/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You under the Apache License, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License.  You may obtain a copy of the License at
    *
    *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package org.apache.commons.codec.binary;
  
  import java.math.BigInteger;
  
  /**
   * Provides Base64 encoding and decoding as defined by <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>.
   *
   * <p>
   * This class implements section <cite>6.8. Base64 Content-Transfer-Encoding</cite> from RFC 2045 <cite>Multipurpose
   * Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies</cite> by Freed and Borenstein.
   * </p>
   * <p>
   * The class can be parameterized in the following manner with various constructors:
   * </p>
   * <ul>
   * <li>URL-safe mode: Default off.</li>
   * <li>Line length: Default 76. Line length that aren't multiples of 4 will still essentially end up being multiples of
   * 4 in the encoded data.
   * <li>Line separator: Default is CRLF ("\r\n")</li>
   * </ul>
   * <p>
   * The URL-safe parameter is only applied to encode operations. Decoding seamlessly handles both modes.
   * </p>
   * <p>
   * Since this class operates directly on byte streams, and not character streams, it is hard-coded to only
   * encode/decode character encodings which are compatible with the lower 127 ASCII chart (ISO-8859-1, Windows-1252,
   * UTF-8, etc).
   * </p>
   * <p>
   * This class is thread-safe.
   * </p>
   *
   * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>
   * @since 1.0
   * @version $Id: Base64.java 1789158 2017-03-28 15:04:58Z sebb $
   */
  public class Base64 extends BaseNCodec {
  
      /**
       * BASE32 characters are 6 bits in length.
       * They are formed by taking a block of 3 octets to form a 24-bit string,
       * which is converted into 4 BASE64 characters.
       */
      private static final int BITS_PER_ENCODED_BYTE = 6;
      private static final int BYTES_PER_UNENCODED_BLOCK = 3;
      private static final int BYTES_PER_ENCODED_BLOCK = 4;
  
      /**
       * Chunk separator per RFC 2045 section 2.1.
       *
       * <p>
       * N.B. The next major release may break compatibility and make this field private.
       * </p>
       *
       * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 2.1</a>
       */
      static final byte[] CHUNK_SEPARATOR = {'\r', '\n'};
  
      /**
       * This array is a lookup table that translates 6-bit positive integer index values into their "Base64 Alphabet"
       * equivalents as specified in Table 1 of RFC 2045.
       *
       * Thanks to "commons" project in ws.apache.org for this code.
       * http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
       */
      private static final byte[] STANDARD_ENCODE_TABLE = {
              'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
              'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
              'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
              'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
              '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'
      };
  
      /**
       * This is a copy of the STANDARD_ENCODE_TABLE above, but with + and /
       * changed to - and _ to make the encoded Base64 results more URL-SAFE.
       * This table is only used when the Base64's mode is set to URL-SAFE.
       */
      private static final byte[] URL_SAFE_ENCODE_TABLE = {
              'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
              'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
              'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
             'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
             '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-', '_'
     };
 
     /**
      * This array is a lookup table that translates Unicode characters drawn from the "Base64 Alphabet" (as specified
      * in Table 1 of RFC 2045) into their 6-bit positive integer equivalents. Characters that are not in the Base64
      * alphabet but fall within the bounds of the array are translated to -1.
      *
      * Note: '+' and '-' both decode to 62. '/' and '_' both decode to 63. This means decoder seamlessly handles both
      * URL_SAFE and STANDARD base64. (The encoder, on the other hand, needs to know ahead of time what to emit).
      *
      * Thanks to "commons" project in ws.apache.org for this code.
      * http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
      */
     private static final byte[] DECODE_TABLE = {
         //   0   1   2   3   4   5   6   7   8   9   A   B   C   D   E   F
             -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 00-0f
             -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 10-1f
             -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, 62, -1, 63, // 20-2f + - /
             52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, // 30-3f 0-9
             -1,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, // 40-4f A-O
             15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, 63, // 50-5f P-Z _
             -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, // 60-6f a-o
             41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51                      // 70-7a p-z
     };
 
     /**
      * Base64 uses 6-bit fields.
      */
     /** Mask used to extract 6 bits, used when encoding */
     private static final int MASK_6BITS = 0x3f;
 
     // The static final fields above are used for the original static byte[] methods on Base64.
     // The private member fields below are used with the new streaming approach, which requires
     // some state be preserved between calls of encode() and decode().
 
     /**
      * Encode table to use: either STANDARD or URL_SAFE. Note: the DECODE_TABLE above remains static because it is able
      * to decode both STANDARD and URL_SAFE streams, but the encodeTable must be a member variable so we can switch
      * between the two modes.
      */
     private final byte[] encodeTable;
 
     // Only one decode table currently; keep for consistency with Base32 code
     private final byte[] decodeTable = DECODE_TABLE;
 
     /**
      * Line separator for encoding. Not used when decoding. Only used if lineLength &gt; 0.
      */
     private final byte[] lineSeparator;
 
     /**
      * Convenience variable to help us determine when our buffer is going to run out of room and needs resizing.
      * <code>decodeSize = 3 + lineSeparator.length;</code>
      */
     private final int decodeSize;
 
     /**
      * Convenience variable to help us determine when our buffer is going to run out of room and needs resizing.
      * <code>encodeSize = 4 + lineSeparator.length;</code>
      */
     private final int encodeSize;
 
     /**
      * Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
      * <p>
      * When encoding the line length is 0 (no chunking), and the encoding table is STANDARD_ENCODE_TABLE.
      * </p>
      *
      * <p>
      * When decoding all variants are supported.
      * </p>
      */
     public Base64() {
         this(0);
     }
 
     /**
      * Creates a Base64 codec used for decoding (all modes) and encoding in the given URL-safe mode.
      * <p>
      * When encoding the line length is 76, the line separator is CRLF, and the encoding table is STANDARD_ENCODE_TABLE.
      * </p>
      *
      * <p>
      * When decoding all variants are supported.
      * </p>
      *
      * @param urlSafe
      *            if <code>true</code>, URL-safe encoding is used. In most cases this should be set to
      *            <code>false</code>.
      * @since 1.4
      */
     public Base64(final boolean urlSafe) {
         this(MIME_CHUNK_SIZE, CHUNK_SEPARATOR, urlSafe);
     }
 
     /**
      * Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
      * <p>
      * When encoding the line length is given in the constructor, the line separator is CRLF, and the encoding table is
      * STANDARD_ENCODE_TABLE.
      * </p>
      * <p>
      * Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.
      * </p>
      * <p>
      * When decoding all variants are supported.
      * </p>
      *
      * @param lineLength
      *            Each line of encoded data will be at most of the given length (rounded down to nearest multiple of
      *            4). If lineLength &lt;= 0, then the output will not be divided into lines (chunks). Ignored when
      *            decoding.
      * @since 1.4
      */
     public Base64(final int lineLength) {
         this(lineLength, CHUNK_SEPARATOR);
     }
 
     /**
      * Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
      * <p>
      * When encoding the line length and line separator are given in the constructor, and the encoding table is
      * STANDARD_ENCODE_TABLE.
      * </p>
      * <p>
      * Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.
      * </p>
      * <p>
      * When decoding all variants are supported.
      * </p>
      *
      * @param lineLength
      *            Each line of encoded data will be at most of the given length (rounded down to nearest multiple of
      *            4). If lineLength &lt;= 0, then the output will not be divided into lines (chunks). Ignored when
      *            decoding.
      * @param lineSeparator
      *            Each line of encoded data will end with this sequence of bytes.
      * @throws IllegalArgumentException
      *             Thrown when the provided lineSeparator included some base64 characters.
      * @since 1.4
      */
     public Base64(final int lineLength, final byte[] lineSeparator) {
         this(lineLength, lineSeparator, false);
     }
 
     /**
      * Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
      * <p>
      * When encoding the line length and line separator are given in the constructor, and the encoding table is
      * STANDARD_ENCODE_TABLE.
      * </p>
      * <p>
      * Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.
      * </p>
      * <p>
      * When decoding all variants are supported.
      * </p>
      *
      * @param lineLength
      *            Each line of encoded data will be at most of the given length (rounded down to nearest multiple of
      *            4). If lineLength &lt;= 0, then the output will not be divided into lines (chunks). Ignored when
      *            decoding.
      * @param lineSeparator
      *            Each line of encoded data will end with this sequence of bytes.
      * @param urlSafe
      *            Instead of emitting '+' and '/' we emit '-' and '_' respectively. urlSafe is only applied to encode
      *            operations. Decoding seamlessly handles both modes.
      *            <b>Note: no padding is added when using the URL-safe alphabet.</b>
      * @throws IllegalArgumentException
      *             The provided lineSeparator included some base64 characters. That's not going to work!
      * @since 1.4
      */
     public Base64(final int lineLength, final byte[] lineSeparator, final boolean urlSafe) {
         super(BYTES_PER_UNENCODED_BLOCK, BYTES_PER_ENCODED_BLOCK,
                 lineLength,
                 lineSeparator == null ? 0 : lineSeparator.length);
         // TODO could be simplified if there is no requirement to reject invalid line sep when length <=0
         // @see test case Base64Test.testConstructors()
         if (lineSeparator != null) {
             if (containsAlphabetOrPad(lineSeparator)) {
                 final String sep = StringUtils.newStringUtf8(lineSeparator);
                 throw new IllegalArgumentException("lineSeparator must not contain base64 characters: [" + sep + "]");
             }
             if (lineLength > 0){ // null line-sep forces no chunking rather than throwing IAE
                 this.encodeSize = BYTES_PER_ENCODED_BLOCK + lineSeparator.length;
                 this.lineSeparator = new byte[lineSeparator.length];
                 System.arraycopy(lineSeparator, 0, this.lineSeparator, 0, lineSeparator.length);
             } else {
                 this.encodeSize = BYTES_PER_ENCODED_BLOCK;
                 this.lineSeparator = null;
             }
         } else {
             this.encodeSize = BYTES_PER_ENCODED_BLOCK;
             this.lineSeparator = null;
         }
         this.decodeSize = this.encodeSize - 1;
         this.encodeTable = urlSafe ? URL_SAFE_ENCODE_TABLE : STANDARD_ENCODE_TABLE;
     }
 
     /**
      * Returns our current encode mode. True if we're URL-SAFE, false otherwise.
      *
      * @return true if we're in URL-SAFE mode, false otherwise.
      * @since 1.4
      */
     public boolean isUrlSafe() {
         return this.encodeTable == URL_SAFE_ENCODE_TABLE;
     }
 
     /**
      * <p>
      * 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 inAvail set to "-1" to alert encoder that EOF has been reached, to flush last
      * remaining bytes (if not multiple of 3).
      * </p>
      * <p><b>Note: no padding is added when encoding using the URL-safe alphabet.</b></p>
      * <p>
      * Thanks to "commons" project in ws.apache.org for the bitwise operations, and general approach.
      * http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
      * </p>
      *
      * @param in
      *            byte[] array of binary data to base64 encode.
      * @param inPos
      *            Position to start reading data from.
      * @param inAvail
      *            Amount of bytes available from input for encoding.
      * @param context
      *            the context to be used
      */
     @Override
     void encode(final byte[] in, int inPos, final int inAvail, final Context context) {
         if (context.eof) {
             return;
         }
         // inAvail < 0 is how we're informed of EOF in the underlying data we're
         // encoding.
         if (inAvail < 0) {
             context.eof = true;
             if (0 == context.modulus && lineLength == 0) {
                 return; // no leftovers to process and not using chunking
             }
             final byte[] buffer = ensureBufferSize(encodeSize, context);
             final int savedPos = context.pos;
             switch (context.modulus) { // 0-2
                 case 0 : // nothing to do here
                     break;
                 case 1 : // 8 bits = 6 + 2
                     // top 6 bits:
                     buffer[context.pos++] = encodeTable[(context.ibitWorkArea >> 2) & MASK_6BITS];
                     // remaining 2:
                     buffer[context.pos++] = encodeTable[(context.ibitWorkArea << 4) & MASK_6BITS];
                     // URL-SAFE skips the padding to further reduce size.
                     if (encodeTable == STANDARD_ENCODE_TABLE) {
                         buffer[context.pos++] = pad;
                         buffer[context.pos++] = pad;
                     }
                     break;
 
                 case 2 : // 16 bits = 6 + 6 + 4
                     buffer[context.pos++] = encodeTable[(context.ibitWorkArea >> 10) & MASK_6BITS];
                     buffer[context.pos++] = encodeTable[(context.ibitWorkArea >> 4) & MASK_6BITS];
                     buffer[context.pos++] = encodeTable[(context.ibitWorkArea << 2) & MASK_6BITS];
                     // URL-SAFE skips the padding to further reduce size.
                     if (encodeTable == STANDARD_ENCODE_TABLE) {
                         buffer[context.pos++] = pad;
                     }
                     break;
                 default:
                     throw new IllegalStateException("Impossible modulus "+context.modulus);
             }
             context.currentLinePos += context.pos - savedPos; // keep track of current line position
             // if currentPos == 0 we are at the start of a line, so don't add CRLF
             if (lineLength > 0 && context.currentLinePos > 0) {
                 System.arraycopy(lineSeparator, 0, buffer, context.pos, lineSeparator.length);
                 context.pos += lineSeparator.length;
             }
         } else {
             for (int i = 0; i < inAvail; i++) {
                 final byte[] buffer = ensureBufferSize(encodeSize, context);
                 context.modulus = (context.modulus+1) % BYTES_PER_UNENCODED_BLOCK;
                 int b = in[inPos++];
                 if (b < 0) {
                     b += 256;
                 }
                 context.ibitWorkArea = (context.ibitWorkArea << 8) + b; //  BITS_PER_BYTE
                 if (0 == context.modulus) { // 3 bytes = 24 bits = 4 * 6 bits to extract
                     buffer[context.pos++] = encodeTable[(context.ibitWorkArea >> 18) & MASK_6BITS];
                     buffer[context.pos++] = encodeTable[(context.ibitWorkArea >> 12) & MASK_6BITS];
                     buffer[context.pos++] = encodeTable[(context.ibitWorkArea >> 6) & MASK_6BITS];
                     buffer[context.pos++] = encodeTable[context.ibitWorkArea & MASK_6BITS];
                     context.currentLinePos += BYTES_PER_ENCODED_BLOCK;
                     if (lineLength > 0 && lineLength <= context.currentLinePos) {
                         System.arraycopy(lineSeparator, 0, buffer, context.pos, lineSeparator.length);
                         context.pos += lineSeparator.length;
                         context.currentLinePos = 0;
                     }
                 }
             }
         }
     }
 
     /**
      * <p>
      * 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 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.
      * </p>
      * <p>
      * Ignores all non-base64 characters. This is how chunked (e.g. 76 character) data is handled, since CR and LF are
      * silently ignored, but has implications for other bytes, too. This method subscribes to the garbage-in,
      * garbage-out philosophy: it will not check the provided data for validity.
      * </p>
      * <p>
      * Thanks to "commons" project in ws.apache.org for the bitwise operations, and general approach.
      * http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
      * </p>
      *
      * @param in
      *            byte[] array of ascii data to base64 decode.
      * @param inPos
      *            Position to start reading data from.
      * @param inAvail
      *            Amount of bytes available from input for encoding.
      * @param context
      *            the context to be used
      */
     @Override
     void decode(final byte[] in, int inPos, final int inAvail, final Context context) {
         if (context.eof) {
             return;
         }
         if (inAvail < 0) {
             context.eof = true;
         }
         for (int i = 0; i < inAvail; i++) {
             final byte[] buffer = ensureBufferSize(decodeSize, context);
             final byte b = in[inPos++];
             if (b == pad) {
                 // We're done.
                 context.eof = true;
                 break;
             }
             if (b >= 0 && b < DECODE_TABLE.length) {
                 final int result = DECODE_TABLE[b];
                 if (result >= 0) {
                     context.modulus = (context.modulus+1) % BYTES_PER_ENCODED_BLOCK;
                     context.ibitWorkArea = (context.ibitWorkArea << BITS_PER_ENCODED_BYTE) + result;
                     if (context.modulus == 0) {
                         buffer[context.pos++] = (byte) ((context.ibitWorkArea >> 16) & MASK_8BITS);
                         buffer[context.pos++] = (byte) ((context.ibitWorkArea >> 8) & MASK_8BITS);
                         buffer[context.pos++] = (byte) (context.ibitWorkArea & MASK_8BITS);
                     }
                 }
             }
         }
 
         // Two forms of EOF as far as base64 decoder is concerned: actual
         // EOF (-1) and first time '=' character is encountered in stream.
         // This approach makes the '=' padding characters completely optional.
         if (context.eof && context.modulus != 0) {
             final byte[] buffer = ensureBufferSize(decodeSize, context);
 
             // We have some spare bits remaining
             // Output all whole multiples of 8 bits and ignore the rest
             switch (context.modulus) {
 //              case 0 : // impossible, as excluded above
                 case 1 : // 6 bits - ignore entirely
                     // TODO not currently tested; perhaps it is impossible?
                     break;
                 case 2 : // 12 bits = 8 + 4
                     context.ibitWorkArea = context.ibitWorkArea >> 4; // dump the extra 4 bits
                     buffer[context.pos++] = (byte) ((context.ibitWorkArea) & MASK_8BITS);
                     break;
                 case 3 : // 18 bits = 8 + 8 + 2
                     context.ibitWorkArea = context.ibitWorkArea >> 2; // dump 2 bits
                     buffer[context.pos++] = (byte) ((context.ibitWorkArea >> 8) & MASK_8BITS);
                     buffer[context.pos++] = (byte) ((context.ibitWorkArea) & MASK_8BITS);
                     break;
                 default:
                     throw new IllegalStateException("Impossible modulus "+context.modulus);
             }
         }
     }
 
     /**
      * Tests a given byte array to see if it contains only valid characters within the Base64 alphabet. Currently the
      * method treats whitespace as valid.
      *
      * @param arrayOctet
      *            byte array to test
      * @return <code>true</code> if all bytes are valid characters in the Base64 alphabet or if the byte array is empty;
      *         <code>false</code>, otherwise
      * @deprecated 1.5 Use {@link #isBase64(byte[])}, will be removed in 2.0.
      */
     @Deprecated
     public static boolean isArrayByteBase64(final byte[] arrayOctet) {
         return isBase64(arrayOctet);
     }
 
     /**
      * Returns whether or not the <code>octet</code> is in the base 64 alphabet.
      *
      * @param octet
      *            The value to test
      * @return <code>true</code> if the value is defined in the the base 64 alphabet, <code>false</code> otherwise.
      * @since 1.4
      */
     public static boolean isBase64(final byte octet) {
         return octet == PAD_DEFAULT || (octet >= 0 && octet < DECODE_TABLE.length && DECODE_TABLE[octet] != -1);
     }
 
     /**
      * Tests a given String to see if it contains only valid characters within the Base64 alphabet. Currently the
      * method treats whitespace as valid.
      *
      * @param base64
      *            String to test
      * @return <code>true</code> if all characters in the String are valid characters in the Base64 alphabet or if
      *         the String is empty; <code>false</code>, otherwise
      *  @since 1.5
      */
     public static boolean isBase64(final String base64) {
         return isBase64(StringUtils.getBytesUtf8(base64));
     }
 
     /**
      * Tests a given byte array to see if it contains only valid characters within the Base64 alphabet. Currently the
      * method treats whitespace as valid.
      *
      * @param arrayOctet
      *            byte array to test
      * @return <code>true</code> if all bytes are valid characters in the Base64 alphabet or if the byte array is empty;
      *         <code>false</code>, otherwise
      * @since 1.5
      */
     public static boolean isBase64(final byte[] arrayOctet) {
         for (int i = 0; i < arrayOctet.length; i++) {
             if (!isBase64(arrayOctet[i]) && !isWhiteSpace(arrayOctet[i])) {
                 return false;
             }
         }
         return true;
     }
 
     /**
      * Encodes binary data using the base64 algorithm but does not chunk the output.
      *
      * @param binaryData
      *            binary data to encode
      * @return byte[] containing Base64 characters in their UTF-8 representation.
      */
     public static byte[] encodeBase64(final byte[] binaryData) {
         return encodeBase64(binaryData, false);
     }
 
     /**
      * Encodes binary data using the base64 algorithm but does not chunk the output.
      *
      * NOTE:  We changed the behaviour of this method from multi-line chunking (commons-codec-1.4) to
      * single-line non-chunking (commons-codec-1.5).
      *
      * @param binaryData
      *            binary data to encode
      * @return String containing Base64 characters.
      * @since 1.4 (NOTE:  1.4 chunked the output, whereas 1.5 does not).
      */
     public static String encodeBase64String(final byte[] binaryData) {
         return StringUtils.newStringUsAscii(encodeBase64(binaryData, false));
     }
 
     /**
      * Encodes binary data using a URL-safe variation of the base64 algorithm but does not chunk the output. The
      * url-safe variation emits - and _ instead of + and / characters.
      * <b>Note: no padding is added.</b>
      * @param binaryData
      *            binary data to encode
      * @return byte[] containing Base64 characters in their UTF-8 representation.
      * @since 1.4
      */
     public static byte[] encodeBase64URLSafe(final byte[] binaryData) {
         return encodeBase64(binaryData, false, true);
     }
 
     /**
      * Encodes binary data using a URL-safe variation of the base64 algorithm but does not chunk the output. The
      * url-safe variation emits - and _ instead of + and / characters.
      * <b>Note: no padding is added.</b>
      * @param binaryData
      *            binary data to encode
      * @return String containing Base64 characters
      * @since 1.4
      */
     public static String encodeBase64URLSafeString(final byte[] binaryData) {
         return StringUtils.newStringUsAscii(encodeBase64(binaryData, false, true));
     }
 
     /**
      * Encodes binary data using the base64 algorithm and chunks the encoded output into 76 character blocks
      *
      * @param binaryData
      *            binary data to encode
      * @return Base64 characters chunked in 76 character blocks
      */
     public static byte[] encodeBase64Chunked(final byte[] binaryData) {
         return encodeBase64(binaryData, true);
     }
 
     /**
      * Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
      *
      * @param binaryData
      *            Array containing binary data to encode.
      * @param isChunked
      *            if <code>true</code> this encoder will chunk the base64 output into 76 character blocks
      * @return Base64-encoded data.
      * @throws IllegalArgumentException
      *             Thrown when the input array needs an output array bigger than {@link Integer#MAX_VALUE}
      */
     public static byte[] encodeBase64(final byte[] binaryData, final boolean isChunked) {
         return encodeBase64(binaryData, isChunked, false);
     }
 
     /**
      * Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
      *
      * @param binaryData
      *            Array containing binary data to encode.
      * @param isChunked
      *            if <code>true</code> this encoder will chunk the base64 output into 76 character blocks
      * @param urlSafe
      *            if <code>true</code> this encoder will emit - and _ instead of the usual + and / characters.
      *            <b>Note: no padding is added when encoding using the URL-safe alphabet.</b>
      * @return Base64-encoded data.
      * @throws IllegalArgumentException
      *             Thrown when the input array needs an output array bigger than {@link Integer#MAX_VALUE}
      * @since 1.4
      */
     public static byte[] encodeBase64(final byte[] binaryData, final boolean isChunked, final boolean urlSafe) {
         return encodeBase64(binaryData, isChunked, urlSafe, Integer.MAX_VALUE);
     }
 
     /**
      * Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
      *
      * @param binaryData
      *            Array containing binary data to encode.
      * @param isChunked
      *            if <code>true</code> this encoder will chunk the base64 output into 76 character blocks
      * @param urlSafe
      *            if <code>true</code> this encoder will emit - and _ instead of the usual + and / characters.
      *            <b>Note: no padding is added when encoding using the URL-safe alphabet.</b>
      * @param maxResultSize
      *            The maximum result size to accept.
      * @return Base64-encoded data.
      * @throws IllegalArgumentException
      *             Thrown when the input array needs an output array bigger than maxResultSize
      * @since 1.4
      */
     public static byte[] encodeBase64(final byte[] binaryData, final boolean isChunked,
                                       final boolean urlSafe, final int maxResultSize) {
         if (binaryData == null || binaryData.length == 0) {
             return binaryData;
         }
 
         // Create this so can use the super-class method
         // Also ensures that the same roundings are performed by the ctor and the code
         final Base64 b64 = isChunked ? new Base64(urlSafe) : new Base64(0, CHUNK_SEPARATOR, urlSafe);
         final long len = b64.getEncodedLength(binaryData);
         if (len > maxResultSize) {
             throw new IllegalArgumentException("Input array too big, the output array would be bigger (" +
                 len +
                 ") than the specified maximum size of " +
                 maxResultSize);
         }
 
         return b64.encode(binaryData);
     }
 
     /**
      * Decodes a Base64 String into octets.
      * <p>
      * <b>Note:</b> this method seamlessly handles data encoded in URL-safe or normal mode.
      * </p>
      *
      * @param base64String
      *            String containing Base64 data
      * @return Array containing decoded data.
      * @since 1.4
      */
     public static byte[] decodeBase64(final String base64String) {
         return new Base64().decode(base64String);
     }
 
     /**
      * Decodes Base64 data into octets.
      * <p>
      * <b>Note:</b> this method seamlessly handles data encoded in URL-safe or normal mode.
      * </p>
      *
      * @param base64Data
      *            Byte array containing Base64 data
      * @return Array containing decoded data.
      */
     public static byte[] decodeBase64(final byte[] base64Data) {
         return new Base64().decode(base64Data);
     }
 
     // Implementation of the Encoder Interface
 
     // Implementation of integer encoding used for crypto
     /**
      * Decodes a byte64-encoded integer according to crypto standards such as W3C's XML-Signature.
      *
      * @param pArray
      *            a byte array containing base64 character data
      * @return A BigInteger
      * @since 1.4
      */
     public static BigInteger decodeInteger(final byte[] pArray) {
         return new BigInteger(1, decodeBase64(pArray));
     }
 
     /**
      * Encodes to a byte64-encoded integer according to crypto standards such as W3C's XML-Signature.
      *
      * @param bigInt
      *            a BigInteger
      * @return A byte array containing base64 character data
      * @throws NullPointerException
      *             if null is passed in
      * @since 1.4
      */
     public static byte[] encodeInteger(final BigInteger bigInt) {
         if (bigInt == null) {
             throw new NullPointerException("encodeInteger called with null parameter");
         }
         return encodeBase64(toIntegerBytes(bigInt), false);
     }
 
     /**
      * Returns a byte-array representation of a <code>BigInteger</code> without sign bit.
      *
      * @param bigInt
      *            <code>BigInteger</code> to be converted
      * @return a byte array representation of the BigInteger parameter
      */
     static byte[] toIntegerBytes(final BigInteger bigInt) {
         int bitlen = bigInt.bitLength();
         // round bitlen
         bitlen = ((bitlen + 7) >> 3) << 3;
         final byte[] bigBytes = bigInt.toByteArray();
 
         if (((bigInt.bitLength() % 8) != 0) && (((bigInt.bitLength() / 8) + 1) == (bitlen / 8))) {
             return bigBytes;
         }
         // set up params for copying everything but sign bit
         int startSrc = 0;
         int len = bigBytes.length;
 
         // if bigInt is exactly byte-aligned, just skip signbit in copy
         if ((bigInt.bitLength() % 8) == 0) {
             startSrc = 1;
             len--;
         }
         final int startDst = bitlen / 8 - len; // to pad w/ nulls as per spec
         final byte[] resizedBytes = new byte[bitlen / 8];
         System.arraycopy(bigBytes, startSrc, resizedBytes, startDst, len);
         return resizedBytes;
     }
 
     /**
      * Returns whether or not the <code>octet</code> is in the Base64 alphabet.
      *
      * @param octet
      *            The value to test
      * @return <code>true</code> if the value is defined in the the Base64 alphabet <code>false</code> otherwise.
      */
     @Override
     protected boolean isInAlphabet(final byte octet) {
         return octet >= 0 && octet < decodeTable.length && decodeTable[octet] != -1;
     }
 
 }