org.springframework.webflow.util.Base64 Maven / Gradle / Ivy
/*
* Copyright 2004-2007 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
*
* 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.springframework.webflow.util;
/**
* Encodes and decodes to and from Base64 notation.
*
* Based on Base64 encoder and decoder version 2.2.1 written by Robert Harder
* (http://iharder.net/base64).
* Modified by Erwin Vervaet to use the '.' character as padding character
* when using URL safe encoding, like in the Bouncy Castle URLBase64 encoder
* (http://www.bouncycastle.org/java.html).
*
* @author Robert Harder
* @author Erwin Vervaet
*/
public class Base64 {
/* static data used by the encoding and decoding algorithm
/* The equals sign (=) as a byte. */
private static final byte EQUALS_SIGN = (byte)'=';
/* The dot (.) as a byte. */
private static final byte DOT = (byte)'.';
private static final byte WHITE_SPACE_ENC = -5; // Indicates white space in encoding
private static final byte PADDING_CHAR_ENC = -1; // Indicates padding char 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 may be something funny like EBCDIC, so we hardcode these values. */
private static final 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 static final 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 // Decimal 123 - 126
};
/* ******** 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:
* http://www.faqs.org/rfcs/rfc3548.html.
* Notice that the last two bytes become "hyphen" and "underscore" instead of "plus" and "slash."
*/
private static final 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 static final 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
-1, // Dot at 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
-9, // 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 // Decimal 123 - 126
};
// instance members
/**
* Encode using Base64-like encoding that is URL- and Filename-safe as described
* in Section 4 of RFC3548:
* http://www.faqs.org/rfcs/rfc3548.html.
*/
private boolean urlSafe;
private byte[] ALPHABET;
private byte[] DECODABET;
private byte PADDING_CHAR;
/**
* Create a new Base64 encoder and decoder using the standard Base64 alphabet.
* Note that the resulting encoded strings are not URL-safe: they will
* can contain characters that are subject to URL encoding.
*/
public Base64() {
this(false);
}
/**
* Create a new Base64 encoder and decoder.
*
Allows Base64-like encoding that is URL- and Filename-safe as described
* in Section 4 of RFC3548:
* http://www.faqs.org/rfcs/rfc3548.html.
* When URL-safe encoding is used, the standard "=" Base64 padding character is replaced
* with the '.' character.
*
* It is important to note that data encoded this way is not 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
*
* @param urlSafe if true, URL safe encoding and decoding will be used
*/
public Base64(boolean urlSafe) {
this.urlSafe = urlSafe;
if (urlSafe) {
ALPHABET = URL_SAFE_ALPHABET;
DECODABET = URL_SAFE_DECODABET;
PADDING_CHAR = DOT;
}
else {
ALPHABET = STANDARD_ALPHABET;
DECODABET = STANDARD_DECODABET;
PADDING_CHAR = EQUALS_SIGN;
}
}
/**
* Returns whether or not this coder is using Base64-like encoding that is URL- and Filename-safe
* as described in Section 4 of RFC3548:
* http://www.faqs.org/rfcs/rfc3548.html.
* When URL-safe encoding is used, the standard "=" Base64 padding character is replaced
* with the '.' character.
*
* It is important to note that data encoded this way is not 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.
* @return true or false
*/
public boolean isUrlSafe() {
return urlSafe;
}
/* ******** 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 accomodate 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.
* This is the lowest level of the encoding methods with
* all possible parameters.
* @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 destination array
*/
private byte[] encode3to4(byte[] source, int srcOffset, int numSigBytes, byte[] destination, int destOffset) {
// 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 ] = PADDING_CHAR;
return destination;
case 1:
destination[ destOffset ] = ALPHABET[ (inBuff >>> 18) ];
destination[ destOffset + 1 ] = ALPHABET[ (inBuff >>> 12) & 0x3f ];
destination[ destOffset + 2 ] = PADDING_CHAR;
destination[ destOffset + 3 ] = PADDING_CHAR;
return destination;
default:
return destination;
}
}
/**
* 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
* @return the encoded data
*/
public final byte[] encode(byte[] source, int off, int len) {
int len43 = len * 4 / 3;
byte[] outBuff = new byte[ ( len43 ) // main 4:3
+ ( (len % 3) > 0 ? 4 : 0 ) ]; // account for padding
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);
lineLength += 4;
} // end for: each piece of array
if (d < len) {
encode3to4(source, d+off, len - d, outBuff, e);
e += 4;
} // end if: some padding needed
byte[] out = new byte[e];
System.arraycopy(outBuff, 0, out, 0, e);
return out;
}
/**
* Encodes a byte array into Base64 notation.
* @param source the data to encode
* @return the encoded data
*/
public final byte[] encode(byte[] source) {
return encode(source, 0, source.length);
}
/**
* Encodes a byte array into Base64 notation. The resulting string will
* be created using the platform default encoding.
* @param source the source data to encode
* @return the encoded data
*/
public final String encodeToString(byte[] source) {
return new String(encode(source));
}
/* ******** 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 accomodate 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.
* This is the lowest level of the decoding methods with
* all possible parameters.
* @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
* @return the number of decoded bytes converted
*/
private final int decode4to3(byte[] source, int srcOffset, byte[] destination, int destOffset) {
// Example: Dk== or Dk..
if (source[ srcOffset + 2] == PADDING_CHAR) {
int outBuff = ( ( DECODABET[ source[ srcOffset ] ] & 0xFF ) << 18 )
| ( ( DECODABET[ source[ srcOffset + 1] ] & 0xFF ) << 12 );
destination[ destOffset ] = (byte)( outBuff >>> 16 );
return 1;
}
// Example: DkL= or DkL.
else if (source[ srcOffset + 3 ] == PADDING_CHAR) {
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 {
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;
}
}
/**
* Very low-level access to decoding ASCII characters in
* the form of a 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
*/
public final byte[] decode(byte[] source, int off, int len) {
int len34 = len * 3 / 4;
byte[] outBuff = new byte[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 = off; i < off + len; i++) {
sbiCrop = (byte)(source[i] & 0x7f); // only the low seven bits
sbiDecode = DECODABET[sbiCrop];
if (sbiDecode >= WHITE_SPACE_ENC) { // white space, equals sign or better
if (sbiDecode >= PADDING_CHAR_ENC) {
b4[b4Posn++] = sbiCrop;
if (b4Posn > 3) {
outBuffPosn += decode4to3(b4, 0, outBuff, outBuffPosn);
b4Posn = 0;
// if that was the padding char, break out of 'for' loop
if (sbiCrop == PADDING_CHAR) {
break;
}
} // end if: quartet built
} // end if: equals sign or better
} // end if: white space, equals sign or better
else {
//discard
}
} // each input character
byte[] out = new byte[outBuffPosn];
System.arraycopy(outBuff, 0, out, 0, outBuffPosn);
return out;
}
/**
* Decodes data from Base64 notation.
* @param source the source data
* @return the decoded data
*/
public final byte[] decode(byte[] source) {
return decode(source, 0, source.length);
}
/**
* Decodes data from Base64 notation. Uses the platform default
* character set to obtain bytes from given string.
* @param s the string to decode
* @return the decoded data
*/
public final byte[] decodeFromString(String s) {
return decode(s.getBytes());
}
}