Base64Codec


1   /*
2    * Copyright (C) The MX4J Contributors.
3    * All rights reserved.
4    *
5    * This software is distributed under the terms of the MX4J License version 1.0.
6    * See the terms of the MX4J License in the documentation provided with this software.
7    */
8   
9   package mx4j.util;
10  
11  /**
12   * This class is copy/paste of Jakarta's Commons-Codec v1.1 <code>org.apache.commons.codec.binary.Base64</code>
13   * implementation.
14   * It is reproduced here because we don't want to require a new jar just to perform Base64 code/decoding.
15   *
16   * @version $Revision: 1.3 $
17   */
18  public class Base64Codec
19  {
20     static final int CHUNK_SIZE = 76;
21     static final byte[] CHUNK_SEPARATOR = "\n".getBytes();
22  
23     static final int BASELENGTH = 255;
24     static final int LOOKUPLENGTH = 64;
25     static final int TWENTYFOURBITGROUP = 24;
26     static final int EIGHTBIT = 8;
27     static final int SIXTEENBIT = 16;
28     static final int SIXBIT = 6;
29     static final int FOURBYTE = 4;
30     static final int SIGN = -128;
31     static final byte PAD = (byte)'=';
32  
33     private static byte[] base64Alphabet = new byte[BASELENGTH];
34     private static byte[] lookUpBase64Alphabet = new byte[LOOKUPLENGTH];
35  
36     static
37     {
38        for (int i = 0; i < BASELENGTH; i++)
39        {
40           base64Alphabet[i] = (byte)-1;
41        }
42        for (int i = 'Z'; i >= 'A'; i--)
43        {
44           base64Alphabet[i] = (byte)(i - 'A');
45        }
46        for (int i = 'z'; i >= 'a'; i--)
47        {
48           base64Alphabet[i] = (byte)(i - 'a' + 26);
49        }
50        for (int i = '9'; i >= '0'; i--)
51        {
52           base64Alphabet[i] = (byte)(i - '0' + 52);
53        }
54  
55        base64Alphabet['+'] = 62;
56        base64Alphabet['/'] = 63;
57  
58        for (int i = 0; i <= 25; i++)
59        {
60           lookUpBase64Alphabet[i] = (byte)('A' + i);
61        }
62  
63        for (int i = 26, j = 0; i <= 51; i++, j++)
64        {
65           lookUpBase64Alphabet[i] = (byte)('a' + j);
66        }
67  
68        for (int i = 52, j = 0; i <= 61; i++, j++)
69        {
70           lookUpBase64Alphabet[i] = (byte)('0' + j);
71        }
72  
73        lookUpBase64Alphabet[62] = (byte)'+';
74        lookUpBase64Alphabet[63] = (byte)'/';
75     }
76  
77     private Base64Codec()
78     {
79     }
80  
81     public static boolean isArrayByteBase64(byte[] arrayOctect)
82     {
83        arrayOctect = discardWhitespace(arrayOctect);
84  
85        int length = arrayOctect.length;
86        if (length == 0)
87        {
88           return true;
89        }
90        for (int i = 0; i < length; i++)
91        {
92           if (!isBase64(arrayOctect[i]))
93           {
94              return false;
95           }
96        }
97        return true;
98     }
99  
100    public static byte[] encodeBase64(byte[] binaryData)
101    {
102       return (encodeBase64(binaryData, false));
103    }
104 
105    public static byte[] decodeBase64(byte[] base64Data)
106    {
107       // RFC 2045 suggests line wrapping at (no more than) 76
108       // characters -- we may have embedded whitespace.
109       base64Data = discardWhitespace(base64Data);
110 
111       // handle the edge case, so we don't have to worry about it later
112       if (base64Data.length == 0)
113       {
114          return new byte[0];
115       }
116 
117       int numberQuadruple = base64Data.length / FOURBYTE;
118       byte decodedData[] = null;
119       byte b1 = 0, b2 = 0, b3 = 0, b4 = 0, marker0 = 0, marker1 = 0;
120 
121       // Throw away anything not in base64Data
122 
123       int encodedIndex = 0;
124       int dataIndex = 0;
125       {
126          // this sizes the output array properly - rlw
127          int lastData = base64Data.length;
128          // ignore the '=' padding
129          while (base64Data[lastData - 1] == PAD)
130          {
131             if (--lastData == 0)
132             {
133                return new byte[0];
134             }
135          }
136          decodedData = new byte[lastData - numberQuadruple];
137       }
138 
139       for (int i = 0; i < numberQuadruple; i++)
140       {
141          dataIndex = i * 4;
142          marker0 = base64Data[dataIndex + 2];
143          marker1 = base64Data[dataIndex + 3];
144 
145          b1 = base64Alphabet[base64Data[dataIndex]];
146          b2 = base64Alphabet[base64Data[dataIndex + 1]];
147 
148          if (marker0 != PAD && marker1 != PAD)
149          {
150             //No PAD e.g 3cQl
151             b3 = base64Alphabet[marker0];
152             b4 = base64Alphabet[marker1];
153 
154             decodedData[encodedIndex] = (byte)(b1 << 2 | b2 >> 4);
155             decodedData[encodedIndex + 1] =
156             (byte)(((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
157             decodedData[encodedIndex + 2] = (byte)(b3 << 6 | b4);
158          }
159          else if (marker0 == PAD)
160          {
161             //Two PAD e.g. 3c[Pad][Pad]
162             decodedData[encodedIndex] = (byte)(b1 << 2 | b2 >> 4);
163          }
164          else if (marker1 == PAD)
165          {
166             //One PAD e.g. 3cQ[Pad]
167             b3 = base64Alphabet[marker0];
168 
169             decodedData[encodedIndex] = (byte)(b1 << 2 | b2 >> 4);
170             decodedData[encodedIndex + 1] =
171             (byte)(((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
172          }
173          encodedIndex += 3;
174       }
175       return decodedData;
176    }
177 
178    private static byte[] encodeBase64Chunked(byte[] binaryData)
179    {
180       return (encodeBase64(binaryData, true));
181    }
182 
183    private static boolean isBase64(byte octect)
184    {
185       if (octect == PAD)
186       {
187          return true;
188       }
189       else if (base64Alphabet[octect] == -1)
190       {
191          return false;
192       }
193       else
194       {
195          return true;
196       }
197    }
198 
199    private static byte[] encodeBase64(byte[] binaryData, boolean isChunked)
200    {
201       int lengthDataBits = binaryData.length * EIGHTBIT;
202       int fewerThan24bits = lengthDataBits % TWENTYFOURBITGROUP;
203       int numberTriplets = lengthDataBits / TWENTYFOURBITGROUP;
204       byte encodedData[] = null;
205       int encodedDataLength = 0;
206       int nbrChunks = 0;
207 
208       if (fewerThan24bits != 0)
209       {
210          //data not divisible by 24 bit
211          encodedDataLength = (numberTriplets + 1) * 4;
212       }
213       else
214       {
215          // 16 or 8 bit
216          encodedDataLength = numberTriplets * 4;
217       }
218 
219       // If the output is to be "chunked" into 76 character sections,
220       // for compliance with RFC 2045 MIME, then it is important to
221       // allow for extra length to account for the separator(s)
222       if (isChunked)
223       {
224 
225          nbrChunks =
226          (CHUNK_SEPARATOR.length == 0
227           ? 0
228           : (int)Math.ceil((float)encodedDataLength / CHUNK_SIZE));
229          encodedDataLength += nbrChunks * CHUNK_SEPARATOR.length;
230       }
231 
232       encodedData = new byte[encodedDataLength];
233 
234       byte k = 0, l = 0, b1 = 0, b2 = 0, b3 = 0;
235 
236       int encodedIndex = 0;
237       int dataIndex = 0;
238       int i = 0;
239       int nextSeparatorIndex = CHUNK_SIZE;
240       int chunksSoFar = 0;
241 
242       //log.debug("number of triplets = " + numberTriplets);
243       for (i = 0; i < numberTriplets; i++)
244       {
245          dataIndex = i * 3;
246          b1 = binaryData[dataIndex];
247          b2 = binaryData[dataIndex + 1];
248          b3 = binaryData[dataIndex + 2];
249 
250          //log.debug("b1= " + b1 +", b2= " + b2 + ", b3= " + b3);
251 
252          l = (byte)(b2 & 0x0f);
253          k = (byte)(b1 & 0x03);
254 
255          byte val1 =
256                  ((b1 & SIGN) == 0)
257                  ? (byte)(b1 >> 2)
258                  : (byte)((b1) >> 2 ^ 0xc0);
259          byte val2 =
260                  ((b2 & SIGN) == 0)
261                  ? (byte)(b2 >> 4)
262                  : (byte)((b2) >> 4 ^ 0xf0);
263          byte val3 =
264                  ((b3 & SIGN) == 0)
265                  ? (byte)(b3 >> 6)
266                  : (byte)((b3) >> 6 ^ 0xfc);
267 
268          encodedData[encodedIndex] = lookUpBase64Alphabet[val1];
269          //log.debug( "val2 = " + val2 );
270          //log.debug( "k4   = " + (k<<4) );
271          //log.debug(  "vak  = " + (val2 | (k<<4)) );
272          encodedData[encodedIndex + 1] =
273          lookUpBase64Alphabet[val2 | (k << 4)];
274          encodedData[encodedIndex + 2] =
275          lookUpBase64Alphabet[(l << 2) | val3];
276          encodedData[encodedIndex + 3] = lookUpBase64Alphabet[b3 & 0x3f];
277 
278          encodedIndex += 4;
279 
280          // If we are chunking, let's put a chunk separator down.
281          if (isChunked)
282          {
283             // this assumes that CHUNK_SIZE % 4 == 0
284             if (encodedIndex == nextSeparatorIndex)
285             {
286                System.arraycopy(CHUNK_SEPARATOR,
287                                 0,
288                                 encodedData,
289                                 encodedIndex,
290                                 CHUNK_SEPARATOR.length);
291                chunksSoFar++;
292                nextSeparatorIndex =
293                (CHUNK_SIZE * (chunksSoFar + 1))
294                + (chunksSoFar * CHUNK_SEPARATOR.length);
295                encodedIndex += CHUNK_SEPARATOR.length;
296             }
297          }
298       }
299 
300       // form integral number of 6-bit groups
301       dataIndex = i * 3;
302 
303       if (fewerThan24bits == EIGHTBIT)
304       {
305          b1 = binaryData[dataIndex];
306          k = (byte)(b1 & 0x03);
307          //log.debug("b1=" + b1);
308          //log.debug("b1<<2 = " + (b1>>2) );
309          byte val1 =
310                  ((b1 & SIGN) == 0)
311                  ? (byte)(b1 >> 2)
312                  : (byte)((b1) >> 2 ^ 0xc0);
313          encodedData[encodedIndex] = lookUpBase64Alphabet[val1];
314          encodedData[encodedIndex + 1] = lookUpBase64Alphabet[k << 4];
315          encodedData[encodedIndex + 2] = PAD;
316          encodedData[encodedIndex + 3] = PAD;
317       }
318       else if (fewerThan24bits == SIXTEENBIT)
319       {
320 
321          b1 = binaryData[dataIndex];
322          b2 = binaryData[dataIndex + 1];
323          l = (byte)(b2 & 0x0f);
324          k = (byte)(b1 & 0x03);
325 
326          byte val1 =
327                  ((b1 & SIGN) == 0)
328                  ? (byte)(b1 >> 2)
329                  : (byte)((b1) >> 2 ^ 0xc0);
330          byte val2 =
331                  ((b2 & SIGN) == 0)
332                  ? (byte)(b2 >> 4)
333                  : (byte)((b2) >> 4 ^ 0xf0);
334 
335          encodedData[encodedIndex] = lookUpBase64Alphabet[val1];
336          encodedData[encodedIndex + 1] =
337          lookUpBase64Alphabet[val2 | (k << 4)];
338          encodedData[encodedIndex + 2] = lookUpBase64Alphabet[l << 2];
339          encodedData[encodedIndex + 3] = PAD;
340       }
341 
342       if (isChunked)
343       {
344          // we also add a separator to the end of the final chunk.
345          if (chunksSoFar < nbrChunks)
346          {
347             System.arraycopy(CHUNK_SEPARATOR,
348                              0,
349                              encodedData,
350                              encodedDataLength - CHUNK_SEPARATOR.length,
351                              CHUNK_SEPARATOR.length);
352          }
353       }
354 
355       return encodedData;
356    }
357 
358    private static byte[] discardWhitespace(byte[] data)
359    {
360       byte groomedData[] = new byte[data.length];
361       int bytesCopied = 0;
362 
363       for (int i = 0; i < data.length; i++)
364       {
365          switch (data[i])
366          {
367             case (byte)' ':
368             case (byte)'\n':
369             case (byte)'\r':
370             case (byte)'\t':
371                break;
372             default:
373                groomedData[bytesCopied++] = data[i];
374          }
375       }
376 
377       byte packedData[] = new byte[bytesCopied];
378 
379       System.arraycopy(groomedData, 0, packedData, 0, bytesCopied);
380 
381       return packedData;
382    }
383 }
384
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