    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 *      http://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.net.util;
    019
    020import java.io.UnsupportedEncodingException;
    021import java.math.BigInteger;
    022
    023
    024
    025/**
    026 * Provides Base64 encoding and decoding as defined by RFC 2045.
    027 *
    028 * <p>
    029 * This class implements section <cite>6.8. Base64 Content-Transfer-Encoding</cite> from RFC 2045 <cite>Multipurpose
    030 * Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies</cite> by Freed and Borenstein.
    031 * </p>
    032 * <p>
    033 * The class can be parameterized in the following manner with various constructors:
    034 * <ul>
    035 * <li>URL-safe mode: Default off.</li>
    036 * <li>Line length: Default 76. Line length that aren't multiples of 4 will still essentially end up being multiples of
    037 * 4 in the encoded data.
    038 * <li>Line separator: Default is CRLF ("\r\n")</li>
    039 * </ul>
    040 * <p>
    041 * Since this class operates directly on byte streams, and not character streams, it is hard-coded to only encode/decode
    042 * character encodings which are compatible with the lower 127 ASCII chart (ISO-8859-1, Windows-1252, UTF-8, etc).
    043 * </p>
    044 *
    045 * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>
    046 * @since 2.2
    047 */
    048public class Base64 {
    049    private static final int DEFAULT_BUFFER_RESIZE_FACTOR = 2;
    050
    051    private static final int DEFAULT_BUFFER_SIZE = 8192;
    052
    053    /**
    054     * Chunk size per RFC 2045 section 6.8.
    055     *
    056     * <p>
    057     * The {@value} character limit does not count the trailing CRLF, but counts all other characters, including any
    058     * equal signs.
    059     * </p>
    060     *
    061     * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 6.8</a>
    062     */
    063    static final int CHUNK_SIZE = 76;
    064
    065    /**
    066     * Chunk separator per RFC 2045 section 2.1.
    067     *
    068     * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 2.1</a>
    069     */
    070    private static final byte[] CHUNK_SEPARATOR = {'\r', '\n'};
    071
    072    private static final byte[] EMPTY_BYTE_ARRAY = new byte[0];
    073
    074    /**
    075     * This array is a lookup table that translates 6-bit positive integer index values into their "Base64 Alphabet"
    076     * equivalents as specified in Table 1 of RFC 2045.
    077     *
    078     * Thanks to "commons" project in ws.apache.org for this code.
    079     * http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
    080     */
    081    private static final byte[] STANDARD_ENCODE_TABLE = {
    082            'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
    083            'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
    084            'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
    085            'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
    086            '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'
    087    };
    088
    089    /**
    090     * This is a copy of the STANDARD_ENCODE_TABLE above, but with + and /
    091     * changed to - and _ to make the encoded Base64 results more URL-SAFE.
    092     * This table is only used when the Base64's mode is set to URL-SAFE.
    093     */
    094    private static final byte[] URL_SAFE_ENCODE_TABLE = {
    095            'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
    096            'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
    097            'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
    098            'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
    099            '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-', '_'
    100    };
    101
    102    /**
    103     * Byte used to pad output.
    104     */
    105    private static final byte PAD = '=';
    106
    107    /**
    108     * This array is a lookup table that translates Unicode characters drawn from the "Base64 Alphabet" (as specified in
    109     * Table 1 of RFC 2045) into their 6-bit positive integer equivalents. Characters that are not in the Base64
    110     * alphabet but fall within the bounds of the array are translated to -1.
    111     *
    112     * Note: '+' and '-' both decode to 62. '/' and '_' both decode to 63. This means decoder seamlessly handles both
    113     * URL_SAFE and STANDARD base64. (The encoder, on the other hand, needs to know ahead of time what to emit).
    114     *
    115     * Thanks to "commons" project in ws.apache.org for this code.
    116     * http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
    117     */
    118    private static final byte[] DECODE_TABLE = {
    119            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
    120            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
    121            -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, 62, -1, 63, 52, 53, 54,
    122            55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4,
    123            5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
    124            24, 25, -1, -1, -1, -1, 63, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34,
    125            35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51
    126    };
    127
    128    /** Mask used to extract 6 bits, used when encoding */
    129    private static final int MASK_6BITS = 0x3f;
    130
    131    /** Mask used to extract 8 bits, used in decoding base64 bytes */
    132    private static final int MASK_8BITS = 0xff;
    133
    134    // The static final fields above are used for the original static byte[] methods on Base64.
    135    // The private member fields below are used with the new streaming approach, which requires
    136    // some state be preserved between calls of encode() and decode().
    137
    138    /**
    139     * Encode table to use: either STANDARD or URL_SAFE. Note: the DECODE_TABLE above remains static because it is able
    140     * to decode both STANDARD and URL_SAFE streams, but the encodeTable must be a member variable so we can switch
    141     * between the two modes.
    142     */
    143    private final byte[] encodeTable;
    144
    145    /**
    146     * Line length for encoding. Not used when decoding. A value of zero or less implies no chunking of the base64
    147     * encoded data.
    148     */
    149    private final int lineLength;
    150
    151    /**
    152     * Line separator for encoding. Not used when decoding. Only used if lineLength > 0.
    153     */
    154    private final byte[] lineSeparator;
    155
    156    /**
    157     * Convenience variable to help us determine when our buffer is going to run out of room and needs resizing.
    158     * <code>decodeSize = 3 + lineSeparator.length;</code>
    159     */
    160    private final int decodeSize;
    161
    162    /**
    163     * Convenience variable to help us determine when our buffer is going to run out of room and needs resizing.
    164     * <code>encodeSize = 4 + lineSeparator.length;</code>
    165     */
    166    private final int encodeSize;
    167
    168    /**
    169     * Buffer for streaming.
    170     */
    171    private byte[] buffer;
    172
    173    /**
    174     * Position where next character should be written in the buffer.
    175     */
    176    private int pos;
    177
    178    /**
    179     * Position where next character should be read from the buffer.
    180     */
    181    private int readPos;
    182
    183    /**
    184     * Variable tracks how many characters have been written to the current line. Only used when encoding. We use it to
    185     * make sure each encoded line never goes beyond lineLength (if lineLength > 0).
    186     */
    187    private int currentLinePos;
    188
    189    /**
    190     * Writes to the buffer only occur after every 3 reads when encoding, an every 4 reads when decoding. This variable
    191     * helps track that.
    192     */
    193    private int modulus;
    194
    195    /**
    196     * Boolean flag to indicate the EOF has been reached. Once EOF has been reached, this Base64 object becomes useless,
    197     * and must be thrown away.
    198     */
    199    private boolean eof;
    200
    201    /**
    202     * Place holder for the 3 bytes we're dealing with for our base64 logic. Bitwise operations store and extract the
    203     * base64 encoding or decoding from this variable.
    204     */
    205    private int x;
    206
    207    /**
    208     * Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
    209     * <p>
    210     * When encoding the line length is 76, the line separator is CRLF, and the encoding table is STANDARD_ENCODE_TABLE.
    211     * </p>
    212     *
    213     * <p>
    214     * When decoding all variants are supported.
    215     * </p>
    216     */
    217    public Base64() {
    218        this(false);
    219    }
    220
    221    /**
    222     * Creates a Base64 codec used for decoding (all modes) and encoding in the given URL-safe mode.
    223     * <p>
    224     * When encoding the line length is 76, the line separator is CRLF, and the encoding table is STANDARD_ENCODE_TABLE.
    225     * </p>
    226     *
    227     * <p>
    228     * When decoding all variants are supported.
    229     * </p>
    230     *
    231     * @param urlSafe
    232     *            if <code>true</code>, URL-safe encoding is used. In most cases this should be set to
    233     *            <code>false</code>.
    234     * @since 1.4
    235     */
    236    public Base64(boolean urlSafe) {
    237        this(CHUNK_SIZE, CHUNK_SEPARATOR, urlSafe);
    238    }
    239
    240    /**
    241     * Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
    242     * <p>
    243     * When encoding the line length is given in the constructor, the line separator is CRLF, and the encoding table is
    244     * STANDARD_ENCODE_TABLE.
    245     * </p>
    246     * <p>
    247     * Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.
    248     * </p>
    249     * <p>
    250     * When decoding all variants are supported.
    251     * </p>
    252     *
    253     * @param lineLength
    254     *            Each line of encoded data will be at most of the given length (rounded down to nearest multiple of 4).
    255     *            If {@code lineLength <= 0}, then the output will not be divided into lines (chunks). Ignored when decoding.
    256     * @since 1.4
    257     */
    258    public Base64(int lineLength) {
    259        this(lineLength, CHUNK_SEPARATOR);
    260    }
    261
    262    /**
    263     * Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
    264     * <p>
    265     * When encoding the line length and line separator are given in the constructor, and the encoding table is
    266     * STANDARD_ENCODE_TABLE.
    267     * </p>
    268     * <p>
    269     * Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.
    270     * </p>
    271     * <p>
    272     * When decoding all variants are supported.
    273     * </p>
    274     *
    275     * @param lineLength
    276     *            Each line of encoded data will be at most of the given length (rounded down to nearest multiple of 4).
    277     *            If {@code lineLength <= 0}, then the output will not be divided into lines (chunks). Ignored when decoding.
    278     * @param lineSeparator
    279     *            Each line of encoded data will end with this sequence of bytes.
    280     * @throws IllegalArgumentException
    281     *             Thrown when the provided lineSeparator included some base64 characters.
    282     * @since 1.4
    283     */
    284    public Base64(int lineLength, byte[] lineSeparator) {
    285        this(lineLength, lineSeparator, false);
    286    }
    287
    288    /**
    289     * Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
    290     * <p>
    291     * When encoding the line length and line separator are given in the constructor, and the encoding table is
    292     * STANDARD_ENCODE_TABLE.
    293     * </p>
    294     * <p>
    295     * Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.
    296     * </p>
    297     * <p>
    298     * When decoding all variants are supported.
    299     * </p>
    300     *
    301     * @param lineLength
    302     *            Each line of encoded data will be at most of the given length (rounded down to nearest multiple of 4).
    303     *            If {@code lineLength <= 0}, then the output will not be divided into lines (chunks). Ignored when decoding.
    304     * @param lineSeparator
    305     *            Each line of encoded data will end with this sequence of bytes.
    306     * @param urlSafe
    307     *            Instead of emitting '+' and '/' we emit '-' and '_' respectively. urlSafe is only applied to encode
    308     *            operations. Decoding seamlessly handles both modes.
    309     * @throws IllegalArgumentException
    310     *             The provided lineSeparator included some base64 characters. That's not going to work!
    311     * @since 1.4
    312     */
    313    public Base64(int lineLength, byte[] lineSeparator, boolean urlSafe) {
    314        if (lineSeparator == null) {
    315            lineLength = 0;  // disable chunk-separating
    316            lineSeparator = EMPTY_BYTE_ARRAY;  // this just gets ignored
    317        }
    318        this.lineLength = lineLength > 0 ? (lineLength / 4) * 4 : 0;
    319        this.lineSeparator = new byte[lineSeparator.length];
    320        System.arraycopy(lineSeparator, 0, this.lineSeparator, 0, lineSeparator.length);
    321        if (lineLength > 0) {
    322            this.encodeSize = 4 + lineSeparator.length;
    323        } else {
    324            this.encodeSize = 4;
    325        }
    326        this.decodeSize = this.encodeSize - 1;
    327        if (containsBase64Byte(lineSeparator)) {
    328            String sep = newStringUtf8(lineSeparator);
    329            throw new IllegalArgumentException("lineSeperator must not contain base64 characters: [" + sep + "]");
    330        }
    331        this.encodeTable = urlSafe ? URL_SAFE_ENCODE_TABLE : STANDARD_ENCODE_TABLE;
    332    }
    333
    334    /**
    335     * Returns our current encode mode. True if we're URL-SAFE, false otherwise.
    336     *
    337     * @return true if we're in URL-SAFE mode, false otherwise.
    338     * @since 1.4
    339     */
    340    public boolean isUrlSafe() {
    341        return this.encodeTable == URL_SAFE_ENCODE_TABLE;
    342    }
    343
    344    /**
    345     * Returns true if this Base64 object has buffered data for reading.
    346     *
    347     * @return true if there is Base64 object still available for reading.
    348     */
    349    boolean hasData() {
    350        return this.buffer != null;
    351    }
    352
    353    /**
    354     * Returns the amount of buffered data available for reading.
    355     *
    356     * @return The amount of buffered data available for reading.
    357     */
    358    int avail() {
    359        return buffer != null ? pos - readPos : 0;
    360    }
    361
    362    /** Doubles our buffer. */
    363    private void resizeBuffer() {
    364        if (buffer == null) {
    365            buffer = new byte[DEFAULT_BUFFER_SIZE];
    366            pos = 0;
    367            readPos = 0;
    368        } else {
    369            byte[] b = new byte[buffer.length * DEFAULT_BUFFER_RESIZE_FACTOR];
    370            System.arraycopy(buffer, 0, b, 0, buffer.length);
    371            buffer = b;
    372        }
    373    }
    374
    375    /**
    376     * Extracts buffered data into the provided byte[] array, starting at position bPos, up to a maximum of bAvail
    377     * bytes. Returns how many bytes were actually extracted.
    378     *
    379     * @param b
    380     *            byte[] array to extract the buffered data into.
    381     * @param bPos
    382     *            position in byte[] array to start extraction at.
    383     * @param bAvail
    384     *            amount of bytes we're allowed to extract. We may extract fewer (if fewer are available).
    385     * @return The number of bytes successfully extracted into the provided byte[] array.
    386     */
    387    int readResults(byte[] b, int bPos, int bAvail) {
    388        if (buffer != null) {
    389            int len = Math.min(avail(), bAvail);
    390            if (buffer != b) {
    391                System.arraycopy(buffer, readPos, b, bPos, len);
    392                readPos += len;
    393                if (readPos >= pos) {
    394                    buffer = null;
    395                }
    396            } else {
    397                // Re-using the original consumer's output array is only
    398                // allowed for one round.
    399                buffer = null;
    400            }
    401            return len;
    402        }
    403        return eof ? -1 : 0;
    404    }
    405
    406    /**
    407     * Sets the streaming buffer. This is a small optimization where we try to buffer directly to the consumer's output
    408     * array for one round (if the consumer calls this method first) instead of starting our own buffer.
    409     *
    410     * @param out
    411     *            byte[] array to buffer directly to.
    412     * @param outPos
    413     *            Position to start buffering into.
    414     * @param outAvail
    415     *            Amount of bytes available for direct buffering.
    416     */
    417    void setInitialBuffer(byte[] out, int outPos, int outAvail) {
    418        // We can re-use consumer's original output array under
    419        // special circumstances, saving on some System.arraycopy().
    420        if (out != null && out.length == outAvail) {
    421            buffer = out;
    422            pos = outPos;
    423            readPos = outPos;
    424        }
    425    }
    426
    427    /**
    428     * <p>
    429     * Encodes all of the provided data, starting at inPos, for inAvail bytes. Must be called at least twice: once with
    430     * the data to encode, and once with inAvail set to "-1" to alert encoder that EOF has been reached, so flush last
    431     * remaining bytes (if not multiple of 3).
    432     * </p>
    433     * <p>
    434     * Thanks to "commons" project in ws.apache.org for the bitwise operations, and general approach.
    435     * http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
    436     * </p>
    437     *
    438     * @param in
    439     *            byte[] array of binary data to base64 encode.
    440     * @param inPos
    441     *            Position to start reading data from.
    442     * @param inAvail
    443     *            Amount of bytes available from input for encoding.
    444     */
    445    void encode(byte[] in, int inPos, int inAvail) {
    446        if (eof) {
    447            return;
    448        }
    449        // inAvail < 0 is how we're informed of EOF in the underlying data we're
    450        // encoding.
    451        if (inAvail < 0) {
    452            eof = true;
    453            if (buffer == null || buffer.length - pos < encodeSize) {
    454                resizeBuffer();
    455            }
    456            switch (modulus) {
    457                case 1 :
    458                    buffer[pos++] = encodeTable[(x >> 2) & MASK_6BITS];
    459                    buffer[pos++] = encodeTable[(x << 4) & MASK_6BITS];
    460                    // URL-SAFE skips the padding to further reduce size.
    461                    if (encodeTable == STANDARD_ENCODE_TABLE) {
    462                        buffer[pos++] = PAD;
    463                        buffer[pos++] = PAD;
    464                    }
    465                    break;
    466
    467                case 2 :
    468                    buffer[pos++] = encodeTable[(x >> 10) & MASK_6BITS];
    469                    buffer[pos++] = encodeTable[(x >> 4) & MASK_6BITS];
    470                    buffer[pos++] = encodeTable[(x << 2) & MASK_6BITS];
    471                    // URL-SAFE skips the padding to further reduce size.
    472                    if (encodeTable == STANDARD_ENCODE_TABLE) {
    473                        buffer[pos++] = PAD;
    474                    }
    475                    break;
    476                default:
    477                    break;  // other values ignored
    478            }
    479            if (lineLength > 0 && pos > 0) {
    480                System.arraycopy(lineSeparator, 0, buffer, pos, lineSeparator.length);
    481                pos += lineSeparator.length;
    482            }
    483        } else {
    484            for (int i = 0; i < inAvail; i++) {
    485                if (buffer == null || buffer.length - pos < encodeSize) {
    486                    resizeBuffer();
    487                }
    488                modulus = (++modulus) % 3;
    489                int b = in[inPos++];
    490                if (b < 0) {
    491                    b += 256;
    492                }
    493                x = (x << 8) + b;
    494                if (0 == modulus) {
    495                    buffer[pos++] = encodeTable[(x >> 18) & MASK_6BITS];
    496                    buffer[pos++] = encodeTable[(x >> 12) & MASK_6BITS];
    497                    buffer[pos++] = encodeTable[(x >> 6) & MASK_6BITS];
    498                    buffer[pos++] = encodeTable[x & MASK_6BITS];
    499                    currentLinePos += 4;
    500                    if (lineLength > 0 && lineLength <= currentLinePos) {
    501                        System.arraycopy(lineSeparator, 0, buffer, pos, lineSeparator.length);
    502                        pos += lineSeparator.length;
    503                        currentLinePos = 0;
    504                    }
    505                }
    506            }
    507        }
    508    }
    509
    510    /**
    511     * <p>
    512     * Decodes all of the provided data, starting at inPos, for inAvail bytes. Should be called at least twice: once
    513     * with the data to decode, and once with inAvail set to "-1" to alert decoder that EOF has been reached. The "-1"
    514     * call is not necessary when decoding, but it doesn't hurt, either.
    515     * </p>
    516     * <p>
    517     * Ignores all non-base64 characters. This is how chunked (e.g. 76 character) data is handled, since CR and LF are
    518     * silently ignored, but has implications for other bytes, too. This method subscribes to the garbage-in,
    519     * garbage-out philosophy: it will not check the provided data for validity.
    520     * </p>
    521     * <p>
    522     * Thanks to "commons" project in ws.apache.org for the bitwise operations, and general approach.
    523     * http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
    524     * </p>
    525     *
    526     * @param in
    527     *            byte[] array of ascii data to base64 decode.
    528     * @param inPos
    529     *            Position to start reading data from.
    530     * @param inAvail
    531     *            Amount of bytes available from input for encoding.
    532     */
    533    void decode(byte[] in, int inPos, int inAvail) {
    534        if (eof) {
    535            return;
    536        }
    537        if (inAvail < 0) {
    538            eof = true;
    539        }
    540        for (int i = 0; i < inAvail; i++) {
    541            if (buffer == null || buffer.length - pos < decodeSize) {
    542                resizeBuffer();
    543            }
    544            byte b = in[inPos++];
    545            if (b == PAD) {
    546                // We're done.
    547                eof = true;
    548                break;
    549            } else {
    550                if (b >= 0 && b < DECODE_TABLE.length) {
    551                    int result = DECODE_TABLE[b];
    552                    if (result >= 0) {
    553                        modulus = (++modulus) % 4;
    554                        x = (x << 6) + result;
    555                        if (modulus == 0) {
    556                            buffer[pos++] = (byte) ((x >> 16) & MASK_8BITS);
    557                            buffer[pos++] = (byte) ((x >> 8) & MASK_8BITS);
    558                            buffer[pos++] = (byte) (x & MASK_8BITS);
    559                        }
    560                    }
    561                }
    562            }
    563        }
    564
    565        // Two forms of EOF as far as base64 decoder is concerned: actual
    566        // EOF (-1) and first time '=' character is encountered in stream.
    567        // This approach makes the '=' padding characters completely optional.
    568        if (eof && modulus != 0) {
    569            x = x << 6;
    570            switch (modulus) {
    571                case 2 :
    572                    x = x << 6;
    573                    buffer[pos++] = (byte) ((x >> 16) & MASK_8BITS);
    574                    break;
    575                case 3 :
    576                    buffer[pos++] = (byte) ((x >> 16) & MASK_8BITS);
    577                    buffer[pos++] = (byte) ((x >> 8) & MASK_8BITS);
    578                    break;
    579                default:
    580                    break;  // other values ignored
    581            }
    582        }
    583    }
    584
    585    /**
    586     * Returns whether or not the <code>octet</code> is in the base 64 alphabet.
    587     *
    588     * @param octet
    589     *            The value to test
    590     * @return <code>true</code> if the value is defined in the the base 64 alphabet, <code>false</code> otherwise.
    591     * @since 1.4
    592     */
    593    public static boolean isBase64(byte octet) {
    594        return octet == PAD || (octet >= 0 && octet < DECODE_TABLE.length && DECODE_TABLE[octet] != -1);
    595    }
    596
    597    /**
    598     * Tests a given byte array to see if it contains only valid characters within the Base64 alphabet. Currently the
    599     * method treats whitespace as valid.
    600     *
    601     * @param arrayOctet
    602     *            byte array to test
    603     * @return <code>true</code> if all bytes are valid characters in the Base64 alphabet or if the byte array is empty;
    604     *         false, otherwise
    605     */
    606    public static boolean isArrayByteBase64(byte[] arrayOctet) {
    607        for (int i = 0; i < arrayOctet.length; i++) {
    608            if (!isBase64(arrayOctet[i]) && !isWhiteSpace(arrayOctet[i])) {
    609                return false;
    610            }
    611        }
    612        return true;
    613    }
    614
    615    /**
    616     * Tests a given byte array to see if it contains only valid characters within the Base64 alphabet.
    617     *
    618     * @param arrayOctet
    619     *            byte array to test
    620     * @return <code>true</code> if any byte is a valid character in the Base64 alphabet; false herwise
    621     */
    622    private static boolean containsBase64Byte(byte[] arrayOctet) {
    623        for (byte element : arrayOctet)
    624        {
    625            if (isBase64(element)) {
    626                return true;
    627            }
    628        }
    629        return false;
    630    }
    631
    632    /**
    633     * Encodes binary data using the base64 algorithm but does not chunk the output.
    634     *
    635     * @param binaryData
    636     *            binary data to encode
    637     * @return byte[] containing Base64 characters in their UTF-8 representation.
    638     */
    639    public static byte[] encodeBase64(byte[] binaryData) {
    640        return encodeBase64(binaryData, false);
    641    }
    642
    643    /**
    644     * Encodes binary data using the base64 algorithm into 76 character blocks separated by CRLF.
    645     * <p>
    646     * For a non-chunking version, see {@link #encodeBase64StringUnChunked(byte[])}.
    647     *
    648     * @param binaryData
    649     *            binary data to encode
    650     * @return String containing Base64 characters.
    651     * @since 1.4
    652     */
    653    public static String encodeBase64String(byte[] binaryData) {
    654        return newStringUtf8(encodeBase64(binaryData, true));
    655    }
    656
    657    /**
    658     * Encodes binary data using the base64 algorithm, without using chunking.
    659     * <p>
    660     * For a chunking version, see {@link #encodeBase64String(byte[])}.
    661     *
    662     * @param binaryData
    663     *            binary data to encode
    664     * @return String containing Base64 characters.
    665     * @since 3.2
    666     */
    667    public static String encodeBase64StringUnChunked(byte[] binaryData) {
    668        return newStringUtf8(encodeBase64(binaryData, false));
    669    }
    670
    671    /**
    672     * Encodes binary data using the base64 algorithm.
    673     *
    674     * @param binaryData
    675     *            binary data to encode
    676     * @param useChunking whether to split the output into chunks
    677     * @return String containing Base64 characters.
    678     * @since 3.2
    679     */
    680    public static String encodeBase64String(byte[] binaryData, boolean useChunking) {
    681        return newStringUtf8(encodeBase64(binaryData, useChunking));
    682    }
    683
    684    /**
    685     * Encodes binary data using a URL-safe variation of the base64 algorithm but does not chunk the output. The
    686     * url-safe variation emits - and _ instead of + and / characters.
    687     *
    688     * @param binaryData
    689     *            binary data to encode
    690     * @return byte[] containing Base64 characters in their UTF-8 representation.
    691     * @since 1.4
    692     */
    693    public static byte[] encodeBase64URLSafe(byte[] binaryData) {
    694        return encodeBase64(binaryData, false, true);
    695    }
    696
    697    /**
    698     * Encodes binary data using a URL-safe variation of the base64 algorithm but does not chunk the output. The
    699     * url-safe variation emits - and _ instead of + and / characters.
    700     *
    701     * @param binaryData
    702     *            binary data to encode
    703     * @return String containing Base64 characters
    704     * @since 1.4
    705     */
    706    public static String encodeBase64URLSafeString(byte[] binaryData) {
    707        return newStringUtf8(encodeBase64(binaryData, false, true));
    708    }
    709
    710    /**
    711     * Encodes binary data using the base64 algorithm and chunks the encoded output into 76 character blocks
    712     *
    713     * @param binaryData
    714     *            binary data to encode
    715     * @return Base64 characters chunked in 76 character blocks
    716     */
    717    public static byte[] encodeBase64Chunked(byte[] binaryData) {
    718        return encodeBase64(binaryData, true);
    719    }
    720
    721    /**
    722     * Decodes a String containing containing characters in the Base64 alphabet.
    723     *
    724     * @param pArray
    725     *            A String containing Base64 character data
    726     * @return a byte array containing binary data
    727     * @since 1.4
    728     */
    729    public byte[] decode(String pArray) {
    730        return decode(getBytesUtf8(pArray));
    731    }
    732
    733    private byte[] getBytesUtf8(String pArray) {
    734        try {
    735            return pArray.getBytes("UTF8");
    736        } catch (UnsupportedEncodingException e) {
    737            throw new RuntimeException(e);
    738        }
    739    }
    740
    741    /**
    742     * Decodes a byte[] containing containing characters in the Base64 alphabet.
    743     *
    744     * @param pArray
    745     *            A byte array containing Base64 character data
    746     * @return a byte array containing binary data
    747     */
    748    public byte[] decode(byte[] pArray) {
    749        reset();
    750        if (pArray == null || pArray.length == 0) {
    751            return pArray;
    752        }
    753        long len = (pArray.length * 3) / 4;
    754        byte[] buf = new byte[(int) len];
    755        setInitialBuffer(buf, 0, buf.length);
    756        decode(pArray, 0, pArray.length);
    757        decode(pArray, 0, -1); // Notify decoder of EOF.
    758
    759        // Would be nice to just return buf (like we sometimes do in the encode
    760        // logic), but we have no idea what the line-length was (could even be
    761        // variable).  So we cannot determine ahead of time exactly how big an
    762        // array is necessary.  Hence the need to construct a 2nd byte array to
    763        // hold the final result:
    764
    765        byte[] result = new byte[pos];
    766        readResults(result, 0, result.length);
    767        return result;
    768    }
    769
    770    /**
    771     * Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
    772     *
    773     * @param binaryData
    774     *            Array containing binary data to encode.
    775     * @param isChunked
    776     *            if <code>true</code> this encoder will chunk the base64 output into 76 character blocks
    777     * @return Base64-encoded data.
    778     * @throws IllegalArgumentException
    779     *             Thrown when the input array needs an output array bigger than {@link Integer#MAX_VALUE}
    780     */
    781    public static byte[] encodeBase64(byte[] binaryData, boolean isChunked) {
    782        return encodeBase64(binaryData, isChunked, false);
    783    }
    784
    785    /**
    786     * Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
    787     *
    788     * @param binaryData
    789     *            Array containing binary data to encode.
    790     * @param isChunked
    791     *            if <code>true</code> this encoder will chunk the base64 output into 76 character blocks
    792     * @param urlSafe
    793     *            if <code>true</code> this encoder will emit - and _ instead of the usual + and / characters.
    794     * @return Base64-encoded data.
    795     * @throws IllegalArgumentException
    796     *             Thrown when the input array needs an output array bigger than {@link Integer#MAX_VALUE}
    797     * @since 1.4
    798     */
    799    public static byte[] encodeBase64(byte[] binaryData, boolean isChunked, boolean urlSafe) {
    800        return encodeBase64(binaryData, isChunked, urlSafe, Integer.MAX_VALUE);
    801    }
    802
    803    /**
    804     * Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
    805     *
    806     * @param binaryData
    807     *            Array containing binary data to encode.
    808     * @param isChunked
    809     *            if <code>true</code> this encoder will chunk the base64 output into 76 character blocks
    810     * @param urlSafe
    811     *            if <code>true</code> this encoder will emit - and _ instead of the usual + and / characters.
    812     * @param maxResultSize
    813     *            The maximum result size to accept.
    814     * @return Base64-encoded data.
    815     * @throws IllegalArgumentException
    816     *             Thrown when the input array needs an output array bigger than maxResultSize
    817     * @since 1.4
    818     */
    819    public static byte[] encodeBase64(byte[] binaryData, boolean isChunked, boolean urlSafe, int maxResultSize) {
    820        if (binaryData == null || binaryData.length == 0) {
    821            return binaryData;
    822        }
    823
    824        long len = getEncodeLength(binaryData, isChunked ? CHUNK_SIZE : 0, isChunked ? CHUNK_SEPARATOR : EMPTY_BYTE_ARRAY);
    825        if (len > maxResultSize) {
    826            throw new IllegalArgumentException("Input array too big, the output array would be bigger (" +
    827                len +
    828                ") than the specified maxium size of " +
    829                maxResultSize);
    830        }
    831
    832        Base64 b64 = isChunked ? new Base64(urlSafe) : new Base64(0, CHUNK_SEPARATOR, urlSafe);
    833        return b64.encode(binaryData);
    834    }
    835
    836    /**
    837     * Decodes a Base64 String into octets
    838     *
    839     * @param base64String
    840     *            String containing Base64 data
    841     * @return Array containing decoded data.
    842     * @since 1.4
    843     */
    844    public static byte[] decodeBase64(String base64String) {
    845        return new Base64().decode(base64String);
    846    }
    847
    848    /**
    849     * Decodes Base64 data into octets
    850     *
    851     * @param base64Data
    852     *            Byte array containing Base64 data
    853     * @return Array containing decoded data.
    854     */
    855    public static byte[] decodeBase64(byte[] base64Data) {
    856        return new Base64().decode(base64Data);
    857    }
    858
    859
    860
    861    /**
    862     * Checks if a byte value is whitespace or not.
    863     *
    864     * @param byteToCheck
    865     *            the byte to check
    866     * @return true if byte is whitespace, false otherwise
    867     */
    868    private static boolean isWhiteSpace(byte byteToCheck) {
    869        switch (byteToCheck) {
    870            case ' ' :
    871            case '\n' :
    872            case '\r' :
    873            case '\t' :
    874                return true;
    875            default :
    876                return false;
    877        }
    878    }
    879
    880    /**
    881     * Encodes a byte[] containing binary data, into a String containing characters in the Base64 alphabet.
    882     *
    883     * @param pArray
    884     *            a byte array containing binary data
    885     * @return A String containing only Base64 character data
    886     * @since 1.4
    887     */
    888    public String encodeToString(byte[] pArray) {
    889        return newStringUtf8(encode(pArray));
    890    }
    891
    892    private static String newStringUtf8(byte[] encode) {
    893        String str = null;
    894        try {
    895            str = new String(encode, "UTF8");
    896        } catch (UnsupportedEncodingException ue) {
    897            throw new RuntimeException(ue);
    898        }
    899        return str;
    900    }
    901
    902    /**
    903     * Encodes a byte[] containing binary data, into a byte[] containing characters in the Base64 alphabet.
    904     *
    905     * @param pArray
    906     *            a byte array containing binary data
    907     * @return A byte array containing only Base64 character data
    908     */
    909    public byte[] encode(byte[] pArray) {
    910        reset();
    911        if (pArray == null || pArray.length == 0) {
    912            return pArray;
    913        }
    914        long len = getEncodeLength(pArray, lineLength, lineSeparator);
    915        byte[] buf = new byte[(int) len];
    916        setInitialBuffer(buf, 0, buf.length);
    917        encode(pArray, 0, pArray.length);
    918        encode(pArray, 0, -1); // Notify encoder of EOF.
    919        // Encoder might have resized, even though it was unnecessary.
    920        if (buffer != buf) {
    921            readResults(buf, 0, buf.length);
    922        }
    923        // In URL-SAFE mode we skip the padding characters, so sometimes our
    924        // final length is a bit smaller.
    925        if (isUrlSafe() && pos < buf.length) {
    926            byte[] smallerBuf = new byte[pos];
    927            System.arraycopy(buf, 0, smallerBuf, 0, pos);
    928            buf = smallerBuf;
    929        }
    930        return buf;
    931    }
    932
    933    /**
    934     * Pre-calculates the amount of space needed to base64-encode the supplied array.
    935     *
    936     * @param pArray byte[] array which will later be encoded
    937     * @param chunkSize line-length of the output (<= 0 means no chunking) between each
    938     *        chunkSeparator (e.g. CRLF).
    939     * @param chunkSeparator the sequence of bytes used to separate chunks of output (e.g. CRLF).
    940     *
    941     * @return amount of space needed to encoded the supplied array.  Returns
    942     *         a long since a max-len array will require Integer.MAX_VALUE + 33%.
    943     */
    944    private static long getEncodeLength(byte[] pArray, int chunkSize, byte[] chunkSeparator) {
    945        // base64 always encodes to multiples of 4.
    946        chunkSize = (chunkSize / 4) * 4;
    947
    948        long len = (pArray.length * 4) / 3;
    949        long mod = len % 4;
    950        if (mod != 0) {
    951            len += 4 - mod;
    952        }
    953        if (chunkSize > 0) {
    954            boolean lenChunksPerfectly = len % chunkSize == 0;
    955            len += (len / chunkSize) * chunkSeparator.length;
    956            if (!lenChunksPerfectly) {
    957                len += chunkSeparator.length;
    958            }
    959        }
    960        return len;
    961    }
    962
    963    // Implementation of integer encoding used for crypto
    964    /**
    965     * Decodes a byte64-encoded integer according to crypto standards such as W3C's XML-Signature
    966     *
    967     * @param pArray
    968     *            a byte array containing base64 character data
    969     * @return A BigInteger
    970     * @since 1.4
    971     */
    972    public static BigInteger decodeInteger(byte[] pArray) {
    973        return new BigInteger(1, decodeBase64(pArray));
    974    }
    975
    976    /**
    977     * Encodes to a byte64-encoded integer according to crypto standards such as W3C's XML-Signature
    978     *
    979     * @param bigInt
    980     *            a BigInteger
    981     * @return A byte array containing base64 character data
    982     * @throws NullPointerException
    983     *             if null is passed in
    984     * @since 1.4
    985     */
    986    public static byte[] encodeInteger(BigInteger bigInt) {
    987        if (bigInt == null) {
    988            throw new NullPointerException("encodeInteger called with null parameter");
    989        }
    990        return encodeBase64(toIntegerBytes(bigInt), false);
    991    }
    992
    993    /**
    994     * Returns a byte-array representation of a <code>BigInteger</code> without sign bit.
    995     *
    996     * @param bigInt
    997     *            <code>BigInteger</code> to be converted
    998     * @return a byte array representation of the BigInteger parameter
    999     */
    1000    static byte[] toIntegerBytes(BigInteger bigInt) {
    1001        int bitlen = bigInt.bitLength();
    1002        // round bitlen
    1003        bitlen = ((bitlen + 7) >> 3) << 3;
    1004        byte[] bigBytes = bigInt.toByteArray();
    1005
    1006        if (((bigInt.bitLength() % 8) != 0) && (((bigInt.bitLength() / 8) + 1) == (bitlen / 8))) {
    1007            return bigBytes;
    1008        }
    1009        // set up params for copying everything but sign bit
    1010        int startSrc = 0;
    1011        int len = bigBytes.length;
    1012
    1013        // if bigInt is exactly byte-aligned, just skip signbit in copy
    1014        if ((bigInt.bitLength() % 8) == 0) {
    1015            startSrc = 1;
    1016            len--;
    1017        }
    1018        int startDst = bitlen / 8 - len; // to pad w/ nulls as per spec
    1019        byte[] resizedBytes = new byte[bitlen / 8];
    1020        System.arraycopy(bigBytes, startSrc, resizedBytes, startDst, len);
    1021        return resizedBytes;
    1022    }
    1023
    1024    /**
    1025     * Resets this Base64 object to its initial newly constructed state.
    1026     */
    1027    private void reset() {
    1028        buffer = null;
    1029        pos = 0;
    1030        readPos = 0;
    1031        currentLinePos = 0;
    1032        modulus = 0;
    1033        eof = false;
    1034    }
    1035
    1036    // Getters for use in testing
    1037
    1038    int getLineLength() {
    1039        return lineLength;
    1040    }
    1041
    1042    byte[] getLineSeparator() {
    1043        return lineSeparator.clone();
    1044    }
    1045}