+ * I am placing this code in the Public Domain. Do with it as you will. + * This software comes with no guarantees or warranties but with + * plenty of well-wishing instead! + * Please visit + * http://iharder.net/xmlizable + * periodically to check for updates or to contribute improvements. + *
+ * + * @author Robert Harder + * @author rharder@usa.net + * @version 1.3 + */ + +/** + * Base64 converter class. This code is not a full-blown MIME encoder; + * it simply converts binary data to base64 data and back. + * + *Note {@link CharBase64} is a GWT-compatible implementation of this + * class. + */ +public class Base64 { + /** Specify encoding (value is {@code true}). */ + public final static boolean ENCODE = true; + + /** Specify decoding (value is {@code false}). */ + public final static boolean DECODE = false; + + /** 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'; + + /** + * The 64 valid Base64 values. + */ + private final static byte[] 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) '/'}; + + /** + * The 64 valid web safe Base64 values. + */ + private final static byte[] WEBSAFE_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[] 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 */ + }; + + /** The web safe decodabet */ + private final static byte[] WEBSAFE_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, -9, -9, // Decimal 33 - 44 + 62, // Dash '-' sign at decimal 45 + -9, -9, // Decimal 46-47 + 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 */ + }; + + // Indicates white space in encoding + private final static byte WHITE_SPACE_ENC = -5; + // Indicates equals sign in encoding + private final static byte EQUALS_SIGN_ENC = -1; + + /** Defeats instantiation. */ + private Base64() { + } + + /* ******** E N C O D I N G M E T H O D S ******** */ + + /** + * Encodes up to three bytes of the array source + * and writes the resulting four Base64 bytes to destination. + * The source and destination arrays can be manipulated + * anywhere along their length by specifying + * srcOffset and destOffset. + * This method does not check to make sure your arrays + * are large enough to accommodate srcOffset + 3 for + * the source array or destOffset + 4 for + * the destination array. + * The actual number of significant bytes in your array is + * given by numSigBytes. + * + * @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 + * @param alphabet is the encoding alphabet + * @return the destination array + * @since 1.3 + */ + private static byte[] encode3to4(byte[] source, int srcOffset, + int numSigBytes, byte[] destination, int destOffset, byte[] alphabet) { + // 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; + } // end switch + } // end encode3to4 + + /** + * Encodes a byte array into Base64 notation. + * Equivalent to calling + * {@code encodeBytes(source, 0, source.length)} + * + * @param source The data to convert + * @since 1.4 + */ + public static String encode(byte[] source) { + return encode(source, 0, source.length, ALPHABET, true); + } + + /** + * Encodes a byte array into web safe Base64 notation. + * + * @param source The data to convert + * @param doPadding is {@code true} to pad result with '=' chars + * if it does not fall on 3 byte boundaries + */ + public static String encodeWebSafe(byte[] source, boolean doPadding) { + return encode(source, 0, source.length, WEBSAFE_ALPHABET, doPadding); + } + + /** + * Encodes a byte array into Base64 notation. + * + * @param source The data to convert + * @param off Offset in array where conversion should begin + * @param len Length of data to convert + * @param alphabet is the encoding alphabet + * @param doPadding is {@code true} to pad result with '=' chars + * if it does not fall on 3 byte boundaries + * @since 1.4 + */ + public static String encode(byte[] source, int off, int len, byte[] alphabet, + boolean doPadding) { + byte[] outBuff = encode(source, off, len, alphabet, Integer.MAX_VALUE); + int outLen = outBuff.length; + + // If doPadding is false, set length to truncate '=' + // padding characters + while (doPadding == false && outLen > 0) { + if (outBuff[outLen - 1] != '=') { + break; + } + outLen -= 1; + } + + return new String(outBuff, 0, outLen); + } + + /** + * Encodes a byte array into Base64 notation. + * + * @param source The data to convert + * @param off Offset in array where conversion should begin + * @param len Length of data to convert + * @param alphabet is the encoding alphabet + * @param maxLineLength maximum length of one line. + * @return the BASE64-encoded byte array + */ + public static byte[] encode(byte[] source, int off, int len, byte[] alphabet, + int maxLineLength) { + int lenDiv3 = (len + 2) / 3; // ceil(len / 3) + int len43 = lenDiv3 * 4; + byte[] outBuff = new byte[len43 // Main 4:3 + + (len43 / maxLineLength)]; // New lines + + int d = 0; + int e = 0; + int len2 = len - 2; + int lineLength = 0; + for (; d < len2; d += 3, e += 4) { + + // The following block of code is the same as + // encode3to4( source, d + off, 3, outBuff, e, alphabet ); + // but inlined for faster encoding (~20% improvement) + int inBuff = + ((source[d + off] << 24) >>> 8) + | ((source[d + 1 + off] << 24) >>> 16) + | ((source[d + 2 + off] << 24) >>> 24); + outBuff[e] = alphabet[(inBuff >>> 18)]; + outBuff[e + 1] = alphabet[(inBuff >>> 12) & 0x3f]; + outBuff[e + 2] = alphabet[(inBuff >>> 6) & 0x3f]; + outBuff[e + 3] = alphabet[(inBuff) & 0x3f]; + + lineLength += 4; + if (lineLength == maxLineLength) { + outBuff[e + 4] = NEW_LINE; + e++; + lineLength = 0; + } // end if: end of line + } // end for: each piece of array + + if (d < len) { + encode3to4(source, d + off, len - d, outBuff, e, alphabet); + + lineLength += 4; + if (lineLength == maxLineLength) { + // Add a last newline + outBuff[e + 4] = NEW_LINE; + e++; + } + e += 4; + } + + assert (e == outBuff.length); + return outBuff; + } + + + /* ******** D E C O D I N G M E T H O D S ******** */ + + + /** + * Decodes four bytes from array source + * and writes the resulting bytes (up to three of them) + * to destination. + * The source and destination arrays can be manipulated + * anywhere along their length by specifying + * srcOffset and destOffset. + * This method does not check to make sure your arrays + * are large enough to accommodate srcOffset + 4 for + * the source array or destOffset + 3 for + * the destination array. + * This method returns the actual number of bytes that + * were converted from the Base64 encoding. + * + * + * @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 decodabet the decodabet for decoding Base64 content + * @return the number of decoded bytes converted + * @since 1.3 + */ + private static int decode4to3(byte[] source, int srcOffset, + byte[] destination, int destOffset, byte[] decodabet) { + // Example: Dk== + if (source[srcOffset + 2] == EQUALS_SIGN) { + int outBuff = + ((decodabet[source[srcOffset]] << 24) >>> 6) + | ((decodabet[source[srcOffset + 1]] << 24) >>> 12); + + destination[destOffset] = (byte) (outBuff >>> 16); + return 1; + } else if (source[srcOffset + 3] == EQUALS_SIGN) { + // Example: DkL= + int outBuff = + ((decodabet[source[srcOffset]] << 24) >>> 6) + | ((decodabet[source[srcOffset + 1]] << 24) >>> 12) + | ((decodabet[source[srcOffset + 2]] << 24) >>> 18); + + destination[destOffset] = (byte) (outBuff >>> 16); + destination[destOffset + 1] = (byte) (outBuff >>> 8); + return 2; + } else { + // Example: DkLE + 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); + + destination[destOffset] = (byte) (outBuff >> 16); + destination[destOffset + 1] = (byte) (outBuff >> 8); + destination[destOffset + 2] = (byte) (outBuff); + return 3; + } + } // end decodeToBytes + + + /** + * Decodes data from Base64 notation. + * + * @param s the string to decode (decoded in default encoding) + * @return the decoded data + * @since 1.4 + */ + public static byte[] decode(String s) throws Base64DecoderException { + byte[] bytes = s.getBytes(); + return decode(bytes, 0, bytes.length); + } + + /** + * Decodes data from web safe Base64 notation. + * Web safe encoding uses '-' instead of '+', '_' instead of '/' + * + * @param s the string to decode (decoded in default encoding) + * @return the decoded data + */ + public static byte[] decodeWebSafe(String s) throws Base64DecoderException { + byte[] bytes = s.getBytes(); + return decodeWebSafe(bytes, 0, bytes.length); + } + + /** + * Decodes Base64 content in byte array format and returns + * the decoded byte array. + * + * @param source The Base64 encoded data + * @return decoded data + * @since 1.3 + * @throws Base64DecoderException + */ + public static byte[] decode(byte[] source) throws Base64DecoderException { + return decode(source, 0, source.length); + } + + /** + * Decodes web safe Base64 content in byte array format and returns + * the decoded data. + * Web safe encoding uses '-' instead of '+', '_' instead of '/' + * + * @param source the string to decode (decoded in default encoding) + * @return the decoded data + */ + public static byte[] decodeWebSafe(byte[] source) + throws Base64DecoderException { + return decodeWebSafe(source, 0, source.length); + } + + /** + * Decodes Base64 content in byte array format and returns + * the decoded byte array. + * + * @param source The Base64 encoded data + * @param off The offset of where to begin decoding + * @param len The length of characters to decode + * @return decoded data + * @since 1.3 + * @throws Base64DecoderException + */ + public static byte[] decode(byte[] source, int off, int len) + throws Base64DecoderException { + return decode(source, off, len, DECODABET); + } + + /** + * Decodes web safe Base64 content in byte array format and returns + * the decoded byte array. + * Web safe encoding uses '-' instead of '+', '_' instead of '/' + * + * @param source The Base64 encoded data + * @param off The offset of where to begin decoding + * @param len The length of characters to decode + * @return decoded data + */ + public static byte[] decodeWebSafe(byte[] source, int off, int len) + throws Base64DecoderException { + return decode(source, off, len, WEBSAFE_DECODABET); + } + + /** + * Decodes Base64 content using the supplied decodabet and returns + * the decoded byte array. + * + * @param source The Base64 encoded data + * @param off The offset of where to begin decoding + * @param len The length of characters to decode + * @param decodabet the decodabet for decoding Base64 content + * @return decoded data + */ + public static byte[] decode(byte[] source, int off, int len, byte[] decodabet) + throws Base64DecoderException { + int len34 = len * 3 / 4; + byte[] outBuff = new byte[2 + len34]; // Upper limit on size of output + int outBuffPosn = 0; + + byte[] b4 = new byte[4]; + int b4Posn = 0; + int i = 0; + byte sbiCrop = 0; + byte sbiDecode = 0; + for (i = 0; i < len; i++) { + sbiCrop = (byte) (source[i + off] & 0x7f); // Only the low seven bits + sbiDecode = decodabet[sbiCrop]; + + if (sbiDecode >= WHITE_SPACE_ENC) { // White space Equals sign or better + if (sbiDecode >= EQUALS_SIGN_ENC) { + // An equals sign (for padding) must not occur at position 0 or 1 + // and must be the last byte[s] in the encoded value + if (sbiCrop == EQUALS_SIGN) { + int bytesLeft = len - i; + byte lastByte = (byte) (source[len - 1 + off] & 0x7f); + if (b4Posn == 0 || b4Posn == 1) { + throw new Base64DecoderException( + "invalid padding byte '=' at byte offset " + i); + } else if ((b4Posn == 3 && bytesLeft > 2) + || (b4Posn == 4 && bytesLeft > 1)) { + throw new Base64DecoderException( + "padding byte '=' falsely signals end of encoded value " + + "at offset " + i); + } else if (lastByte != EQUALS_SIGN && lastByte != NEW_LINE) { + throw new Base64DecoderException( + "encoded value has invalid trailing byte"); + } + break; + } + + b4[b4Posn++] = sbiCrop; + if (b4Posn == 4) { + outBuffPosn += decode4to3(b4, 0, outBuff, outBuffPosn, decodabet); + b4Posn = 0; + } + } + } else { + throw new Base64DecoderException("Bad Base64 input character at " + i + + ": " + source[i + off] + "(decimal)"); + } + } + + // Because web safe encoding allows non padding base64 encodes, we + // need to pad the rest of the b4 buffer with equal signs when + // b4Posn != 0. There can be at most 2 equal signs at the end of + // four characters, so the b4 buffer must have two or three + // characters. This also catches the case where the input is + // padded with EQUALS_SIGN + if (b4Posn != 0) { + if (b4Posn == 1) { + throw new Base64DecoderException("single trailing character at offset " + + (len - 1)); + } + b4[b4Posn++] = EQUALS_SIGN; + outBuffPosn += decode4to3(b4, 0, outBuff, outBuffPosn, decodabet); + } + + byte[] out = new byte[outBuffPosn]; + System.arraycopy(outBuff, 0, out, 0, outBuffPosn); + return out; + } +} \ No newline at end of file -- cgit v1.2.3