Java tutorial
/* * Copyright 2002-2016 the original author or authors. * * Licensed 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 * * https://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.springframework.security.crypto.codec; /** * Base64 encoder which is a reduced version of Robert Harder's public domain * implementation (version 2.3.7). See <a * href="http://iharder.sourceforge.net/current/java/base64/">http://iharder.sourceforge.net/current/java/base64/</a> for more information. * <p> * For internal use only. * * @author Luke Taylor * @since 3.0 * @deprecated Use java.util.Base64 */ @Deprecated public final class Base64 { /** No options specified. Value is zero. */ public final static int NO_OPTIONS = 0; /** Specify encoding in first bit. Value is one. */ public final static int ENCODE = 1; /** Specify decoding in first bit. Value is zero. */ public final static int DECODE = 0; /** Do break lines when encoding. Value is 8. */ public final static int DO_BREAK_LINES = 8; /** * Encode using Base64-like encoding that is URL- and Filename-safe as described in * Section 4 of RFC3548: <a * href="https://tools.ietf.org/html/rfc3548">https://tools.ietf.org/html/rfc3548</a>. * It is important to note that data encoded this way is * <em>not</em> officially valid Base64, or at the very least should not be called * Base64 without also specifying that is was encoded using the URL- and Filename-safe * dialect. */ public final static int URL_SAFE = 16; /** * Encode using the special "ordered" dialect of Base64. */ public final static int ORDERED = 32; /** Maximum line length (76) of Base64 output. */ private final static int MAX_LINE_LENGTH = 76; /** The equals sign (=) as a byte. */ private final static byte EQUALS_SIGN = (byte) '='; /** The new line character (\n) as a byte. */ private final static byte NEW_LINE = (byte) '\n'; private final static byte WHITE_SPACE_ENC = -5; // Indicates white space in encoding private final static byte EQUALS_SIGN_ENC = -1; // Indicates equals sign in encoding /* ******** S T A N D A R D B A S E 6 4 A L P H A B E T ******** */ /** The 64 valid Base64 values. */ /* Host platform me be something funny like EBCDIC, so we hardcode these values. */ private final static byte[] _STANDARD_ALPHABET = { (byte) 'A', (byte) 'B', (byte) 'C', (byte) 'D', (byte) 'E', (byte) 'F', (byte) 'G', (byte) 'H', (byte) 'I', (byte) 'J', (byte) 'K', (byte) 'L', (byte) 'M', (byte) 'N', (byte) 'O', (byte) 'P', (byte) 'Q', (byte) 'R', (byte) 'S', (byte) 'T', (byte) 'U', (byte) 'V', (byte) 'W', (byte) 'X', (byte) 'Y', (byte) 'Z', (byte) 'a', (byte) 'b', (byte) 'c', (byte) 'd', (byte) 'e', (byte) 'f', (byte) 'g', (byte) 'h', (byte) 'i', (byte) 'j', (byte) 'k', (byte) 'l', (byte) 'm', (byte) 'n', (byte) 'o', (byte) 'p', (byte) 'q', (byte) 'r', (byte) 's', (byte) 't', (byte) 'u', (byte) 'v', (byte) 'w', (byte) 'x', (byte) 'y', (byte) 'z', (byte) '0', (byte) '1', (byte) '2', (byte) '3', (byte) '4', (byte) '5', (byte) '6', (byte) '7', (byte) '8', (byte) '9', (byte) '+', (byte) '/' }; /** * Translates a Base64 value to either its 6-bit reconstruction value or a negative * number indicating some other meaning. **/ private final static byte[] _STANDARD_DECODABET = { -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 0 - 8 -5, -5, // Whitespace: Tab and Linefeed -9, -9, // Decimal 11 - 12 -5, // Whitespace: Carriage Return -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 14 - 26 -9, -9, -9, -9, -9, // Decimal 27 - 31 -5, // Whitespace: Space -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 33 - 42 62, // Plus sign at decimal 43 -9, -9, -9, // Decimal 44 - 46 63, // Slash at decimal 47 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, // Numbers zero through nine -9, -9, -9, // Decimal 58 - 60 -1, // Equals sign at decimal 61 -9, -9, -9, // Decimal 62 - 64 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, // Letters 'A' through 'N' 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, // Letters 'O' through 'Z' -9, -9, -9, -9, -9, -9, // Decimal 91 - 96 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, // Letters 'a' through 'm' 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, // Letters 'n' through 'z' -9, -9, -9, -9, -9 // Decimal 123 - 127 , -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 128 - 139 -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 140 - 152 -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 153 - 165 -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 166 - 178 -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 179 - 191 -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 192 - 204 -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 205 - 217 -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 218 - 230 -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 231 - 243 -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9 // Decimal 244 - 255 }; /* ******** U R L S A F E B A S E 6 4 A L P H A B E T ******** */ /** * Used in the URL- and Filename-safe dialect described in Section 4 of RFC3548: <a * href * ="https://tools.ietf.org/html/rfc3548">https://tools.ietf.org/html/rfc3548</a>. * Notice that the last two bytes become "hyphen" and "underscore" instead of "plus" * and "slash." */ private final static byte[] _URL_SAFE_ALPHABET = { (byte) 'A', (byte) 'B', (byte) 'C', (byte) 'D', (byte) 'E', (byte) 'F', (byte) 'G', (byte) 'H', (byte) 'I', (byte) 'J', (byte) 'K', (byte) 'L', (byte) 'M', (byte) 'N', (byte) 'O', (byte) 'P', (byte) 'Q', (byte) 'R', (byte) 'S', (byte) 'T', (byte) 'U', (byte) 'V', (byte) 'W', (byte) 'X', (byte) 'Y', (byte) 'Z', (byte) 'a', (byte) 'b', (byte) 'c', (byte) 'd', (byte) 'e', (byte) 'f', (byte) 'g', (byte) 'h', (byte) 'i', (byte) 'j', (byte) 'k', (byte) 'l', (byte) 'm', (byte) 'n', (byte) 'o', (byte) 'p', (byte) 'q', (byte) 'r', (byte) 's', (byte) 't', (byte) 'u', (byte) 'v', (byte) 'w', (byte) 'x', (byte) 'y', (byte) 'z', (byte) '0', (byte) '1', (byte) '2', (byte) '3', (byte) '4', (byte) '5', (byte) '6', (byte) '7', (byte) '8', (byte) '9', (byte) '-', (byte) '_' }; /** * Used in decoding URL- and Filename-safe dialects of Base64. */ private final static byte[] _URL_SAFE_DECODABET = { -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 0 - 8 -5, -5, // Whitespace: Tab and Linefeed -9, -9, // Decimal 11 - 12 -5, // Whitespace: Carriage Return -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 14 - 26 -9, -9, -9, -9, -9, // Decimal 27 - 31 -5, // Whitespace: Space -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 33 - 42 -9, // Plus sign at decimal 43 -9, // Decimal 44 62, // Minus sign at decimal 45 -9, // Decimal 46 -9, // Slash at decimal 47 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, // Numbers zero through nine -9, -9, -9, // Decimal 58 - 60 -1, // Equals sign at decimal 61 -9, -9, -9, // Decimal 62 - 64 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, // Letters 'A' through 'N' 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, // Letters 'O' through 'Z' -9, -9, -9, -9, // Decimal 91 - 94 63, // Underscore at decimal 95 -9, // Decimal 96 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, // Letters 'a' through 'm' 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, // Letters 'n' through 'z' -9, -9, -9, -9, -9 // Decimal 123 - 127 , -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 128 - 139 -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 140 - 152 -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 153 - 165 -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 166 - 178 -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 179 - 191 -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 192 - 204 -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 205 - 217 -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 218 - 230 -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 231 - 243 -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9 // Decimal 244 - 255 }; /* ******** O R D E R E D B A S E 6 4 A L P H A B E T ******** */ private final static byte[] _ORDERED_ALPHABET = { (byte) '-', (byte) '0', (byte) '1', (byte) '2', (byte) '3', (byte) '4', (byte) '5', (byte) '6', (byte) '7', (byte) '8', (byte) '9', (byte) 'A', (byte) 'B', (byte) 'C', (byte) 'D', (byte) 'E', (byte) 'F', (byte) 'G', (byte) 'H', (byte) 'I', (byte) 'J', (byte) 'K', (byte) 'L', (byte) 'M', (byte) 'N', (byte) 'O', (byte) 'P', (byte) 'Q', (byte) 'R', (byte) 'S', (byte) 'T', (byte) 'U', (byte) 'V', (byte) 'W', (byte) 'X', (byte) 'Y', (byte) 'Z', (byte) '_', (byte) 'a', (byte) 'b', (byte) 'c', (byte) 'd', (byte) 'e', (byte) 'f', (byte) 'g', (byte) 'h', (byte) 'i', (byte) 'j', (byte) 'k', (byte) 'l', (byte) 'm', (byte) 'n', (byte) 'o', (byte) 'p', (byte) 'q', (byte) 'r', (byte) 's', (byte) 't', (byte) 'u', (byte) 'v', (byte) 'w', (byte) 'x', (byte) 'y', (byte) 'z' }; /** * Used in decoding the "ordered" dialect of Base64. */ private final static byte[] _ORDERED_DECODABET = { -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 0 - 8 -5, -5, // Whitespace: Tab and Linefeed -9, -9, // Decimal 11 - 12 -5, // Whitespace: Carriage Return -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 14 - 26 -9, -9, -9, -9, -9, // Decimal 27 - 31 -5, // Whitespace: Space -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 33 - 42 -9, // Plus sign at decimal 43 -9, // Decimal 44 0, // Minus sign at decimal 45 -9, // Decimal 46 -9, // Slash at decimal 47 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, // Numbers zero through nine -9, -9, -9, // Decimal 58 - 60 -1, // Equals sign at decimal 61 -9, -9, -9, // Decimal 62 - 64 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, // Letters 'A' through 'M' 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, // Letters 'N' through 'Z' -9, -9, -9, -9, // Decimal 91 - 94 37, // Underscore at decimal 95 -9, // Decimal 96 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, // Letters 'a' through 'm' 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, // Letters 'n' through 'z' -9, -9, -9, -9, -9 // Decimal 123 - 127 , -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 128 - 139 -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 140 - 152 -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 153 - 165 -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 166 - 178 -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 179 - 191 -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 192 - 204 -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 205 - 217 -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 218 - 230 -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 231 - 243 -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9 // Decimal 244 - 255 }; public static byte[] decode(byte[] bytes) { return decode(bytes, 0, bytes.length, NO_OPTIONS); } public static byte[] encode(byte[] bytes) { return encodeBytesToBytes(bytes, 0, bytes.length, NO_OPTIONS); } public static boolean isBase64(byte[] bytes) { try { decode(bytes); } catch (InvalidBase64CharacterException e) { return false; } return true; } /** * Returns one of the _SOMETHING_ALPHABET byte arrays depending on the options * specified. It's possible, though silly, to specify ORDERED <b>and</b> URLSAFE in * which case one of them will be picked, though there is no guarantee as to which one * will be picked. */ private static byte[] getAlphabet(int options) { if ((options & URL_SAFE) == URL_SAFE) { return _URL_SAFE_ALPHABET; } else if ((options & ORDERED) == ORDERED) { return _ORDERED_ALPHABET; } else { return _STANDARD_ALPHABET; } } /** * Returns one of the _SOMETHING_DECODABET byte arrays depending on the options * specified. It's possible, though silly, to specify ORDERED and URL_SAFE in which * case one of them will be picked, though there is no guarantee as to which one will * be picked. */ private static byte[] getDecodabet(int options) { if ((options & URL_SAFE) == URL_SAFE) { return _URL_SAFE_DECODABET; } else if ((options & ORDERED) == ORDERED) { return _ORDERED_DECODABET; } else { return _STANDARD_DECODABET; } } /* ******** E N C O D I N G M E T H O D S ******** */ /** * <p> * Encodes up to three bytes of the array <var>source</var> and writes the resulting * four Base64 bytes to <var>destination</var>. The source and destination arrays can * be manipulated anywhere along their length by specifying <var>srcOffset</var> and * <var>destOffset</var>. This method does not check to make sure your arrays are * large enough to accomodate <var>srcOffset</var> + 3 for the <var>source</var> array * or <var>destOffset</var> + 4 for the <var>destination</var> array. The actual * number of significant bytes in your array is given by <var>numSigBytes</var>. * </p> * <p> * This is the lowest level of the encoding methods with all possible parameters. * </p> * * @param source the array to convert * @param srcOffset the index where conversion begins * @param numSigBytes the number of significant bytes in your array * @param destination the array to hold the conversion * @param destOffset the index where output will be put * @return the <var>destination</var> array * @since 1.3 */ private static byte[] encode3to4(byte[] source, int srcOffset, int numSigBytes, byte[] destination, int destOffset, int options) { byte[] ALPHABET = getAlphabet(options); // 1 2 3 // 01234567890123456789012345678901 Bit position // --------000000001111111122222222 Array position from threeBytes // --------| || || || | Six bit groups to index ALPHABET // >>18 >>12 >> 6 >> 0 Right shift necessary // 0x3f 0x3f 0x3f Additional AND // Create buffer with zero-padding if there are only one or two // significant bytes passed in the array. // We have to shift left 24 in order to flush out the 1's that appear // when Java treats a value as negative that is cast from a byte to an int. int inBuff = (numSigBytes > 0 ? ((source[srcOffset] << 24) >>> 8) : 0) | (numSigBytes > 1 ? ((source[srcOffset + 1] << 24) >>> 16) : 0) | (numSigBytes > 2 ? ((source[srcOffset + 2] << 24) >>> 24) : 0); switch (numSigBytes) { case 3: destination[destOffset] = ALPHABET[(inBuff >>> 18)]; destination[destOffset + 1] = ALPHABET[(inBuff >>> 12) & 0x3f]; destination[destOffset + 2] = ALPHABET[(inBuff >>> 6) & 0x3f]; destination[destOffset + 3] = ALPHABET[(inBuff) & 0x3f]; return destination; case 2: destination[destOffset] = ALPHABET[(inBuff >>> 18)]; destination[destOffset + 1] = ALPHABET[(inBuff >>> 12) & 0x3f]; destination[destOffset + 2] = ALPHABET[(inBuff >>> 6) & 0x3f]; destination[destOffset + 3] = EQUALS_SIGN; return destination; case 1: destination[destOffset] = ALPHABET[(inBuff >>> 18)]; destination[destOffset + 1] = ALPHABET[(inBuff >>> 12) & 0x3f]; destination[destOffset + 2] = EQUALS_SIGN; destination[destOffset + 3] = EQUALS_SIGN; return destination; default: return destination; } } /** * * @param source The data to convert * @param off Offset in array where conversion should begin * @param len Length of data to convert * @param options Specified options * @return The Base64-encoded data as a String * @see Base64#DO_BREAK_LINES * @throws java.io.IOException if there is an error * @throws NullPointerException if source array is null * @throws IllegalArgumentException if source array, offset, or length are invalid * @since 2.3.1 */ private static byte[] encodeBytesToBytes(byte[] source, int off, int len, int options) { if (source == null) { throw new NullPointerException("Cannot serialize a null array."); } // end if: null if (off < 0) { throw new IllegalArgumentException("Cannot have negative offset: " + off); } // end if: off < 0 if (len < 0) { throw new IllegalArgumentException("Cannot have length offset: " + len); } // end if: len < 0 if (off + len > source.length) { throw new IllegalArgumentException(String.format( "Cannot have offset of %d and length of %d with array of length %d", off, len, source.length)); } // end if: off < 0 boolean breakLines = (options & DO_BREAK_LINES) > 0; // int len43 = len * 4 / 3; // byte[] outBuff = new byte[ ( len43 ) // Main 4:3 // + ( (len % 3) > 0 ? 4 : 0 ) // Account for padding // + (breakLines ? ( len43 / MAX_LINE_LENGTH ) : 0) ]; // New lines // Try to determine more precisely how big the array needs to be. // If we get it right, we don't have to do an array copy, and // we save a bunch of memory. int encLen = (len / 3) * 4 + (len % 3 > 0 ? 4 : 0); // Bytes needed for actual // encoding if (breakLines) { encLen += encLen / MAX_LINE_LENGTH; // Plus extra newline characters } byte[] outBuff = new byte[encLen]; int d = 0; int e = 0; int len2 = len - 2; int lineLength = 0; for (; d < len2; d += 3, e += 4) { encode3to4(source, d + off, 3, outBuff, e, options); lineLength += 4; if (breakLines && lineLength >= MAX_LINE_LENGTH) { outBuff[e + 4] = NEW_LINE; e++; lineLength = 0; } // end if: end of line } // en dfor: each piece of array if (d < len) { encode3to4(source, d + off, len - d, outBuff, e, options); e += 4; } // end if: some padding needed // Only resize array if we didn't guess it right. if (e <= outBuff.length - 1) { byte[] finalOut = new byte[e]; System.arraycopy(outBuff, 0, finalOut, 0, e); // System.err.println("Having to resize array from " + outBuff.length + " to " // + e ); return finalOut; } else { // System.err.println("No need to resize array."); return outBuff; } } /* ******** D E C O D I N G M E T H O D S ******** */ /** * Decodes four bytes from array <var>source</var> and writes the resulting bytes (up * to three of them) to <var>destination</var>. The source and destination arrays can * be manipulated anywhere along their length by specifying <var>srcOffset</var> and * <var>destOffset</var>. This method does not check to make sure your arrays are * large enough to accomodate <var>srcOffset</var> + 4 for the <var>source</var> array * or <var>destOffset</var> + 3 for the <var>destination</var> array. This method * returns the actual number of bytes that were converted from the Base64 encoding. * <p> * This is the lowest level of the decoding methods with all possible parameters. * </p> * * * @param source the array to convert * @param srcOffset the index where conversion begins * @param destination the array to hold the conversion * @param destOffset the index where output will be put * @param options alphabet type is pulled from this (standard, url-safe, ordered) * @return the number of decoded bytes converted * @throws NullPointerException if source or destination arrays are null * @throws IllegalArgumentException if srcOffset or destOffset are invalid or there is * not enough room in the array. * @since 1.3 */ private static int decode4to3(final byte[] source, final int srcOffset, final byte[] destination, final int destOffset, final int options) { // Lots of error checking and exception throwing if (source == null) { throw new NullPointerException("Source array was null."); } // end if if (destination == null) { throw new NullPointerException("Destination array was null."); } // end if if (srcOffset < 0 || srcOffset + 3 >= source.length) { throw new IllegalArgumentException(String.format( "Source array with length %d cannot have offset of %d and still process four bytes.", source.length, srcOffset)); } // end if if (destOffset < 0 || destOffset + 2 >= destination.length) { throw new IllegalArgumentException(String.format( "Destination array with length %d cannot have offset of %d and still store three bytes.", destination.length, destOffset)); } // end if byte[] DECODABET = getDecodabet(options); // Example: Dk== if (source[srcOffset + 2] == EQUALS_SIGN) { // Two ways to do the same thing. Don't know which way I like best. // int outBuff = ( ( DECODABET[ source[ srcOffset ] ] << 24 ) >>> 6 ) // | ( ( DECODABET[ source[ srcOffset + 1] ] << 24 ) >>> 12 ); int outBuff = ((DECODABET[source[srcOffset]] & 0xFF) << 18) | ((DECODABET[source[srcOffset + 1]] & 0xFF) << 12); destination[destOffset] = (byte) (outBuff >>> 16); return 1; } // Example: DkL= else if (source[srcOffset + 3] == EQUALS_SIGN) { // Two ways to do the same thing. Don't know which way I like best. // int outBuff = ( ( DECODABET[ source[ srcOffset ] ] << 24 ) >>> 6 ) // | ( ( DECODABET[ source[ srcOffset + 1 ] ] << 24 ) >>> 12 ) // | ( ( DECODABET[ source[ srcOffset + 2 ] ] << 24 ) >>> 18 ); int outBuff = ((DECODABET[source[srcOffset]] & 0xFF) << 18) | ((DECODABET[source[srcOffset + 1]] & 0xFF) << 12) | ((DECODABET[source[srcOffset + 2]] & 0xFF) << 6); destination[destOffset] = (byte) (outBuff >>> 16); destination[destOffset + 1] = (byte) (outBuff >>> 8); return 2; } // Example: DkLE else { // Two ways to do the same thing. Don't know which way I like best. // int outBuff = ( ( DECODABET[ source[ srcOffset ] ] << 24 ) >>> 6 ) // | ( ( DECODABET[ source[ srcOffset + 1 ] ] << 24 ) >>> 12 ) // | ( ( DECODABET[ source[ srcOffset + 2 ] ] << 24 ) >>> 18 ) // | ( ( DECODABET[ source[ srcOffset + 3 ] ] << 24 ) >>> 24 ); int outBuff = ((DECODABET[source[srcOffset]] & 0xFF) << 18) | ((DECODABET[source[srcOffset + 1]] & 0xFF) << 12) | ((DECODABET[source[srcOffset + 2]] & 0xFF) << 6) | ((DECODABET[source[srcOffset + 3]] & 0xFF)); destination[destOffset] = (byte) (outBuff >> 16); destination[destOffset + 1] = (byte) (outBuff >> 8); destination[destOffset + 2] = (byte) (outBuff); return 3; } } /** * Low-level access to decoding ASCII characters in the form of a byte array. * <strong>Ignores GUNZIP option, if it's set.</strong> This is not generally a * recommended method, although it is used internally as part of the decoding process. * Special case: if len = 0, an empty array is returned. Still, if you need more speed * and reduced memory footprint (and aren't gzipping), consider this method. * * @param source The Base64 encoded data * @param off The offset of where to begin decoding * @param len The length of characters to decode * @param options Can specify options such as alphabet type to use * @return decoded data * @throws IllegalArgumentException If bogus characters exist in source data */ private static byte[] decode(final byte[] source, final int off, final int len, final int options) { // Lots of error checking and exception throwing if (source == null) { throw new NullPointerException("Cannot decode null source array."); } // end if if (off < 0 || off + len > source.length) { throw new IllegalArgumentException( String.format("Source array with length %d cannot have offset of %d and process %d bytes.", source.length, off, len)); } // end if if (len == 0) { return new byte[0]; } else if (len < 4) { throw new IllegalArgumentException( "Base64-encoded string must have at least four characters, but length specified was " + len); } // end if byte[] DECODABET = getDecodabet(options); int len34 = len * 3 / 4; // Estimate on array size byte[] outBuff = new byte[len34]; // Upper limit on size of output int outBuffPosn = 0; // Keep track of where we're writing byte[] b4 = new byte[4]; // Four byte buffer from source, eliminating white space int b4Posn = 0; // Keep track of four byte input buffer int i = 0; // Source array counter byte sbiDecode = 0; // Special value from DECODABET for (i = off; i < off + len; i++) { // Loop through source sbiDecode = DECODABET[source[i] & 0xFF]; // White space, Equals sign, or legit Base64 character // Note the values such as -5 and -9 in the // DECODABETs at the top of the file. if (sbiDecode >= WHITE_SPACE_ENC) { if (sbiDecode >= EQUALS_SIGN_ENC) { b4[b4Posn++] = source[i]; // Save non-whitespace if (b4Posn > 3) { // Time to decode? outBuffPosn += decode4to3(b4, 0, outBuff, outBuffPosn, options); b4Posn = 0; // If that was the equals sign, break out of 'for' loop if (source[i] == EQUALS_SIGN) { break; } } } } else { // There's a bad input character in the Base64 stream. throw new InvalidBase64CharacterException(String.format( "Bad Base64 input character decimal %d in array position %d", ((int) source[i]) & 0xFF, i)); } } byte[] out = new byte[outBuffPosn]; System.arraycopy(outBuff, 0, out, 0, outBuffPosn); return out; } } class InvalidBase64CharacterException extends IllegalArgumentException { InvalidBase64CharacterException(String message) { super(message); } }