alphabet[marker0];
392                 b4 = base64Alphabet[marker1];
393 
394                 decodedData[encodedIndex] = (byte) (b1 << 2 | b2 >> 4);
395                 decodedData[encodedIndex + 1] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
396                 decodedData[encodedIndex + 2] = (byte) (b3 << 6 | b4);
397             } else if (marker0 == PAD) {
398                 //Two PAD e.g. 3c[Pad][Pad]
399                 decodedData[encodedIndex] = (byte) (b1 << 2 | b2 >> 4);
400             } else if (marker1 == PAD) {
401                 //One PAD e.g. 3cQ[Pad]
402                 b3 = base64Alphabet[marker0];
403 
404                 decodedData[encodedIndex] = (byte) (b1 << 2 | b2 >> 4);
405                 decodedData[encodedIndex + 1] = (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
406             }
407             encodedIndex += 3;
408         }
409         return decodedData;
410     }
411 
412     /**
413      * Discards any whitespace from a base-64 encoded block.
414      *
415      * @param data The base-64 encoded data to discard the whitespace
416      * from.
417      * @return The data, less whitespace (see RFC 2045).
418      */
419     static byte[] discardWhitespace(byte[] data) {
420         byte groomedData[] = new byte[data.length];
421         int bytesCopied = 0;
422 
423         for (int i = 0; i < data.length; i++) {
424             switch (data[i]) {
425             case (byte) ' ':
426             case (byte) '\n':
427             case (byte) '\r':
428             case (byte) '\t':
429                 break;
430             default:
431                 groomedData[bytesCopied++] = data[i];
432             }
433         }
434 
435         byte packedData[] = new byte[bytesCopied];
436 
437         System.arraycopy(groomedData, 0, packedData, 0, bytesCopied);
438 
439         return packedData;
440     }
441 
442     /**
443      * Discards any characters outside of the base64 alphabet, per
444      * the requirements on page 25 of RFC 2045 - "Any characters
445      * outside of the base64 alphabet are to be ignored in base64
446      * encoded data."
447      *
448      * @param data The base-64 encoded data to groom
449      * @return The data, less non-base64 characters (see RFC 2045).
450      */
451     static byte[] discardNonBase64(byte[] data) {
452         byte groomedData[] = new byte[data.length];
453         int bytesCopied = 0;
454 
455         for (int i = 0; i < data.length; i++) {
456             if (isBase64(data[i])) {
457                 groomedData[bytesCopied++] = data[i];
458             }
459         }
460 
461         byte packedData[] = new byte[bytesCopied];
462 
463         System.arraycopy(groomedData, 0, packedData, 0, bytesCopied);
464 
465         return packedData;
466     }
467 
468     // Implementation of the Encoder Interface
469 
470     /**
471      * Encodes an Object using the base64 algorithm.  This method
472      * is provided in order to satisfy the requirements of the
473      * Encoder interface, and will throw an EncoderException if the
474      * supplied object is not of type byte[].
475      *
476      * @param pObject Object to encode
477      * @return An object (of type byte[]) containing the 
478      *         base64 encoded data which corresponds to the byte[] supplied.
479      * @throws InvalidParameterException if the parameter supplied is not
480      *                          of type byte[]
481      */
482     public Object encode(Object pObject) {
483         if (!(pObject instanceof byte[])) {
484             throw new InvalidParameterException("Parameter supplied to Base64 encode is not a byte[]");
485         }
486         return encode((byte[]) pObject);
487     }
488 
489     /**
490      * Encodes a byte[] containing binary data, into a byte[] containing
491      * characters in the Base64 alphabet.
492      *
493      * @param pArray a byte array containing binary data
494      * @return A byte array containing only Base64 character data
495      */
496     public byte[] encode(byte[] pArray) {
497         return encodeBase64(pArray, false);
498     }
499 
500 }