EncodingUtils.java | searchcode

/source/library/com/restfb/util/EncodingUtils.java

https://github.com/revetkn/restfb
Java | 717 lines | 326 code | 91 blank | 300 comment | 129 complexity | 29eeeaed0bec9d093477497900337404 MD5 | raw file
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/*
 * Copyright (c) 2010-2014 Mark Allen.
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

package com.restfb.util;

import java.io.UnsupportedEncodingException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;

/**
 * A collection of data-encoding utility methods.
 * 
 * @author Josef Gierbl
 * @author Mikael Grev
 * @author <a href="http://restfb.com">Mark Allen</a>
 * @since 1.6.13
 */
public final class EncodingUtils {
  /**
   * Prevents instantiation.
   */
  private EncodingUtils() {}

  /**
   * Decodes a base64-encoded string, padding out if necessary.
   * 
   * @param base64
   *          The base64-encoded string to decode.
   * @return A decoded version of {@code base64}.
   * @throws NullPointerException
   *           If {@code base64} is {@code null}.
   */
  public static byte[] decodeBase64(String base64) {
    if (base64 == null)
      throw new NullPointerException("Parameter 'base64' cannot be null.");

    base64 = padBase64(base64);
    return Base64.decode(base64);
  }

  private static String padBase64(String base64) {
    String padding = "";
    int remainder = base64.length() % 4;

    if (remainder == 1)
      padding = "===";
    else if (remainder == 2)
      padding = "==";
    else if (remainder == 3)
      padding = "=";

    return base64 + padding;
  }

  /**
   * Encodes a hex {@code byte[]} from given {@code byte[]}.
   * 
   * This function is equivalent to Apache commons-codec binary {@code new Hex().encode(byte[])}
   * 
   * @param data
   *          The data to encode as hex.
   * @return Hex-encoded {@code byte[]}
   * @throws NullPointerException
   *           If {@code data} is {@code null}.
   */
  public static byte[] encodeHex(final byte[] data) {
    if (data == null)
      throw new NullPointerException("Parameter 'data' cannot be null.");

    final char[] toDigits = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
    final int l = data.length;
    final char[] out = new char[l << 1];
    for (int i = 0, j = 0; i < l; i++) {
      out[j++] = toDigits[(0xF0 & data[i]) >>> 4];
      out[j++] = toDigits[0x0F & data[i]];
    }

    return new String(out).getBytes();
  }

  /**
   * Generates an appsecret_proof for facebook.
   * 
   * See https://developers.facebook.com/docs/graph-api/securing-requests for more info
   * 
   * @param appSecret
   *          The facebook application secret
   * @param accessToken
   *          The facebook access token
   * @return A Hex encoded SHA256 Hash as a String
   * @throws NoSuchAlgorithmException
   * @throws InvalidKeyException
   * @throws UnsupportedEncodingException
   */
  public static String encodeAppSecretProof(String appSecret, String accessToken) throws NoSuchAlgorithmException,
      InvalidKeyException, UnsupportedEncodingException {
    byte[] key = appSecret.getBytes();
    SecretKeySpec signingKey = new SecretKeySpec(key, "HmacSHA256");
    Mac mac = Mac.getInstance("HmacSHA256");
    mac.init(signingKey);
    byte[] raw = mac.doFinal(accessToken.getBytes());
    byte[] hex = encodeHex(raw);
    String out = new String(hex, "UTF-8");
    return out;
  }

  /**
   * A very fast and memory efficient class to encode and decode to and from BASE64 in full accordance with RFC 2045.<br>
   * <br>
   * On Windows XP sp1 with 1.4.2_04 and later ;), this encoder and decoder is about 10 times faster on small arrays (10
   * - 1000 bytes) and 2-3 times as fast on larger arrays (10000 - 1000000 bytes) compared to
   * <code>sun.misc.Encoder()/Decoder()</code>.<br>
   * <br>
   * 
   * On byte arrays the encoder is about 20% faster than Jakarta Commons Base64 Codec for encode and about 50% faster
   * for decoding large arrays. This implementation is about twice as fast on very small arrays (&lt 30 bytes). If
   * source/destination is a <code>String</code> this version is about three times as fast due to the fact that the
   * Commons Codec result has to be recoded to a <code>String</code> from <code>byte[]</code>, which is very expensive.<br>
   * <br>
   * 
   * This encode/decode algorithm doesn't create any temporary arrays as many other codecs do, it only allocates the
   * resulting array. This produces less garbage and it is possible to handle arrays twice as large as algorithms that
   * create a temporary array. (E.g. Jakarta Commons Codec). It is unknown whether Sun's
   * <code>sun.misc.Encoder()/Decoder()</code> produce temporary arrays but since performance is quite low it probably
   * does.<br>
   * <br>
   * 
   * The encoder produces the same output as the Sun one except that the Sun's encoder appends a trailing line separator
   * if the last character isn't a pad. Unclear why but it only adds to the length and is probably a side effect. Both
   * are in conformance with RFC 2045 though.<br>
   * Commons codec seem to always att a trailing line separator.<br>
   * <br>
   * 
   * <b>Note!</b> The encode/decode method pairs (types) come in three versions with the <b>exact</b> same algorithm and
   * thus a lot of code redundancy. This is to not create any temporary arrays for transcoding to/from different format
   * types. The methods not used can simply be commented out.<br>
   * <br>
   * 
   * There is also a "fast" version of all decode methods that works the same way as the normal ones, but har a few
   * demands on the decoded input. Normally though, these fast verions should be used if the source if the input is
   * known and it hasn't bee tampered with.<br>
   * <br>
   * 
   * If you find the code useful or you find a bug, please send me a note at base64 @ miginfocom . com.
   * 
   * Licence (BSD): ==============
   * 
   * Copyright (c) 2004, Mikael Grev, MiG InfoCom AB. (base64 @ miginfocom . com) All rights reserved.
   * 
   * Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
   * following conditions are met: Redistributions of source code must retain the above copyright notice, this list of
   * conditions and the following disclaimer. Redistributions in binary form must reproduce the above copyright notice,
   * this list of conditions and the following disclaimer in the documentation and/or other materials provided with the
   * distribution. Neither the name of the MiG InfoCom AB nor the names of its contributors may be used to endorse or
   * promote products derived from this software without specific prior written permission.
   * 
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
   * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
   * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
   * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
   * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   * 
   * @version 2.2
   * @author Mikael Grev Date: 2004-aug-02 Time: 11:31:11
   */
  @SuppressWarnings("unused")
  private static class Base64 {
    private static final char[] CA = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray();
    private static final int[] IA = new int[256];
    static {
      Arrays.fill(IA, -1);
      for (int i = 0, iS = CA.length; i < iS; i++)
        IA[CA[i]] = i;
      IA['='] = 0;
    }

    // ****************************************************************************************
    // * char[] version
    // ****************************************************************************************

    /**
     * Encodes a raw byte array into a BASE64 <code>char[]</code> representation i accordance with RFC 2045.
     * 
     * @param sArr
     *          The bytes to convert. If <code>null</code> or length 0 an empty array will be returned.
     * @param lineSep
     *          Optional "\r\n" after 76 characters, unless end of file.<br>
     *          No line separator will be in breach of RFC 2045 which specifies max 76 per line but will be a little
     *          faster.
     * @return A BASE64 encoded array. Never <code>null</code>.
     */
    public final static char[] encodeToChar(byte[] sArr, boolean lineSep) {
      // Check special case
      int sLen = sArr != null ? sArr.length : 0;
      if (sLen == 0)
        return new char[0];

      int eLen = (sLen / 3) * 3; // Length of even 24-bits.
      int cCnt = ((sLen - 1) / 3 + 1) << 2; // Returned character count
      int dLen = cCnt + (lineSep ? (cCnt - 1) / 76 << 1 : 0); // Length of returned array
      char[] dArr = new char[dLen];

      // Encode even 24-bits
      for (int s = 0, d = 0, cc = 0; s < eLen;) {
        // Copy next three bytes into lower 24 bits of int, paying attension to sign.
        int i = (sArr[s++] & 0xff) << 16 | (sArr[s++] & 0xff) << 8 | (sArr[s++] & 0xff);

        // Encode the int into four chars
        dArr[d++] = CA[(i >>> 18) & 0x3f];
        dArr[d++] = CA[(i >>> 12) & 0x3f];
        dArr[d++] = CA[(i >>> 6) & 0x3f];
        dArr[d++] = CA[i & 0x3f];

        // Add optional line separator
        if (lineSep && ++cc == 19 && d < dLen - 2) {
          dArr[d++] = '\r';
          dArr[d++] = '\n';
          cc = 0;
        }
      }

      // Pad and encode last bits if source isn't even 24 bits.
      int left = sLen - eLen; // 0 - 2.
      if (left > 0) {
        // Prepare the int
        int i = ((sArr[eLen] & 0xff) << 10) | (left == 2 ? ((sArr[sLen - 1] & 0xff) << 2) : 0);

        // Set last four chars
        dArr[dLen - 4] = CA[i >> 12];
        dArr[dLen - 3] = CA[(i >>> 6) & 0x3f];
        dArr[dLen - 2] = left == 2 ? CA[i & 0x3f] : '=';
        dArr[dLen - 1] = '=';
      }
      return dArr;
    }

    /**
     * Decodes a BASE64 encoded char array. All illegal characters will be ignored and can handle both arrays with and
     * without line separators.
     * 
     * @param sArr
     *          The source array. <code>null</code> or length 0 will return an empty array.
     * @return The decoded array of bytes. May be of length 0. Will be <code>null</code> if the legal characters
     *         (including '=') isn't divideable by 4. (I.e. definitely corrupted).
     */
    public final static byte[] decode(char[] sArr) {
      // Check special case
      int sLen = sArr != null ? sArr.length : 0;
      if (sLen == 0)
        return new byte[0];

      // Count illegal characters (including '\r', '\n') to know what size the returned array will be,
      // so we don't have to reallocate & copy it later.
      int sepCnt = 0; // Number of separator characters. (Actually illegal characters, but that's a bonus...)
      for (int i = 0; i < sLen; i++)
        // If input is "pure" (I.e. no line separators or illegal chars) base64 this loop can be commented out.
        if (IA[sArr[i]] < 0)
          sepCnt++;

      // Check so that legal chars (including '=') are evenly divideable by 4 as specified in RFC 2045.
      if ((sLen - sepCnt) % 4 != 0)
        return null;

      int pad = 0;
      for (int i = sLen; i > 1 && IA[sArr[--i]] <= 0;)
        if (sArr[i] == '=')
          pad++;

      int len = ((sLen - sepCnt) * 6 >> 3) - pad;

      byte[] dArr = new byte[len]; // Preallocate byte[] of exact length

      for (int s = 0, d = 0; d < len;) {
        // Assemble three bytes into an int from four "valid" characters.
        int i = 0;
        for (int j = 0; j < 4; j++) { // j only increased if a valid char was found.
          int c = IA[sArr[s++]];
          if (c >= 0)
            i |= c << (18 - j * 6);
          else
            j--;
        }
        // Add the bytes
        dArr[d++] = (byte) (i >> 16);
        if (d < len) {
          dArr[d++] = (byte) (i >> 8);
          if (d < len)
            dArr[d++] = (byte) i;
        }
      }
      return dArr;
    }

    /**
     * Decodes a BASE64 encoded char array that is known to be resonably well formatted. The method is about twice as
     * fast as {@link #decode(char[])}. The preconditions are:<br>
     * + The array must have a line length of 76 chars OR no line separators at all (one line).<br>
     * + Line separator must be "\r\n", as specified in RFC 2045 + The array must not contain illegal characters within
     * the encoded string<br>
     * + The array CAN have illegal characters at the beginning and end, those will be dealt with appropriately.<br>
     * 
     * @param sArr
     *          The source array. Length 0 will return an empty array. <code>null</code> will throw an exception.
     * @return The decoded array of bytes. May be of length 0.
     */
    public final static byte[] decodeFast(char[] sArr) {
      // Check special case
      int sLen = sArr.length;
      if (sLen == 0)
        return new byte[0];

      int sIx = 0, eIx = sLen - 1; // Start and end index after trimming.

      // Trim illegal chars from start
      while (sIx < eIx && IA[sArr[sIx]] < 0)
        sIx++;

      // Trim illegal chars from end
      while (eIx > 0 && IA[sArr[eIx]] < 0)
        eIx--;

      // get the padding count (=) (0, 1 or 2)
      int pad = sArr[eIx] == '=' ? (sArr[eIx - 1] == '=' ? 2 : 1) : 0; // Count '=' at end.
      int cCnt = eIx - sIx + 1; // Content count including possible separators
      int sepCnt = sLen > 76 ? (sArr[76] == '\r' ? cCnt / 78 : 0) << 1 : 0;

      int len = ((cCnt - sepCnt) * 6 >> 3) - pad; // The number of decoded bytes
      byte[] dArr = new byte[len]; // Preallocate byte[] of exact length

      // Decode all but the last 0 - 2 bytes.
      int d = 0;
      for (int cc = 0, eLen = (len / 3) * 3; d < eLen;) {
        // Assemble three bytes into an int from four "valid" characters.
        int i = IA[sArr[sIx++]] << 18 | IA[sArr[sIx++]] << 12 | IA[sArr[sIx++]] << 6 | IA[sArr[sIx++]];

        // Add the bytes
        dArr[d++] = (byte) (i >> 16);
        dArr[d++] = (byte) (i >> 8);
        dArr[d++] = (byte) i;

        // If line separator, jump over it.
        if (sepCnt > 0 && ++cc == 19) {
          sIx += 2;
          cc = 0;
        }
      }

      if (d < len) {
        // Decode last 1-3 bytes (incl '=') into 1-3 bytes
        int i = 0;
        for (int j = 0; sIx <= eIx - pad; j++)
          i |= IA[sArr[sIx++]] << (18 - j * 6);

        for (int r = 16; d < len; r -= 8)
          dArr[d++] = (byte) (i >> r);
      }

      return dArr;
    }

    // ****************************************************************************************
    // * byte[] version
    // ****************************************************************************************

    /**
     * Encodes a raw byte array into a BASE64 <code>byte[]</code> representation i accordance with RFC 2045.
     * 
     * @param sArr
     *          The bytes to convert. If <code>null</code> or length 0 an empty array will be returned.
     * @param lineSep
     *          Optional "\r\n" after 76 characters, unless end of file.<br>
     *          No line separator will be in breach of RFC 2045 which specifies max 76 per line but will be a little
     *          faster.
     * @return A BASE64 encoded array. Never <code>null</code>.
     */
    public final static byte[] encodeToByte(byte[] sArr, boolean lineSep) {
      // Check special case
      int sLen = sArr != null ? sArr.length : 0;
      if (sLen == 0)
        return new byte[0];

      int eLen = (sLen / 3) * 3; // Length of even 24-bits.
      int cCnt = ((sLen - 1) / 3 + 1) << 2; // Returned character count
      int dLen = cCnt + (lineSep ? (cCnt - 1) / 76 << 1 : 0); // Length of returned array
      byte[] dArr = new byte[dLen];

      // Encode even 24-bits
      for (int s = 0, d = 0, cc = 0; s < eLen;) {
        // Copy next three bytes into lower 24 bits of int, paying attension to sign.
        int i = (sArr[s++] & 0xff) << 16 | (sArr[s++] & 0xff) << 8 | (sArr[s++] & 0xff);

        // Encode the int into four chars
        dArr[d++] = (byte) CA[(i >>> 18) & 0x3f];
        dArr[d++] = (byte) CA[(i >>> 12) & 0x3f];
        dArr[d++] = (byte) CA[(i >>> 6) & 0x3f];
        dArr[d++] = (byte) CA[i & 0x3f];

        // Add optional line separator
        if (lineSep && ++cc == 19 && d < dLen - 2) {
          dArr[d++] = '\r';
          dArr[d++] = '\n';
          cc = 0;
        }
      }

      // Pad and encode last bits if source isn't an even 24 bits.
      int left = sLen - eLen; // 0 - 2.
      if (left > 0) {
        // Prepare the int
        int i = ((sArr[eLen] & 0xff) << 10) | (left == 2 ? ((sArr[sLen - 1] & 0xff) << 2) : 0);

        // Set last four chars
        dArr[dLen - 4] = (byte) CA[i >> 12];
        dArr[dLen - 3] = (byte) CA[(i >>> 6) & 0x3f];
        dArr[dLen - 2] = left == 2 ? (byte) CA[i & 0x3f] : (byte) '=';
        dArr[dLen - 1] = '=';
      }
      return dArr;
    }

    /**
     * Decodes a BASE64 encoded byte array. All illegal characters will be ignored and can handle both arrays with and
     * without line separators.
     * 
     * @param sArr
     *          The source array. Length 0 will return an empty array. <code>null</code> will throw an exception.
     * @return The decoded array of bytes. May be of length 0. Will be <code>null</code> if the legal characters
     *         (including '=') isn't divideable by 4. (I.e. definitely corrupted).
     */
    public final static byte[] decode(byte[] sArr) {
      // Check special case
      int sLen = sArr.length;

      // Count illegal characters (including '\r', '\n') to know what size the returned array will be,
      // so we don't have to reallocate & copy it later.
      int sepCnt = 0; // Number of separator characters. (Actually illegal characters, but that's a bonus...)
      for (int i = 0; i < sLen; i++)
        // If input is "pure" (I.e. no line separators or illegal chars) base64 this loop can be commented out.
        if (IA[sArr[i] & 0xff] < 0)
          sepCnt++;

      // Check so that legal chars (including '=') are evenly divideable by 4 as specified in RFC 2045.
      if ((sLen - sepCnt) % 4 != 0)
        return null;

      int pad = 0;
      for (int i = sLen; i > 1 && IA[sArr[--i] & 0xff] <= 0;)
        if (sArr[i] == '=')
          pad++;

      int len = ((sLen - sepCnt) * 6 >> 3) - pad;

      byte[] dArr = new byte[len]; // Preallocate byte[] of exact length

      for (int s = 0, d = 0; d < len;) {
        // Assemble three bytes into an int from four "valid" characters.
        int i = 0;
        for (int j = 0; j < 4; j++) { // j only increased if a valid char was found.
          int c = IA[sArr[s++] & 0xff];
          if (c >= 0)
            i |= c << (18 - j * 6);
          else
            j--;
        }

        // Add the bytes
        dArr[d++] = (byte) (i >> 16);
        if (d < len) {
          dArr[d++] = (byte) (i >> 8);
          if (d < len)
            dArr[d++] = (byte) i;
        }
      }

      return dArr;
    }

    /**
     * Decodes a BASE64 encoded byte array that is known to be resonably well formatted. The method is about twice as
     * fast as {@link #decode(byte[])}. The preconditions are:<br>
     * + The array must have a line length of 76 chars OR no line separators at all (one line).<br>
     * + Line separator must be "\r\n", as specified in RFC 2045 + The array must not contain illegal characters within
     * the encoded string<br>
     * + The array CAN have illegal characters at the beginning and end, those will be dealt with appropriately.<br>
     * 
     * @param sArr
     *          The source array. Length 0 will return an empty array. <code>null</code> will throw an exception.
     * @return The decoded array of bytes. May be of length 0.
     */
    public final static byte[] decodeFast(byte[] sArr) {
      // Check special case
      int sLen = sArr.length;
      if (sLen == 0)
        return new byte[0];

      int sIx = 0, eIx = sLen - 1; // Start and end index after trimming.

      // Trim illegal chars from start
      while (sIx < eIx && IA[sArr[sIx] & 0xff] < 0)
        sIx++;

      // Trim illegal chars from end
      while (eIx > 0 && IA[sArr[eIx] & 0xff] < 0)
        eIx--;

      // get the padding count (=) (0, 1 or 2)
      int pad = sArr[eIx] == '=' ? (sArr[eIx - 1] == '=' ? 2 : 1) : 0; // Count '=' at end.
      int cCnt = eIx - sIx + 1; // Content count including possible separators
      int sepCnt = sLen > 76 ? (sArr[76] == '\r' ? cCnt / 78 : 0) << 1 : 0;

      int len = ((cCnt - sepCnt) * 6 >> 3) - pad; // The number of decoded bytes
      byte[] dArr = new byte[len]; // Preallocate byte[] of exact length

      // Decode all but the last 0 - 2 bytes.
      int d = 0;
      for (int cc = 0, eLen = (len / 3) * 3; d < eLen;) {
        // Assemble three bytes into an int from four "valid" characters.
        int i = IA[sArr[sIx++]] << 18 | IA[sArr[sIx++]] << 12 | IA[sArr[sIx++]] << 6 | IA[sArr[sIx++]];

        // Add the bytes
        dArr[d++] = (byte) (i >> 16);
        dArr[d++] = (byte) (i >> 8);
        dArr[d++] = (byte) i;

        // If line separator, jump over it.
        if (sepCnt > 0 && ++cc == 19) {
          sIx += 2;
          cc = 0;
        }
      }

      if (d < len) {
        // Decode last 1-3 bytes (incl '=') into 1-3 bytes
        int i = 0;
        for (int j = 0; sIx <= eIx - pad; j++)
          i |= IA[sArr[sIx++]] << (18 - j * 6);

        for (int r = 16; d < len; r -= 8)
          dArr[d++] = (byte) (i >> r);
      }

      return dArr;
    }

    // ****************************************************************************************
    // * String version
    // ****************************************************************************************

    /**
     * Encodes a raw byte array into a BASE64 <code>String</code> representation i accordance with RFC 2045.
     * 
     * @param sArr
     *          The bytes to convert. If <code>null</code> or length 0 an empty array will be returned.
     * @param lineSep
     *          Optional "\r\n" after 76 characters, unless end of file.<br>
     *          No line separator will be in breach of RFC 2045 which specifies max 76 per line but will be a little
     *          faster.
     * @return A BASE64 encoded array. Never <code>null</code>.
     */
    public final static String encodeToString(byte[] sArr, boolean lineSep) {
      // Reuse char[] since we can't create a String incrementally anyway and StringBuffer/Builder would be slower.
      return new String(encodeToChar(sArr, lineSep));
    }

    /**
     * Decodes a BASE64 encoded <code>String</code>. All illegal characters will be ignored and can handle both strings
     * with and without line separators.<br>
     * <b>Note!</b> It can be up to about 2x the speed to call <code>decode(str.toCharArray())</code> instead. That will
     * create a temporary array though. This version will use <code>str.charAt(i)</code> to iterate the string.
     * 
     * @param str
     *          The source string. <code>null</code> or length 0 will return an empty array.
     * @return The decoded array of bytes. May be of length 0. Will be <code>null</code> if the legal characters
     *         (including '=') isn't divideable by 4. (I.e. definitely corrupted).
     */
    public final static byte[] decode(String str) {
      // Check special case
      int sLen = str != null ? str.length() : 0;
      if (sLen == 0)
        return new byte[0];

      // Count illegal characters (including '\r', '\n') to know what size the returned array will be,
      // so we don't have to reallocate & copy it later.
      int sepCnt = 0; // Number of separator characters. (Actually illegal characters, but that's a bonus...)
      for (int i = 0; i < sLen; i++)
        // If input is "pure" (I.e. no line separators or illegal chars) base64 this loop can be commented out.
        if (IA[str.charAt(i)] < 0)
          sepCnt++;

      // Check so that legal chars (including '=') are evenly divideable by 4 as specified in RFC 2045.
      if ((sLen - sepCnt) % 4 != 0)
        return null;

      // Count '=' at end
      int pad = 0;
      for (int i = sLen; i > 1 && IA[str.charAt(--i)] <= 0;)
        if (str.charAt(i) == '=')
          pad++;

      int len = ((sLen - sepCnt) * 6 >> 3) - pad;

      byte[] dArr = new byte[len]; // Preallocate byte[] of exact length

      for (int s = 0, d = 0; d < len;) {
        // Assemble three bytes into an int from four "valid" characters.
        int i = 0;
        for (int j = 0; j < 4; j++) { // j only increased if a valid char was found.
          int c = IA[str.charAt(s++)];
          if (c >= 0)
            i |= c << (18 - j * 6);
          else
            j--;
        }
        // Add the bytes
        dArr[d++] = (byte) (i >> 16);
        if (d < len) {
          dArr[d++] = (byte) (i >> 8);
          if (d < len)
            dArr[d++] = (byte) i;
        }
      }
      return dArr;
    }

    /**
     * Decodes a BASE64 encoded string that is known to be resonably well formatted. The method is about twice as fast
     * as {@link #decode(String)}. The preconditions are:<br>
     * + The array must have a line length of 76 chars OR no line separators at all (one line).<br>
     * + Line separator must be "\r\n", as specified in RFC 2045 + The array must not contain illegal characters within
     * the encoded string<br>
     * + The array CAN have illegal characters at the beginning and end, those will be dealt with appropriately.<br>
     * 
     * @param s
     *          The source string. Length 0 will return an empty array. <code>null</code> will throw an exception.
     * @return The decoded array of bytes. May be of length 0.
     */
    public final static byte[] decodeFast(String s) {
      // Check special case
      int sLen = s.length();
      if (sLen == 0)
        return new byte[0];

      int sIx = 0, eIx = sLen - 1; // Start and end index after trimming.

      // Trim illegal chars from start
      while (sIx < eIx && IA[s.charAt(sIx) & 0xff] < 0)
        sIx++;

      // Trim illegal chars from end
      while (eIx > 0 && IA[s.charAt(eIx) & 0xff] < 0)
        eIx--;

      // get the padding count (=) (0, 1 or 2)
      int pad = s.charAt(eIx) == '=' ? (s.charAt(eIx - 1) == '=' ? 2 : 1) : 0; // Count '=' at end.
      int cCnt = eIx - sIx + 1; // Content count including possible separators
      int sepCnt = sLen > 76 ? (s.charAt(76) == '\r' ? cCnt / 78 : 0) << 1 : 0;

      int len = ((cCnt - sepCnt) * 6 >> 3) - pad; // The number of decoded bytes
      byte[] dArr = new byte[len]; // Preallocate byte[] of exact length

      // Decode all but the last 0 - 2 bytes.
      int d = 0;
      for (int cc = 0, eLen = (len / 3) * 3; d < eLen;) {
        // Assemble three bytes into an int from four "valid" characters.
        int i = IA[s.charAt(sIx++)] << 18 | IA[s.charAt(sIx++)] << 12 | IA[s.charAt(sIx++)] << 6 | IA[s.charAt(sIx++)];

        // Add the bytes
        dArr[d++] = (byte) (i >> 16);
        dArr[d++] = (byte) (i >> 8);
        dArr[d++] = (byte) i;

        // If line separator, jump over it.
        if (sepCnt > 0 && ++cc == 19) {
          sIx += 2;
          cc = 0;
        }
      }

      if (d < len) {
        // Decode last 1-3 bytes (incl '=') into 1-3 bytes
        int i = 0;
        for (int j = 0; sIx <= eIx - pad; j++)
          i |= IA[s.charAt(sIx++)] << (18 - j * 6);

        for (int r = 16; d < len; r -= 8)
          dArr[d++] = (byte) (i >> r);
      }

      return dArr;
    }
  }
}