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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  
18  package org.apache.commons.codec.binary;
19  
20  /**
21   * Provides Base32 encoding and decoding as defined by <a href="http://www.ietf.org/rfc/rfc4648.txt">RFC 4648</a>.
22   *
23   * <p>
24   * The class can be parameterized in the following manner with various constructors:
25   * </p>
26   * <ul>
27   * <li>Whether to use the "base32hex" variant instead of the default "base32"</li>
28   * <li>Line length: Default 76. Line length that aren't multiples of 8 will still essentially end up being multiples of
29   * 8 in the encoded data.
30   * <li>Line separator: Default is CRLF ("\r\n")</li>
31   * </ul>
32   * <p>
33   * This class operates directly on byte streams, and not character streams.
34   * </p>
35   * <p>
36   * This class is thread-safe.
37   * </p>
38   *
39   * @see <a href="http://www.ietf.org/rfc/rfc4648.txt">RFC 4648</a>
40   *
41   * @since 1.5
42   * @version $Id: Base32.java 1619949 2014-08-22 22:56:08Z ggregory $
43   */
44  public class Base32 extends BaseNCodec {
45  
46      /**
47       * BASE32 characters are 5 bits in length.
48       * They are formed by taking a block of five octets to form a 40-bit string,
49       * which is converted into eight BASE32 characters.
50       */
51      private static final int BITS_PER_ENCODED_BYTE = 5;
52      private static final int BYTES_PER_ENCODED_BLOCK = 8;
53      private static final int BYTES_PER_UNENCODED_BLOCK = 5;
54  
55      /**
56       * Chunk separator per RFC 2045 section 2.1.
57       *
58       * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 2.1</a>
59       */
60      private static final byte[] CHUNK_SEPARATOR = {'\r', '\n'};
61  
62      /**
63       * This array is a lookup table that translates Unicode characters drawn from the "Base32 Alphabet" (as specified
64       * in Table 3 of RFC 4648) into their 5-bit positive integer equivalents. Characters that are not in the Base32
65       * alphabet but fall within the bounds of the array are translated to -1.
66       */
67      private static final byte[] DECODE_TABLE = {
68           //  0   1   2   3   4   5   6   7   8   9   A   B   C   D   E   F
69              -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 00-0f
70              -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 10-1f
71              -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 20-2f
72              -1, -1, 26, 27, 28, 29, 30, 31, -1, -1, -1, -1, -1, -1, -1, -1, // 30-3f 2-7
73              -1,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, // 40-4f A-N
74              15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,                     // 50-5a O-Z
75      };
76  
77      /**
78       * This array is a lookup table that translates 5-bit positive integer index values into their "Base32 Alphabet"
79       * equivalents as specified in Table 3 of RFC 4648.
80       */
81      private static final byte[] ENCODE_TABLE = {
82              'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
83              'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
84              '2', '3', '4', '5', '6', '7',
85      };
86  
87      /**
88       * This array is a lookup table that translates Unicode characters drawn from the "Base32 |Hex Alphabet" (as
89       * specified in Table 3 of RFC 4648) into their 5-bit positive integer equivalents. Characters that are not in the
90       * Base32 Hex alphabet but fall within the bounds of the array are translated to -1.
91       */
92      private static final byte[] HEX_DECODE_TABLE = {
93           //  0   1   2   3   4   5   6   7   8   9   A   B   C   D   E   F
94              -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 00-0f
95              -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 10-1f
96              -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 20-2f
97               0,  1,  2,  3,  4,  5,  6,  7,  8,  9, -1, -1, -1, -1, -1, -1, // 30-3f 2-7
98              -1, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, // 40-4f A-N
99              25, 26, 27, 28, 29, 30, 31, 32,                                 // 50-57 O-V
100     };
101 
102     /**
103      * This array is a lookup table that translates 5-bit positive integer index values into their
104      * "Base32 Hex Alphabet" equivalents as specified in Table 3 of RFC 4648.
105      */
106     private static final byte[] HEX_ENCODE_TABLE = {
107             '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
108             'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
109             'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V',
110     };
111 
112     /** Mask used to extract 5 bits, used when encoding Base32 bytes */
113     private static final int MASK_5BITS = 0x1f;
114 
115     // The static final fields above are used for the original static byte[] methods on Base32.
116     // The private member fields below are used with the new streaming approach, which requires
117     // some state be preserved between calls of encode() and decode().
118 
119     /**
120      * Place holder for the bytes we're dealing with for our based logic.
121      * Bitwise operations store and extract the encoding or decoding from this variable.
122      */
123 
124     /**
125      * Convenience variable to help us determine when our buffer is going to run out of room and needs resizing.
126      * <code>decodeSize = {@link #BYTES_PER_ENCODED_BLOCK} - 1 + lineSeparator.length;</code>
127      */
128     private final int decodeSize;
129 
130     /**
131      * Decode table to use.
132      */
133     private final byte[] decodeTable;
134 
135     /**
136      * Convenience variable to help us determine when our buffer is going to run out of room and needs resizing.
137      * <code>encodeSize = {@link #BYTES_PER_ENCODED_BLOCK} + lineSeparator.length;</code>
138      */
139     private final int encodeSize;
140 
141     /**
142      * Encode table to use.
143      */
144     private final byte[] encodeTable;
145 
146     /**
147      * Line separator for encoding. Not used when decoding. Only used if lineLength &gt; 0.
148      */
149     private final byte[] lineSeparator;
150 
151     /**
152      * Creates a Base32 codec used for decoding and encoding.
153      * <p>
154      * When encoding the line length is 0 (no chunking).
155      * </p>
156      *
157      */
158     public Base32() {
159         this(false);
160     }
161 
162     /**
163      * Creates a Base32 codec used for decoding and encoding.
164      * <p>
165      * When encoding the line length is 0 (no chunking).
166      * </p>
167      * @param pad byte used as padding byte.
168      */
169     public Base32(final byte pad) {
170         this(false, pad);
171     }
172 
173     /**
174      * Creates a Base32 codec used for decoding and encoding.
175      * <p>
176      * When encoding the line length is 0 (no chunking).
177      * </p>
178      * @param useHex if {@code true} then use Base32 Hex alphabet
179      */
180     public Base32(final boolean useHex) {
181         this(0, null, useHex, PAD_DEFAULT);
182     }
183 
184     /**
185      * Creates a Base32 codec used for decoding and encoding.
186      * <p>
187      * When encoding the line length is 0 (no chunking).
188      * </p>
189      * @param useHex if {@code true} then use Base32 Hex alphabet
190      * @param pad byte used as padding byte.
191      */
192     public Base32(final boolean useHex, final byte pad) {
193         this(0, null, useHex, pad);
194     }
195 
196     /**
197      * Creates a Base32 codec used for decoding and encoding.
198      * <p>
199      * When encoding the line length is given in the constructor, the line separator is CRLF.
200      * </p>
201      *
202      * @param lineLength
203      *            Each line of encoded data will be at most of the given length (rounded down to nearest multiple of
204      *            8). If lineLength &lt;= 0, then the output will not be divided into lines (chunks). Ignored when
205      *            decoding.
206      */
207     public Base32(final int lineLength) {
208         this(lineLength, CHUNK_SEPARATOR);
209     }
210 
211     /**
212      * Creates a Base32 codec used for decoding and encoding.
213      * <p>
214      * When encoding the line length and line separator are given in the constructor.
215      * </p>
216      * <p>
217      * Line lengths that aren't multiples of 8 will still essentially end up being multiples of 8 in the encoded data.
218      * </p>
219      *
220      * @param lineLength
221      *            Each line of encoded data will be at most of the given length (rounded down to nearest multiple of
222      *            8). If lineLength &lt;= 0, then the output will not be divided into lines (chunks). Ignored when
223      *            decoding.
224      * @param lineSeparator
225      *            Each line of encoded data will end with this sequence of bytes.
226      * @throws IllegalArgumentException
227      *             The provided lineSeparator included some Base32 characters. That's not going to work!
228      */
229     public Base32(final int lineLength, final byte[] lineSeparator) {
230         this(lineLength, lineSeparator, false, PAD_DEFAULT);
231     }
232 
233     /**
234      * Creates a Base32 / Base32 Hex codec used for decoding and encoding.
235      * <p>
236      * When encoding the line length and line separator are given in the constructor.
237      * </p>
238      * <p>
239      * Line lengths that aren't multiples of 8 will still essentially end up being multiples of 8 in the encoded data.
240      * </p>
241      *
242      * @param lineLength
243      *            Each line of encoded data will be at most of the given length (rounded down to nearest multiple of
244      *            8). If lineLength &lt;= 0, then the output will not be divided into lines (chunks). Ignored when
245      *            decoding.
246      * @param lineSeparator
247      *            Each line of encoded data will end with this sequence of bytes.
248      * @param useHex
249      *            if {@code true}, then use Base32 Hex alphabet, otherwise use Base32 alphabet
250      * @throws IllegalArgumentException
251      *             The provided lineSeparator included some Base32 characters. That's not going to work! Or the
252      *             lineLength &gt; 0 and lineSeparator is null.
253      */
254     public Base32(final int lineLength, final byte[] lineSeparator, final boolean useHex) {
255         this(lineLength, lineSeparator, useHex, PAD_DEFAULT);
256     }
257 
258     /**
259      * Creates a Base32 / Base32 Hex codec used for decoding and encoding.
260      * <p>
261      * When encoding the line length and line separator are given in the constructor.
262      * </p>
263      * <p>
264      * Line lengths that aren't multiples of 8 will still essentially end up being multiples of 8 in the encoded data.
265      * </p>
266      *
267      * @param lineLength
268      *            Each line of encoded data will be at most of the given length (rounded down to nearest multiple of
269      *            8). If lineLength &lt;= 0, then the output will not be divided into lines (chunks). Ignored when
270      *            decoding.
271      * @param lineSeparator
272      *            Each line of encoded data will end with this sequence of bytes.
273      * @param useHex
274      *            if {@code true}, then use Base32 Hex alphabet, otherwise use Base32 alphabet
275      * @param pad byte used as padding byte.
276      * @throws IllegalArgumentException
277      *             The provided lineSeparator included some Base32 characters. That's not going to work! Or the
278      *             lineLength &gt; 0 and lineSeparator is null.
279      */
280     public Base32(final int lineLength, final byte[] lineSeparator, final boolean useHex, final byte pad) {
281         super(BYTES_PER_UNENCODED_BLOCK, BYTES_PER_ENCODED_BLOCK, lineLength,
282                 lineSeparator == null ? 0 : lineSeparator.length, pad);
283         if (useHex) {
284             this.encodeTable = HEX_ENCODE_TABLE;
285             this.decodeTable = HEX_DECODE_TABLE;
286         } else {
287             this.encodeTable = ENCODE_TABLE;
288             this.decodeTable = DECODE_TABLE;
289         }
290         if (lineLength > 0) {
291             if (lineSeparator == null) {
292                 throw new IllegalArgumentException("lineLength " + lineLength + " > 0, but lineSeparator is null");
293             }
294             // Must be done after initializing the tables
295             if (containsAlphabetOrPad(lineSeparator)) {
296                 final String sep = StringUtils.newStringUtf8(lineSeparator);
297                 throw new IllegalArgumentException("lineSeparator must not contain Base32 characters: [" + sep + "]");
298             }
299             this.encodeSize = BYTES_PER_ENCODED_BLOCK + lineSeparator.length;
300             this.lineSeparator = new byte[lineSeparator.length];
301             System.arraycopy(lineSeparator, 0, this.lineSeparator, 0, lineSeparator.length);
302         } else {
303             this.encodeSize = BYTES_PER_ENCODED_BLOCK;
304             this.lineSeparator = null;
305         }
306         this.decodeSize = this.encodeSize - 1;
307 
308         if (isInAlphabet(pad) || isWhiteSpace(pad)) {
309             throw new IllegalArgumentException("pad must not be in alphabet or whitespace");
310         }
311     }
312 
313     /**
314      * <p>
315      * Decodes all of the provided data, starting at inPos, for inAvail bytes. Should be called at least twice: once
316      * with the data to decode, and once with inAvail set to "-1" to alert decoder that EOF has been reached. The "-1"
317      * call is not necessary when decoding, but it doesn't hurt, either.
318      * </p>
319      * <p>
320      * Ignores all non-Base32 characters. This is how chunked (e.g. 76 character) data is handled, since CR and LF are
321      * silently ignored, but has implications for other bytes, too. This method subscribes to the garbage-in,
322      * garbage-out philosophy: it will not check the provided data for validity.
323      * </p>
324      *
325      * @param in
326      *            byte[] array of ascii data to Base32 decode.
327      * @param inPos
328      *            Position to start reading data from.
329      * @param inAvail
330      *            Amount of bytes available from input for encoding.
331      * @param context the context to be used
332      *
333      * Output is written to {@link Context#buffer} as 8-bit octets, using {@link Context#pos} as the buffer position
334      */
335     @Override
336     void decode(final byte[] in, int inPos, final int inAvail, final Context context) {
337         // package protected for access from I/O streams
338 
339         if (context.eof) {
340             return;
341         }
342         if (inAvail < 0) {
343             context.eof = true;
344         }
345         for (int i = 0; i < inAvail; i++) {
346             final byte b = in[inPos++];
347             if (b == pad) {
348                 // We're done.
349                 context.eof = true;
350                 break;
351             } else {
352                 final byte[] buffer = ensureBufferSize(decodeSize, context);
353                 if (b >= 0 && b < this.decodeTable.length) {
354                     final int result = this.decodeTable[b];
355                     if (result >= 0) {
356                         context.modulus = (context.modulus+1) % BYTES_PER_ENCODED_BLOCK;
357                         // collect decoded bytes
358                         context.lbitWorkArea = (context.lbitWorkArea << BITS_PER_ENCODED_BYTE) + result;
359                         if (context.modulus == 0) { // we can output the 5 bytes
360                             buffer[context.pos++] = (byte) ((context.lbitWorkArea >> 32) & MASK_8BITS);
361                             buffer[context.pos++] = (byte) ((context.lbitWorkArea >> 24) & MASK_8BITS);
362                             buffer[context.pos++] = (byte) ((context.lbitWorkArea >> 16) & MASK_8BITS);
363                             buffer[context.pos++] = (byte) ((context.lbitWorkArea >> 8) & MASK_8BITS);
364                             buffer[context.pos++] = (byte) (context.lbitWorkArea & MASK_8BITS);
365                         }
366                     }
367                 }
368             }
369         }
370 
371         // Two forms of EOF as far as Base32 decoder is concerned: actual
372         // EOF (-1) and first time '=' character is encountered in stream.
373         // This approach makes the '=' padding characters completely optional.
374         if (context.eof && context.modulus >= 2) { // if modulus < 2, nothing to do
375             final byte[] buffer = ensureBufferSize(decodeSize, context);
376 
377             //  we ignore partial bytes, i.e. only multiples of 8 count
378             switch (context.modulus) {
379                 case 2 : // 10 bits, drop 2 and output one byte
380                     buffer[context.pos++] = (byte) ((context.lbitWorkArea >> 2) & MASK_8BITS);
381                     break;
382                 case 3 : // 15 bits, drop 7 and output 1 byte
383                     buffer[context.pos++] = (byte) ((context.lbitWorkArea >> 7) & MASK_8BITS);
384                     break;
385                 case 4 : // 20 bits = 2*8 + 4
386                     context.lbitWorkArea = context.lbitWorkArea >> 4; // drop 4 bits
387                     buffer[context.pos++] = (byte) ((context.lbitWorkArea >> 8) & MASK_8BITS);
388                     buffer[context.pos++] = (byte) ((context.lbitWorkArea) & MASK_8BITS);
389                     break;
390                 case 5 : // 25bits = 3*8 + 1
391                     context.lbitWorkArea = context.lbitWorkArea >> 1;
392                     buffer[context.pos++] = (byte) ((context.lbitWorkArea >> 16) & MASK_8BITS);
393                     buffer[context.pos++] = (byte) ((context.lbitWorkArea >> 8) & MASK_8BITS);
394                     buffer[context.pos++] = (byte) ((context.lbitWorkArea) & MASK_8BITS);
395                     break;
396                 case 6 : // 30bits = 3*8 + 6
397                     context.lbitWorkArea = context.lbitWorkArea >> 6;
398                     buffer[context.pos++] = (byte) ((context.lbitWorkArea >> 16) & MASK_8BITS);
399                     buffer[context.pos++] = (byte) ((context.lbitWorkArea >> 8) & MASK_8BITS);
400                     buffer[context.pos++] = (byte) ((context.lbitWorkArea) & MASK_8BITS);
401                     break;
402                 case 7 : // 35 = 4*8 +3
403                     context.lbitWorkArea = context.lbitWorkArea >> 3;
404                     buffer[context.pos++] = (byte) ((context.lbitWorkArea >> 24) & MASK_8BITS);
405                     buffer[context.pos++] = (byte) ((context.lbitWorkArea >> 16) & MASK_8BITS);
406                     buffer[context.pos++] = (byte) ((context.lbitWorkArea >> 8) & MASK_8BITS);
407                     buffer[context.pos++] = (byte) ((context.lbitWorkArea) & MASK_8BITS);
408                     break;
409                 default:
410                     // modulus can be 0-7, and we excluded 0,1 already
411                     throw new IllegalStateException("Impossible modulus "+context.modulus);
412             }
413         }
414     }
415 
416     /**
417      * <p>
418      * Encodes all of the provided data, starting at inPos, for inAvail bytes. Must be called at least twice: once with
419      * the data to encode, and once with inAvail set to "-1" to alert encoder that EOF has been reached, so flush last
420      * remaining bytes (if not multiple of 5).
421      * </p>
422      *
423      * @param in
424      *            byte[] array of binary data to Base32 encode.
425      * @param inPos
426      *            Position to start reading data from.
427      * @param inAvail
428      *            Amount of bytes available from input for encoding.
429      * @param context the context to be used
430      */
431     @Override
432     void encode(final byte[] in, int inPos, final int inAvail, final Context context) {
433         // package protected for access from I/O streams
434 
435         if (context.eof) {
436             return;
437         }
438         // inAvail < 0 is how we're informed of EOF in the underlying data we're
439         // encoding.
440         if (inAvail < 0) {
441             context.eof = true;
442             if (0 == context.modulus && lineLength == 0) {
443                 return; // no leftovers to process and not using chunking
444             }
445             final byte[] buffer = ensureBufferSize(encodeSize, context);
446             final int savedPos = context.pos;
447             switch (context.modulus) { // % 5
448                 case 0 :
449                     break;
450                 case 1 : // Only 1 octet; take top 5 bits then remainder
451                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >> 3) & MASK_5BITS]; // 8-1*5 = 3
452                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea << 2) & MASK_5BITS]; // 5-3=2
453                     buffer[context.pos++] = pad;
454                     buffer[context.pos++] = pad;
455                     buffer[context.pos++] = pad;
456                     buffer[context.pos++] = pad;
457                     buffer[context.pos++] = pad;
458                     buffer[context.pos++] = pad;
459                     break;
460                 case 2 : // 2 octets = 16 bits to use
461                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >> 11) & MASK_5BITS]; // 16-1*5 = 11
462                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >>  6) & MASK_5BITS]; // 16-2*5 = 6
463                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >>  1) & MASK_5BITS]; // 16-3*5 = 1
464                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea <<  4) & MASK_5BITS]; // 5-1 = 4
465                     buffer[context.pos++] = pad;
466                     buffer[context.pos++] = pad;
467                     buffer[context.pos++] = pad;
468                     buffer[context.pos++] = pad;
469                     break;
470                 case 3 : // 3 octets = 24 bits to use
471                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >> 19) & MASK_5BITS]; // 24-1*5 = 19
472                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >> 14) & MASK_5BITS]; // 24-2*5 = 14
473                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >>  9) & MASK_5BITS]; // 24-3*5 = 9
474                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >>  4) & MASK_5BITS]; // 24-4*5 = 4
475                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea <<  1) & MASK_5BITS]; // 5-4 = 1
476                     buffer[context.pos++] = pad;
477                     buffer[context.pos++] = pad;
478                     buffer[context.pos++] = pad;
479                     break;
480                 case 4 : // 4 octets = 32 bits to use
481                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >> 27) & MASK_5BITS]; // 32-1*5 = 27
482                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >> 22) & MASK_5BITS]; // 32-2*5 = 22
483                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >> 17) & MASK_5BITS]; // 32-3*5 = 17
484                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >> 12) & MASK_5BITS]; // 32-4*5 = 12
485                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >>  7) & MASK_5BITS]; // 32-5*5 =  7
486                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >>  2) & MASK_5BITS]; // 32-6*5 =  2
487                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea <<  3) & MASK_5BITS]; // 5-2 = 3
488                     buffer[context.pos++] = pad;
489                     break;
490                 default:
491                     throw new IllegalStateException("Impossible modulus "+context.modulus);
492             }
493             context.currentLinePos += context.pos - savedPos; // keep track of current line position
494             // if currentPos == 0 we are at the start of a line, so don't add CRLF
495             if (lineLength > 0 && context.currentLinePos > 0){ // add chunk separator if required
496                 System.arraycopy(lineSeparator, 0, buffer, context.pos, lineSeparator.length);
497                 context.pos += lineSeparator.length;
498             }
499         } else {
500             for (int i = 0; i < inAvail; i++) {
501                 final byte[] buffer = ensureBufferSize(encodeSize, context);
502                 context.modulus = (context.modulus+1) % BYTES_PER_UNENCODED_BLOCK;
503                 int b = in[inPos++];
504                 if (b < 0) {
505                     b += 256;
506                 }
507                 context.lbitWorkArea = (context.lbitWorkArea << 8) + b; // BITS_PER_BYTE
508                 if (0 == context.modulus) { // we have enough bytes to create our output
509                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >> 35) & MASK_5BITS];
510                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >> 30) & MASK_5BITS];
511                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >> 25) & MASK_5BITS];
512                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >> 20) & MASK_5BITS];
513                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >> 15) & MASK_5BITS];
514                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >> 10) & MASK_5BITS];
515                     buffer[context.pos++] = encodeTable[(int)(context.lbitWorkArea >> 5) & MASK_5BITS];
516                     buffer[context.pos++] = encodeTable[(int)context.lbitWorkArea & MASK_5BITS];
517                     context.currentLinePos += BYTES_PER_ENCODED_BLOCK;
518                     if (lineLength > 0 && lineLength <= context.currentLinePos) {
519                         System.arraycopy(lineSeparator, 0, buffer, context.pos, lineSeparator.length);
520                         context.pos += lineSeparator.length;
521                         context.currentLinePos = 0;
522                     }
523                 }
524             }
525         }
526     }
527 
528     /**
529      * Returns whether or not the {@code octet} is in the Base32 alphabet.
530      *
531      * @param octet
532      *            The value to test
533      * @return {@code true} if the value is defined in the the Base32 alphabet {@code false} otherwise.
534      */
535     @Override
536     public boolean isInAlphabet(final byte octet) {
537         return octet >= 0 && octet < decodeTable.length && decodeTable[octet] != -1;
538     }
539 }