Source code
Description: source: package: org.apache.commons.codec.binary, class: Base32, class: Builder

    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      https://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017
    018package org.apache.commons.codec.binary;
    019
    020import java.util.Arrays;
    021
    022import org.apache.commons.codec.CodecPolicy;
    023
    024/**
    025 * Provides Base32 encoding and decoding as defined by <a href="https://www.ietf.org/rfc/rfc4648.txt">RFC 4648</a>.
    026 *
    027 * <p>
    028 * The class can be parameterized in the following manner with various constructors:
    029 * </p>
    030 * <ul>
    031 * <li>Whether to use the "base32hex" variant instead of the default "base32"</li>
    032 * <li>Line length: Default 76. Line length that aren't multiples of 8 will still essentially end up being multiples of 8 in the encoded data.
    033 * <li>Line separator: Default is CRLF ("\r\n")</li>
    034 * </ul>
    035 * <p>
    036 * This class operates directly on byte streams, and not character streams.
    037 * </p>
    038 * <p>
    039 * This class is thread-safe.
    040 * </p>
    041 * <p>
    042 * To configure a new instance, use a {@link Builder}. For example:
    043 * </p>
    044 * <pre>
    045 * Base32 base32 = Base32.builder()
    046 *   .setDecodingPolicy(DecodingPolicy.LENIENT) // default is lenient
    047 *   .setLineLength(0)                          // default is none
    048 *   .setLineSeparator('\r', '\n')              // default is CR LF
    049 *   .setPadding('=')                           // default is '='
    050 *   .setEncodeTable(customEncodeTable)         // default is RFC 4648 Section 6, Table 3: The Base 32 Alphabet
    051 *   .get()
    052 * </pre>
    053 *
    054 * @see Base32InputStream
    055 * @see Base32OutputStream
    056 * @see <a href="https://www.ietf.org/rfc/rfc4648.txt">RFC 4648</a>
    057 * @since 1.5
    058 */
    059public class Base32 extends BaseNCodec {
    060
    061    /**
    062     * Builds {@link Base32} instances.
    063     *
    064     * <p>
    065     * To configure a new instance, use a {@link Builder}. For example:
    066     * </p>
    067     *
    068     * <pre>
    069     * Base32 base32 = Base32.builder()
    070     *   .setDecodingPolicy(DecodingPolicy.LENIENT) // default is lenient
    071     *   .setLineLength(0)                          // default is none
    072     *   .setLineSeparator('\r', '\n')              // default is CR LF
    073     *   .setPadding('=')                           // default is '='
    074     *   .setEncodeTable(customEncodeTable)         // default is RFC 4648 Section 6, Table 3: The Base 32 Alphabet
    075     *   .get()
    076     * </pre>
    077     *
    078     * @since 1.17.0
    079     */
    080    public static class Builder extends AbstractBuilder<Base32, Builder> {
    081
    082        /**
    083         * Constructs a new instance using <a href="https://datatracker.ietf.org/doc/html/rfc4648#section-6">RFC 4648 Section 6, Table 3: The Base 32
    084         * Alphabet</a>.
    085         */
    086        public Builder() {
    087            super(ENCODE_TABLE);
    088            setDecodeTableRaw(DECODE_TABLE);
    089            setEncodeTableRaw(ENCODE_TABLE);
    090            setEncodedBlockSize(BYTES_PER_ENCODED_BLOCK);
    091            setUnencodedBlockSize(BYTES_PER_UNENCODED_BLOCK);
    092        }
    093
    094        @Override
    095        public Base32 get() {
    096            return new Base32(this);
    097        }
    098
    099        /**
    100         * Sets the encode table and derives the matching decode table.
    101         * <p>
    102         * The RFC 4648 Base32 and Base32 Hex tables keep their case-insensitive decoders.
    103         * </p>
    104         *
    105         * @param encodeTable The encode table with exactly 32 unique entries, null resets to the default.
    106         * @return {@code this} instance.
    107         * @throws IllegalArgumentException if the encode table does not contain exactly 32 unique entries.
    108         */
    109        @Override
    110        public Builder setEncodeTable(final byte... encodeTable) {
    111            super.setDecodeTableRaw(toDecodeTable(encodeTable));
    112            return super.setEncodeTable(encodeTable);
    113        }
    114
    115        /**
    116         * Sets the encode and decode tables to use Base32 hexadecimal if {@code true}, otherwise use the Base32 alphabet.
    117         * <p>
    118         * This overrides a value previously set with {@link #setEncodeTable(byte...)}.
    119         * </p>
    120         *
    121         * @param useHex use Base32 hexadecimal if {@code true}, otherwise use the Base32 alphabet.
    122         * @return {@code this} instance.
    123         * @since 1.18.0
    124         */
    125        public Builder setHexDecodeTable(final boolean useHex) {
    126            return setEncodeTable(encodeTable(useHex));
    127        }
    128
    129        /**
    130         * Sets the encode table to use Base32 hexadecimal if {@code true}, otherwise use the Base32 alphabet.
    131         * <p>
    132         * This overrides a value previously set with {@link #setEncodeTable(byte...)}.
    133         * </p>
    134         *
    135         * @param useHex
    136         *               <ul>
    137         *               <li>If true, then use <a href="https://datatracker.ietf.org/doc/html/rfc4648#section-7">RFC 4648 Section 7, Table 4: Base 32 Encoding
    138         *               with Extended Hex Alphabet</a></li>
    139         *               <li>If false, then use <a href="https://datatracker.ietf.org/doc/html/rfc4648#section-6">RFC 4648 Section 6, Table 3: The Base 32
    140         *               Alphabet</a></li>
    141         *               </ul>
    142         * @return {@code this} instance.
    143         * @since 1.18.0
    144         */
    145        public Builder setHexEncodeTable(final boolean useHex) {
    146            return setEncodeTable(encodeTable(useHex));
    147        }
    148    }
    149
    150    /**
    151     * BASE32 characters are 5 bits in length. They are formed by taking a block of five octets to form a 40-bit string, which is converted into eight BASE32
    152     * characters.
    153     */
    154    private static final int BITS_PER_ENCODED_BYTE = 5;
    155
    156    private static final int BYTES_PER_ENCODED_BLOCK = 8;
    157    private static final int BYTES_PER_UNENCODED_BLOCK = 5;
    158    private static final int DECODING_TABLE_LENGTH = 256;
    159    private static final int ENCODING_TABLE_LENGTH = 1 << BITS_PER_ENCODED_BYTE;
    160
    161    /**
    162     * This array is a lookup table that translates Unicode characters drawn from the "Base32 Alphabet" (as specified in Table 3 of RFC 4648) into their 5-bit
    163     * positive integer equivalents. Characters that are not in the Base32 alphabet but fall within the bounds of the array are translated to -1.
    164     */
    165    // @formatter:off
    166    private static final byte[] DECODE_TABLE = {
    167         //  0   1   2   3   4   5   6   7   8   9   A   B   C   D   E   F
    168            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 00-0f
    169            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 10-1f
    170            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 20-2f
    171            -1, -1, 26, 27, 28, 29, 30, 31, -1, -1, -1, -1, -1, -1, -1, -1, // 30-3f 2-7
    172            -1,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, // 40-4f A-O
    173            15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,                     // 50-5a P-Z
    174                                                        -1, -1, -1, -1, -1, // 5b-5f
    175            -1,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, // 60-6f a-o
    176            15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,                     // 70-7a p-z
    177    };
    178    // @formatter:on
    179
    180    /**
    181     * This array is a lookup table that translates 5-bit positive integer index values into their "Base32 Alphabet" equivalents as specified in
    182     * <a href="https://datatracker.ietf.org/doc/html/rfc4648#section-6">RFC 4648 Section 6, Table 3: The Base 32 Alphabet</a>.
    183     *
    184     * @see <a href="https://datatracker.ietf.org/doc/html/rfc4648#section-6">RFC 4648 Section 6, Table 3: The Base 32 Alphabet</a>
    185     */
    186    // @formatter:off
    187    private static final byte[] ENCODE_TABLE = {
    188            'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
    189            'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
    190            '2', '3', '4', '5', '6', '7',
    191    };
    192    // @formatter:on
    193
    194    /**
    195     * This array is a lookup table that translates Unicode characters drawn from the "Base32 Hex Alphabet" (as specified in Table 4 of RFC 4648) into their
    196     * 5-bit positive integer equivalents. Characters that are not in the Base32 Hex alphabet but fall within the bounds of the array are translated to -1.
    197     */
    198    // @formatter:off
    199    private static final byte[] HEX_DECODE_TABLE = {
    200         //  0   1   2   3   4   5   6   7   8   9   A   B   C   D   E   F
    201            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 00-0f
    202            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 10-1f
    203            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 20-2f
    204             0,  1,  2,  3,  4,  5,  6,  7,  8,  9, -1, -1, -1, -1, -1, -1, // 30-3f 0-9
    205            -1, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, // 40-4f A-O
    206            25, 26, 27, 28, 29, 30, 31,                                     // 50-56 P-V
    207                                        -1, -1, -1, -1, -1, -1, -1, -1, -1, // 57-5f
    208            -1, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, // 60-6f a-o
    209            25, 26, 27, 28, 29, 30, 31                                      // 70-76 p-v
    210    };
    211    // @formatter:on
    212
    213    /**
    214     * This array is a lookup table that translates 5-bit positive integer index values into their "Base 32 Encoding with Extended Hex Alphabet" equivalents as
    215     * specified in <a href="https://datatracker.ietf.org/doc/html/rfc4648#section-7">RFC 4648 Section 7, Table 4: Base 32 Encoding with Extended Hex
    216     * Alphabet</a>.
    217     *
    218     * @see <a href="https://datatracker.ietf.org/doc/html/rfc4648#section-7">RFC 4648 Section 7, Table 4: Base 32 Encoding with Extended Hex Alphabet</a>
    219     */
    220    // @formatter:off
    221    private static final byte[] HEX_ENCODE_TABLE = {
    222            '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
    223            'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
    224            'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V',
    225    };
    226    // @formatter:on
    227
    228    /** Mask used to extract 5 bits, used when encoding Base32 bytes */
    229    private static final int MASK_5_BITS = 0x1f;
    230
    231    /** Mask used to extract 4 bits, used when decoding final trailing character. */
    232    private static final long MASK_4_BITS = 0x0fL;
    233
    234    /** Mask used to extract 3 bits, used when decoding final trailing character. */
    235    private static final long MASK_3_BITS = 0x07L;
    236
    237    /** Mask used to extract 2 bits, used when decoding final trailing character. */
    238    private static final long MASK_2_BITS = 0x03L;
    239
    240    /** Mask used to extract 1 bits, used when decoding final trailing character. */
    241    private static final long MASK_1_BITS = 0x01L;
    242
    243    // The static final fields above are used for the original static byte[] methods on Base32.
    244    // The private member fields below are used with the new streaming approach, which requires
    245    // some state be preserved between calls of encode() and decode().
    246
    247    /**
    248     * Creates a new Builder.
    249     *
    250     * <p>
    251     * To configure a new instance, use a {@link Builder}. For example:
    252     * </p>
    253     *
    254     * <pre>
    255     * Base32 base32 = Base32.builder()
    256     *   .setDecodingPolicy(DecodingPolicy.LENIENT) // default is lenient
    257     *   .setLineLength(0)                          // default is none
    258     *   .setLineSeparator('\r', '\n')              // default is CR LF
    259     *   .setPadding('=')                           // default is '='
    260     *   .setEncodeTable(customEncodeTable)         // default is RFC 4648 Section 6, Table 3: The Base 32 Alphabet
    261     *   .get()
    262     * </pre>
    263     *
    264     * @return A new Builder.
    265     * @since 1.17.0
    266     */
    267    public static Builder builder() {
    268        return new Builder();
    269    }
    270
    271    /**
    272     * Calculates a decode table for a given encode table.
    273     *
    274     * @param encodeTable that is used to determine decode lookup table.
    275     * @return A new decode table.
    276     * @throws IllegalArgumentException if the encode table does not contain exactly 32 unique entries.
    277     */
    278    private static byte[] calculateDecodeTable(final byte[] encodeTable) {
    279        if (encodeTable.length != ENCODING_TABLE_LENGTH) {
    280            throw new IllegalArgumentException("encodeTable must have exactly 32 entries.");
    281        }
    282        final byte[] decodeTable = new byte[DECODING_TABLE_LENGTH];
    283        Arrays.fill(decodeTable, (byte) -1);
    284        for (int i = 0; i < encodeTable.length; i++) {
    285            final int encodedByte = encodeTable[i] & 0xff;
    286            if (decodeTable[encodedByte] != -1) {
    287                throw new IllegalArgumentException("encodeTable must not contain duplicate entries.");
    288            }
    289            decodeTable[encodedByte] = (byte) i;
    290        }
    291        return decodeTable;
    292    }
    293
    294    private static byte[] decodeTable(final boolean useHex) {
    295        return useHex ? HEX_DECODE_TABLE : DECODE_TABLE;
    296    }
    297
    298    /**
    299     * Gets the encoding table that matches {@code useHex}.
    300     *
    301     * @param useHex
    302     *               <ul>
    303     *               <li>If true, then use <a href="https://datatracker.ietf.org/doc/html/rfc4648#section-7">RFC 4648 Section 7, Table 4: Base 32 Encoding with
    304     *               Extended Hex Alphabet</a></li>
    305     *               <li>If false, then use <a href="https://datatracker.ietf.org/doc/html/rfc4648#section-6">RFC 4648 Section 6, Table 3: The Base 32
    306     *               Alphabet</a></li>
    307     *               </ul>
    308     * @return The encoding table that matches {@code useHex}.
    309     */
    310    private static byte[] encodeTable(final boolean useHex) {
    311        return useHex ? HEX_ENCODE_TABLE : ENCODE_TABLE;
    312    }
    313
    314    /**
    315     * Gets the decode table that matches the given encode table.
    316     *
    317     * @param encodeTable that is used to determine decode lookup table.
    318     * @return The matching decode table.
    319     */
    320    private static byte[] toDecodeTable(final byte[] encodeTable) {
    321        final byte[] table = encodeTable != null ? encodeTable : ENCODE_TABLE;
    322        if (Arrays.equals(table, ENCODE_TABLE)) {
    323            return DECODE_TABLE;
    324        }
    325        if (Arrays.equals(table, HEX_ENCODE_TABLE)) {
    326            return HEX_DECODE_TABLE;
    327        }
    328        return calculateDecodeTable(table);
    329    }
    330
    331    /**
    332     * Convenience variable to help us determine when our buffer is going to run out of room and needs resizing. {@code encodeSize = {@link
    333     * #BYTES_PER_ENCODED_BLOCK} + lineSeparator.length;}
    334     */
    335    private final int encodeSize;
    336
    337    /**
    338     * Line separator for encoding. Not used when decoding. Only used if lineLength &gt; 0.
    339     */
    340    private final byte[] lineSeparator;
    341
    342    /**
    343     * Constructs a Base32 codec used for decoding and encoding.
    344     * <p>
    345     * When encoding the line length is 0 (no chunking).
    346     * </p>
    347     */
    348    public Base32() {
    349        this(false);
    350    }
    351
    352    /**
    353     * Constructs a Base32 codec used for decoding and encoding.
    354     * <p>
    355     * When encoding the line length is 0 (no chunking).
    356     * </p>
    357     *
    358     * @param useHex
    359     *               <ul>
    360     *               <li>If true, then use <a href="https://datatracker.ietf.org/doc/html/rfc4648#section-7">RFC 4648 Section 7, Table 4: Base 32 Encoding with
    361     *               Extended Hex Alphabet</a></li>
    362     *               <li>If false, then use <a href="https://datatracker.ietf.org/doc/html/rfc4648#section-6">RFC 4648 Section 6, Table 3: The Base 32
    363     *               Alphabet</a></li>
    364     *               </ul>
    365     * @deprecated Use {@link #builder()} and {@link Builder}.
    366     */
    367    @Deprecated
    368    public Base32(final boolean useHex) {
    369        this(0, null, useHex, PAD_DEFAULT);
    370    }
    371
    372    /**
    373     * Constructs a Base32 codec used for decoding and encoding.
    374     * <p>
    375     * When encoding the line length is 0 (no chunking).
    376     * </p>
    377     *
    378     * @param useHex
    379     *               <ul>
    380     *               <li>If true, then use <a href="https://datatracker.ietf.org/doc/html/rfc4648#section-7">RFC 4648 Section 7, Table 4: Base 32 Encoding with
    381     *               Extended Hex Alphabet</a></li>
    382     *               <li>If false, then use <a href="https://datatracker.ietf.org/doc/html/rfc4648#section-6">RFC 4648 Section 6, Table 3: The Base 32
    383     *               Alphabet</a></li>
    384     *               </ul>
    385     * @param padding byte used as padding byte.
    386     * @deprecated Use {@link #builder()} and {@link Builder}.
    387     */
    388    @Deprecated
    389    public Base32(final boolean useHex, final byte padding) {
    390        this(0, null, useHex, padding);
    391    }
    392
    393    private Base32(final Builder builder) {
    394        super(builder);
    395        if (builder.getLineLength() > 0) {
    396            final byte[] lineSeparator = builder.getLineSeparator();
    397            // Must be done after initializing the tables
    398            if (containsAlphabetOrPad(lineSeparator)) {
    399                final String sep = StringUtils.newStringUtf8(lineSeparator);
    400                throw new IllegalArgumentException("lineSeparator must not contain Base32 characters: [" + sep + "]");
    401            }
    402            this.encodeSize = BYTES_PER_ENCODED_BLOCK + lineSeparator.length;
    403            this.lineSeparator = lineSeparator;
    404        } else {
    405            this.encodeSize = BYTES_PER_ENCODED_BLOCK;
    406            this.lineSeparator = null;
    407        }
    408        if (isInAlphabet(builder.getPadding()) || Character.isWhitespace(builder.getPadding())) {
    409            throw new IllegalArgumentException("pad must not be in alphabet or whitespace");
    410        }
    411    }
    412
    413    /**
    414     * Constructs a Base32 codec used for decoding and encoding.
    415     * <p>
    416     * When encoding the line length is 0 (no chunking).
    417     * </p>
    418     *
    419     * @param pad byte used as padding byte.
    420     * @deprecated Use {@link #builder()} and {@link Builder}.
    421     */
    422    @Deprecated
    423    public Base32(final byte pad) {
    424        this(false, pad);
    425    }
    426
    427    /**
    428     * Constructs a Base32 codec used for decoding and encoding.
    429     * <p>
    430     * When encoding the line length is given in the constructor, the line separator is CRLF.
    431     * </p>
    432     *
    433     * @param lineLength Each line of encoded data will be at most of the given length (rounded down to the nearest multiple of 8). If lineLength &lt;= 0, then
    434     *                   the output will not be divided into lines (chunks). Ignored when decoding.
    435     * @deprecated Use {@link #builder()} and {@link Builder}.
    436     */
    437    @Deprecated
    438    public Base32(final int lineLength) {
    439        this(lineLength, CHUNK_SEPARATOR);
    440    }
    441
    442    /**
    443     * Constructs a Base32 codec used for decoding and encoding.
    444     * <p>
    445     * When encoding the line length and line separator are given in the constructor.
    446     * </p>
    447     * <p>
    448     * Line lengths that aren't multiples of 8 will still essentially end up being multiples of 8 in the encoded data.
    449     * </p>
    450     *
    451     * @param lineLength    Each line of encoded data will be at most of the given length (rounded down to the nearest multiple of 8). If lineLength &lt;= 0,
    452     *                      then the output will not be divided into lines (chunks). Ignored when decoding.
    453     * @param lineSeparator Each line of encoded data will end with this sequence of bytes.
    454     * @throws IllegalArgumentException Thrown when the {@code lineSeparator} contains Base32 characters.
    455     * @deprecated Use {@link #builder()} and {@link Builder}.
    456     */
    457    @Deprecated
    458    public Base32(final int lineLength, final byte[] lineSeparator) {
    459        this(lineLength, lineSeparator, false, PAD_DEFAULT);
    460    }
    461
    462    /**
    463     * Constructs a Base32 / Base32 Hex codec used for decoding and encoding.
    464     * <p>
    465     * When encoding the line length and line separator are given in the constructor.
    466     * </p>
    467     * <p>
    468     * Line lengths that aren't multiples of 8 will still essentially end up being multiples of 8 in the encoded data.
    469     * </p>
    470     *
    471     * @param lineLength    Each line of encoded data will be at most of the given length (rounded down to the nearest multiple of 8). If lineLength &lt;= 0,
    472     *                      then the output will not be divided into lines (chunks). Ignored when decoding.
    473     * @param lineSeparator Each line of encoded data will end with this sequence of bytes.
    474     * @param useHex
    475     *               <ul>
    476     *               <li>If true, then use <a href="https://datatracker.ietf.org/doc/html/rfc4648#section-7">RFC 4648 Section 7, Table 4: Base 32 Encoding with
    477     *               Extended Hex Alphabet</a></li>
    478     *               <li>If false, then use <a href="https://datatracker.ietf.org/doc/html/rfc4648#section-6">RFC 4648 Section 6, Table 3: The Base 32
    479     *               Alphabet</a></li>
    480     *               </ul>
    481     * @throws IllegalArgumentException Thrown when the {@code lineSeparator} contains Base32 characters. Or the lineLength &gt; 0 and lineSeparator is null.
    482     * @deprecated Use {@link #builder()} and {@link Builder}.
    483     */
    484    @Deprecated
    485    public Base32(final int lineLength, final byte[] lineSeparator, final boolean useHex) {
    486        this(lineLength, lineSeparator, useHex, PAD_DEFAULT);
    487    }
    488
    489    /**
    490     * Constructs a Base32 / Base32 Hex codec used for decoding and encoding.
    491     * <p>
    492     * When encoding the line length and line separator are given in the constructor.
    493     * </p>
    494     * <p>
    495     * Line lengths that aren't multiples of 8 will still essentially end up being multiples of 8 in the encoded data.
    496     * </p>
    497     *
    498     * @param lineLength    Each line of encoded data will be at most of the given length (rounded down to the nearest multiple of 8). If lineLength &lt;= 0,
    499     *                      then the output will not be divided into lines (chunks). Ignored when decoding.
    500     * @param lineSeparator Each line of encoded data will end with this sequence of bytes.
    501     * @param useHex
    502     *               <ul>
    503     *               <li>If true, then use <a href="https://datatracker.ietf.org/doc/html/rfc4648#section-7">RFC 4648 Section 7, Table 4: Base 32 Encoding with
    504     *               Extended Hex Alphabet</a></li>
    505     *               <li>If false, then use <a href="https://datatracker.ietf.org/doc/html/rfc4648#section-6">RFC 4648 Section 6, Table 3: The Base 32
    506     *               Alphabet</a></li>
    507     *               </ul>
    508     * @param padding       padding byte.
    509     * @throws IllegalArgumentException Thrown when the {@code lineSeparator} contains Base32 characters. Or the lineLength &gt; 0 and lineSeparator is null.
    510     * @deprecated Use {@link #builder()} and {@link Builder}.
    511     */
    512    @Deprecated
    513    public Base32(final int lineLength, final byte[] lineSeparator, final boolean useHex, final byte padding) {
    514        this(lineLength, lineSeparator, useHex, padding, DECODING_POLICY_DEFAULT);
    515    }
    516
    517    /**
    518     * Constructs a Base32 / Base32 Hex codec used for decoding and encoding.
    519     * <p>
    520     * When encoding the line length and line separator are given in the constructor.
    521     * </p>
    522     * <p>
    523     * Line lengths that aren't multiples of 8 will still essentially end up being multiples of 8 in the encoded data.
    524     * </p>
    525     *
    526     * @param lineLength     Each line of encoded data will be at most of the given length (rounded down to the nearest multiple of 8). If lineLength &lt;= 0,
    527     *                       then the output will not be divided into lines (chunks). Ignored when decoding.
    528     * @param lineSeparator  Each line of encoded data will end with this sequence of bytes.
    529     * @param useHex
    530     *               <ul>
    531     *               <li>If true, then use <a href="https://datatracker.ietf.org/doc/html/rfc4648#section-7">RFC 4648 Section 7, Table 4: Base 32 Encoding with
    532     *               Extended Hex Alphabet</a></li>
    533     *               <li>If false, then use <a href="https://datatracker.ietf.org/doc/html/rfc4648#section-6">RFC 4648 Section 6, Table 3: The Base 32
    534     *               Alphabet</a></li>
    535     *               </ul>
    536     * @param padding        padding byte.
    537     * @param decodingPolicy The decoding policy.
    538     * @throws IllegalArgumentException Thrown when the {@code lineSeparator} contains Base32 characters. Or the lineLength &gt; 0 and lineSeparator is null.
    539     * @since 1.15
    540     * @deprecated Use {@link #builder()} and {@link Builder}.
    541     */
    542    @Deprecated
    543    public Base32(final int lineLength, final byte[] lineSeparator, final boolean useHex, final byte padding, final CodecPolicy decodingPolicy) {
    544        // @formatter:off
    545        this(builder()
    546                .setLineLength(lineLength)
    547                .setLineSeparator(lineSeparator != null ? lineSeparator : EMPTY_BYTE_ARRAY)
    548                .setDecodeTable(decodeTable(useHex))
    549                .setEncodeTableRaw(encodeTable(useHex))
    550                .setPadding(padding)
    551                .setDecodingPolicy(decodingPolicy));
    552        // @formatter:on
    553    }
    554
    555    /**
    556     * <p>
    557     * Decodes all of the provided data, starting at inPos, for inAvail bytes. Should be called at least twice: once with the data to decode, and once with
    558     * inAvail set to "-1" to alert decoder that EOF has been reached. The "-1" call is not necessary when decoding, but it doesn't hurt, either.
    559     * </p>
    560     * <p>
    561     * Ignores all non-Base32 characters. This is how chunked (for example 76 character) data is handled, since CR and LF are silently ignored, but has implications
    562     * for other bytes, too. This method subscribes to the garbage-in, garbage-out philosophy: it will not check the provided data for validity.
    563     * </p>
    564     * <p>
    565     * Output is written to {@link org.apache.commons.codec.binary.BaseNCodec.Context#buffer Context#buffer} as 8-bit octets, using
    566     * {@link org.apache.commons.codec.binary.BaseNCodec.Context#pos Context#pos} as the buffer position
    567     * </p>
    568     *
    569     * @param input   byte[] array of ASCII data to Base32 decode.
    570     * @param inPos   Position to start reading data from.
    571     * @param inAvail Amount of bytes available from input for decoding.
    572     * @param context The context to be used.
    573     */
    574    @Override
    575    void decode(final byte[] input, int inPos, final int inAvail, final Context context) {
    576        // package protected for access from I/O streams
    577        if (context.eof) {
    578            return;
    579        }
    580        if (inAvail < 0) {
    581            context.eof = true;
    582        }
    583        final int decodeSize = this.encodeSize - 1;
    584        for (int i = 0; i < inAvail; i++) {
    585            final int b = input[inPos++] & 0xff;
    586            if (b == (pad & 0xff)) {
    587                // We're done.
    588                context.eof = true;
    589                break;
    590            }
    591            final byte[] buffer = ensureBufferSize(decodeSize, context);
    592            if (b < this.decodeTable.length) {
    593                final int result = this.decodeTable[b];
    594                if (result >= 0) {
    595                    context.modulus = (context.modulus + 1) % BYTES_PER_ENCODED_BLOCK;
    596                    // collect decoded bytes
    597                    context.lbitWorkArea = (context.lbitWorkArea << BITS_PER_ENCODED_BYTE) + result;
    598                    if (context.modulus == 0) { // we can output the 5 bytes
    599                        buffer[context.pos++] = (byte) (context.lbitWorkArea >> 32 & MASK_8BITS);
    600                        buffer[context.pos++] = (byte) (context.lbitWorkArea >> 24 & MASK_8BITS);
    601                        buffer[context.pos++] = (byte) (context.lbitWorkArea >> 16 & MASK_8BITS);
    602                        buffer[context.pos++] = (byte) (context.lbitWorkArea >> 8 & MASK_8BITS);
    603                        buffer[context.pos++] = (byte) (context.lbitWorkArea & MASK_8BITS);
    604                    }
    605                }
    606            }
    607        }
    608        // Two forms of EOF as far as Base32 decoder is concerned: actual
    609        // EOF (-1) and first time '=' character is encountered in stream.
    610        // This approach makes the '=' padding characters completely optional.
    611        if (context.eof && context.modulus > 0) { // if modulus == 0, nothing to do
    612            final byte[] buffer = ensureBufferSize(decodeSize, context);
    613            // We ignore partial bytes, i.e. only multiples of 8 count.
    614            // Any combination not part of a valid encoding is either partially decoded
    615            // or will raise an exception. Possible trailing characters are 2, 4, 5, 7.
    616            // It is not possible to encode with 1, 3, 6 trailing characters.
    617            // For backwards compatibility 3 & 6 chars are decoded anyway rather than discarded.
    618            // See the encode(byte[]) method EOF section.
    619            switch (context.modulus) {
    620//              case 0 : // impossible, as excluded above
    621            case 1: // 5 bits - either ignore entirely, or raise an exception
    622                validateTrailingCharacters();
    623                // falls-through
    624            case 2: // 10 bits, drop 2 and output one byte
    625                validateCharacter(MASK_2_BITS, context);
    626                buffer[context.pos++] = (byte) (context.lbitWorkArea >> 2 & MASK_8BITS);
    627                break;
    628            case 3: // 15 bits, drop 7 and output 1 byte, or raise an exception
    629                validateTrailingCharacters();
    630                // Not possible from a valid encoding but decode anyway
    631                buffer[context.pos++] = (byte) (context.lbitWorkArea >> 7 & MASK_8BITS);
    632                break;
    633            case 4: // 20 bits = 2*8 + 4
    634                validateCharacter(MASK_4_BITS, context);
    635                context.lbitWorkArea = context.lbitWorkArea >> 4; // drop 4 bits
    636                buffer[context.pos++] = (byte) (context.lbitWorkArea >> 8 & MASK_8BITS);
    637                buffer[context.pos++] = (byte) (context.lbitWorkArea & MASK_8BITS);
    638                break;
    639            case 5: // 25 bits = 3*8 + 1
    640                validateCharacter(MASK_1_BITS, context);
    641                context.lbitWorkArea = context.lbitWorkArea >> 1;
    642                buffer[context.pos++] = (byte) (context.lbitWorkArea >> 16 & MASK_8BITS);
    643                buffer[context.pos++] = (byte) (context.lbitWorkArea >> 8 & MASK_8BITS);
    644                buffer[context.pos++] = (byte) (context.lbitWorkArea & MASK_8BITS);
    645                break;
    646            case 6: // 30 bits = 3*8 + 6, or raise an exception
    647                validateTrailingCharacters();
    648                // Not possible from a valid encoding but decode anyway
    649                context.lbitWorkArea = context.lbitWorkArea >> 6;
    650                buffer[context.pos++] = (byte) (context.lbitWorkArea >> 16 & MASK_8BITS);
    651                buffer[context.pos++] = (byte) (context.lbitWorkArea >> 8 & MASK_8BITS);
    652                buffer[context.pos++] = (byte) (context.lbitWorkArea & MASK_8BITS);
    653                break;
    654            case 7: // 35 bits = 4*8 +3
    655                validateCharacter(MASK_3_BITS, context);
    656                context.lbitWorkArea = context.lbitWorkArea >> 3;
    657                buffer[context.pos++] = (byte) (context.lbitWorkArea >> 24 & MASK_8BITS);
    658                buffer[context.pos++] = (byte) (context.lbitWorkArea >> 16 & MASK_8BITS);
    659                buffer[context.pos++] = (byte) (context.lbitWorkArea >> 8 & MASK_8BITS);
    660                buffer[context.pos++] = (byte) (context.lbitWorkArea & MASK_8BITS);
    661                break;
    662            default:
    663                // modulus can be 0-7, and we excluded 0,1 already
    664                throw new IllegalStateException("Impossible modulus " + context.modulus);
    665            }
    666        }
    667    }
    668
    669    /**
    670     * <p>
    671     * Encodes all of the provided data, starting at inPos, for inAvail bytes. Must be called at least twice: once with the data to encode, and once with
    672     * inAvail set to "-1" to alert encoder that EOF has been reached, so flush last remaining bytes (if not multiple of 5).
    673     * </p>
    674     *
    675     * @param input   byte[] array of binary data to Base32 encode.
    676     * @param inPos   Position to start reading data from.
    677     * @param inAvail Amount of bytes available from input for encoding.
    678     * @param context The context to be used.
    679     */
    680    @Override
    681    void encode(final byte[] input, int inPos, final int inAvail, final Context context) {
    682        // package protected for access from I/O streams
    683        if (context.eof) {
    684            return;
    685        }
    686        // inAvail < 0 is how we're informed of EOF in the underlying data we're
    687        // encoding.
    688        if (inAvail < 0) {
    689            context.eof = true;
    690            if (0 == context.modulus && lineLength == 0) {
    691                return; // no leftovers to process and not using chunking
    692            }
    693            final byte[] buffer = ensureBufferSize(encodeSize, context);
    694            final int savedPos = context.pos;
    695            switch (context.modulus) { // % 5
    696            case 0:
    697                break;
    698            case 1: // Only 1 octet; take top 5 bits then remainder
    699                buffer[context.pos++] = encodeTable[(int) (context.lbitWorkArea >> 3) & MASK_5_BITS]; // 8-1*5 = 3
    700                buffer[context.pos++] = encodeTable[(int) (context.lbitWorkArea << 2) & MASK_5_BITS]; // 5-3=2
    701                buffer[context.pos++] = pad;
    702                buffer[context.pos++] = pad;
    703                buffer[context.pos++] = pad;
    704                buffer[context.pos++] = pad;
    705                buffer[context.pos++] = pad;
    706                buffer[context.pos++] = pad;
    707                break;
    708            case 2: // 2 octets = 16 bits to use
    709                buffer[context.pos++] = encodeTable[(int) (context.lbitWorkArea >> 11) & MASK_5_BITS]; // 16-1*5 = 11
    710                buffer[context.pos++] = encodeTable[(int) (context.lbitWorkArea >> 6) & MASK_5_BITS]; // 16-2*5 = 6
    711                buffer[context.pos++] = encodeTable[(int) (context.lbitWorkArea >> 1) & MASK_5_BITS]; // 16-3*5 = 1
    712                buffer[context.pos++] = encodeTable[(int) (context.lbitWorkArea << 4) & MASK_5_BITS]; // 5-1 = 4
    713                buffer[context.pos++] = pad;
    714                buffer[context.pos++] = pad;
    715                buffer[context.pos++] = pad;
    716                buffer[context.pos++] = pad;
    717                break;
    718            case 3: // 3 octets = 24 bits to use
    719                buffer[context.pos++] = encodeTable[(int) (context.lbitWorkArea >> 19) & MASK_5_BITS]; // 24-1*5 = 19
    720                buffer[context.pos++] = encodeTable[(int) (context.lbitWorkArea >> 14) & MASK_5_BITS]; // 24-2*5 = 14
    721                buffer[context.pos++] = encodeTable[(int) (context.lbitWorkArea >> 9) & MASK_5_BITS]; // 24-3*5 = 9
    722                buffer[context.pos++] = encodeTable[(int) (context.lbitWorkArea >> 4) & MASK_5_BITS]; // 24-4*5 = 4
    723                buffer[context.pos++] = encodeTable[(int) (context.lbitWorkArea << 1) & MASK_5_BITS]; // 5-4 = 1
    724                buffer[context.pos++] = pad;
    725                buffer[context.pos++] = pad;
    726                buffer[context.pos++] = pad;
    727                break;
    728            case 4: // 4 octets = 32 bits to use
    729                buffer[context.pos++] = encodeTable[(int) (context.lbitWorkArea >> 27) & MASK_5_BITS]; // 32-1*5 = 27
    730                buffer[context.pos++] = encodeTable[(int) (context.lbitWorkArea >> 22) & MASK_5_BITS]; // 32-2*5 = 22
    731                buffer[context.pos++] = encodeTable[(int) (context.lbitWorkArea >> 17) & MASK_5_BITS]; // 32-3*5 = 17
    732                buffer[context.pos++] = encodeTable[(int) (context.lbitWorkArea >> 12) & MASK_5_BITS]; // 32-4*5 = 12
    733                buffer[context.pos++] = encodeTable[(int) (context.lbitWorkArea >> 7) & MASK_5_BITS]; // 32-5*5 = 7
    734                buffer[context.pos++] = encodeTable[(int) (context.lbitWorkArea >> 2) & MASK_5_BITS]; // 32-6*5 = 2
    735                buffer[context.pos++] = encodeTable[(int) (context.lbitWorkArea << 3) & MASK_5_BITS]; // 5-2 = 3
    736                buffer[context.pos++] = pad;
    737                break;
    738            default:
    739                throw new IllegalStateException("Impossible modulus " + context.modulus);
    740            }
    741            context.currentLinePos += context.pos - savedPos; // keep track of current line position
    742            // if currentPos == 0 we are at the start of a line, so don't add CRLF
    743            if (lineLength > 0 && context.currentLinePos > 0) { // add chunk separator if required
    744                System.arraycopy(lineSeparator, 0, buffer, context.pos, lineSeparator.length);
    745                context.pos += lineSeparator.length;
    746            }
    747        } else {
    748            for (int i = 0; i < inAvail; i++) {
    749                final byte[] buffer = ensureBufferSize(encodeSize, context);
    750                context.modulus = (context.modulus + 1) % BYTES_PER_UNENCODED_BLOCK;
    751                int b = input[inPos++];
    752                if (b < 0) {
    753                    b += 256;
    754                }
    755                context.lbitWorkArea = (context.lbitWorkArea << 8) + b; // BITS_PER_BYTE
    756                if (0 == context.modulus) { // we have enough bytes to create our output
    757                    buffer[context.pos++] = encodeTable[(int) (context.lbitWorkArea >> 35) & MASK_5_BITS];
    758                    buffer[context.pos++] = encodeTable[(int) (context.lbitWorkArea >> 30) & MASK_5_BITS];
    759                    buffer[context.pos++] = encodeTable[(int) (context.lbitWorkArea >> 25) & MASK_5_BITS];
    760                    buffer[context.pos++] = encodeTable[(int) (context.lbitWorkArea >> 20) & MASK_5_BITS];
    761                    buffer[context.pos++] = encodeTable[(int) (context.lbitWorkArea >> 15) & MASK_5_BITS];
    762                    buffer[context.pos++] = encodeTable[(int) (context.lbitWorkArea >> 10) & MASK_5_BITS];
    763                    buffer[context.pos++] = encodeTable[(int) (context.lbitWorkArea >> 5) & MASK_5_BITS];
    764                    buffer[context.pos++] = encodeTable[(int) context.lbitWorkArea & MASK_5_BITS];
    765                    context.currentLinePos += BYTES_PER_ENCODED_BLOCK;
    766                    if (lineLength > 0 && lineLength <= context.currentLinePos) {
    767                        System.arraycopy(lineSeparator, 0, buffer, context.pos, lineSeparator.length);
    768                        context.pos += lineSeparator.length;
    769                        context.currentLinePos = 0;
    770                    }
    771                }
    772            }
    773        }
    774    }
    775
    776    /**
    777     * Gets the line separator (for testing only).
    778     *
    779     * @return The line separator.
    780     */
    781    byte[] getLineSeparator() {
    782        return lineSeparator;
    783    }
    784
    785    /**
    786     * Returns whether or not the {@code octet} is in the Base32 alphabet.
    787     *
    788     * @param octet The value to test.
    789     * @return {@code true} if the value is defined in the Base32 alphabet {@code false} otherwise.
    790     */
    791    @Override
    792    public boolean isInAlphabet(final byte octet) {
    793        final int value = octet & 0xff;
    794        return value < decodeTable.length && decodeTable[value] != -1;
    795    }
    796
    797    /**
    798     * Validates whether decoding the final trailing character is possible in the context of the set of possible Base32 values.
    799     * <p>
    800     * The character is valid if the lower bits within the provided mask are zero. This is used to test the final trailing base-32 digit is zero in the bits
    801     * that will be discarded.
    802     * </p>
    803     *
    804     * @param emptyBitsMask The mask of the lower bits that should be empty.
    805     * @param context       The context to be used.
    806     * @throws IllegalArgumentException if the bits being checked contain any non-zero value.
    807     */
    808    private void validateCharacter(final long emptyBitsMask, final Context context) {
    809        // Use the long bit work area
    810        if (isStrictDecoding() && (context.lbitWorkArea & emptyBitsMask) != 0) {
    811            throw new IllegalArgumentException("Strict decoding: Last encoded character (before the paddings if any) is a valid " +
    812                    "Base32 alphabet but not a possible encoding. Expected the discarded bits from the character to be zero.");
    813        }
    814    }
    815
    816    /**
    817     * Validates whether decoding allows final trailing characters that cannot be created during encoding.
    818     *
    819     * @throws IllegalArgumentException if strict decoding is enabled.
    820     */
    821    private void validateTrailingCharacters() {
    822        if (isStrictDecoding()) {
    823            throw new IllegalArgumentException("Strict decoding: Last encoded character(s) (before the paddings if any) are valid " +
    824                    "Base32 alphabet but not a possible encoding. Decoding requires either 2, 4, 5, or 7 trailing 5-bit characters to create bytes.");
    825        }
    826    }
    827}