// | |
// NOTE: The following source code is heavily derived from the | |
// iHarder.net public domain Base64 library. See the original at | |
// http://iharder.sourceforge.net/current/java/base64/ | |
// | |
package com.gitblit.utils; | |
import java.io.UnsupportedEncodingException; | |
import java.text.MessageFormat; | |
import java.util.Arrays; | |
/** | |
* Encodes and decodes to and from Base64 notation. | |
* <p> | |
* 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 <a | |
* href="http://iharder.net/base64">http://iharder.net/base64</a> periodically | |
* to check for updates or to contribute improvements. | |
* </p> | |
* | |
* @author Robert Harder | |
* @author rob@iharder.net | |
* @version 2.1, stripped to minimum feature set used by JGit. | |
*/ | |
public class Base64 { | |
/** The equals sign (=) as a byte. */ | |
private final static byte EQUALS_SIGN = (byte) '='; | |
/** Indicates equals sign in encoding. */ | |
private final static byte EQUALS_SIGN_DEC = -1; | |
/** Indicates white space in encoding. */ | |
private final static byte WHITE_SPACE_DEC = -2; | |
/** Indicates an invalid byte during decoding. */ | |
private final static byte INVALID_DEC = -3; | |
/** Preferred encoding. */ | |
private final static String UTF_8 = "UTF-8"; | |
/** The 64 valid Base64 values. */ | |
private final static byte[] ENC; | |
/** | |
* Translates a Base64 value to either its 6-bit reconstruction value or a | |
* negative number indicating some other meaning. The table is only 7 bits | |
* wide, as the 8th bit is discarded during decoding. | |
*/ | |
private final static byte[] DEC; | |
static { | |
try { | |
ENC = ("ABCDEFGHIJKLMNOPQRSTUVWXYZ" // | |
+ "abcdefghijklmnopqrstuvwxyz" // | |
+ "0123456789" // | |
+ "+/" // | |
).getBytes(UTF_8); | |
} catch (UnsupportedEncodingException uee) { | |
throw new RuntimeException(uee.getMessage(), uee); | |
} | |
DEC = new byte[128]; | |
Arrays.fill(DEC, INVALID_DEC); | |
for (int i = 0; i < 64; i++) | |
DEC[ENC[i]] = (byte) i; | |
DEC[EQUALS_SIGN] = EQUALS_SIGN_DEC; | |
DEC['\t'] = WHITE_SPACE_DEC; | |
DEC['\n'] = WHITE_SPACE_DEC; | |
DEC['\r'] = WHITE_SPACE_DEC; | |
DEC[' '] = WHITE_SPACE_DEC; | |
} | |
/** Defeats instantiation. */ | |
private Base64() { | |
// Suppress empty block warning. | |
} | |
/** | |
* 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 accommodate | |
* <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>. | |
* | |
* @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 | |
*/ | |
private static void encode3to4(byte[] source, int srcOffset, int numSigBytes, | |
byte[] destination, int destOffset) { | |
// 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. | |
int inBuff = 0; | |
switch (numSigBytes) { | |
case 3: | |
inBuff |= (source[srcOffset + 2] << 24) >>> 24; | |
//$FALL-THROUGH$ | |
case 2: | |
inBuff |= (source[srcOffset + 1] << 24) >>> 16; | |
//$FALL-THROUGH$ | |
case 1: | |
inBuff |= (source[srcOffset] << 24) >>> 8; | |
} | |
switch (numSigBytes) { | |
case 3: | |
destination[destOffset] = ENC[(inBuff >>> 18)]; | |
destination[destOffset + 1] = ENC[(inBuff >>> 12) & 0x3f]; | |
destination[destOffset + 2] = ENC[(inBuff >>> 6) & 0x3f]; | |
destination[destOffset + 3] = ENC[(inBuff) & 0x3f]; | |
break; | |
case 2: | |
destination[destOffset] = ENC[(inBuff >>> 18)]; | |
destination[destOffset + 1] = ENC[(inBuff >>> 12) & 0x3f]; | |
destination[destOffset + 2] = ENC[(inBuff >>> 6) & 0x3f]; | |
destination[destOffset + 3] = EQUALS_SIGN; | |
break; | |
case 1: | |
destination[destOffset] = ENC[(inBuff >>> 18)]; | |
destination[destOffset + 1] = ENC[(inBuff >>> 12) & 0x3f]; | |
destination[destOffset + 2] = EQUALS_SIGN; | |
destination[destOffset + 3] = EQUALS_SIGN; | |
break; | |
} | |
} | |
/** | |
* Encodes a byte array into Base64 notation. | |
* | |
* @param source | |
* The data to convert | |
* @return encoded base64 representation of source. | |
*/ | |
public static String encodeBytes(byte[] source) { | |
return encodeBytes(source, 0, source.length); | |
} | |
/** | |
* 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 encoded base64 representation of source. | |
*/ | |
public static String encodeBytes(byte[] source, int off, int len) { | |
final int len43 = len * 4 / 3; | |
byte[] outBuff = new byte[len43 + ((len % 3) > 0 ? 4 : 0)]; | |
int d = 0; | |
int e = 0; | |
int len2 = len - 2; | |
for (; d < len2; d += 3, e += 4) | |
encode3to4(source, d + off, 3, outBuff, e); | |
if (d < len) { | |
encode3to4(source, d + off, len - d, outBuff, e); | |
e += 4; | |
} | |
try { | |
return new String(outBuff, 0, e, UTF_8); | |
} catch (UnsupportedEncodingException uue) { | |
return new String(outBuff, 0, e); | |
} | |
} | |
/** | |
* 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 accommodate | |
* <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. | |
* | |
* @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 static int decode4to3(byte[] source, int srcOffset, byte[] destination, int destOffset) { | |
// Example: Dk== | |
if (source[srcOffset + 2] == EQUALS_SIGN) { | |
int outBuff = ((DEC[source[srcOffset]] & 0xFF) << 18) | |
| ((DEC[source[srcOffset + 1]] & 0xFF) << 12); | |
destination[destOffset] = (byte) (outBuff >>> 16); | |
return 1; | |
} | |
// Example: DkL= | |
else if (source[srcOffset + 3] == EQUALS_SIGN) { | |
int outBuff = ((DEC[source[srcOffset]] & 0xFF) << 18) | |
| ((DEC[source[srcOffset + 1]] & 0xFF) << 12) | |
| ((DEC[source[srcOffset + 2]] & 0xFF) << 6); | |
destination[destOffset] = (byte) (outBuff >>> 16); | |
destination[destOffset + 1] = (byte) (outBuff >>> 8); | |
return 2; | |
} | |
// Example: DkLE | |
else { | |
int outBuff = ((DEC[source[srcOffset]] & 0xFF) << 18) | |
| ((DEC[source[srcOffset + 1]] & 0xFF) << 12) | |
| ((DEC[source[srcOffset + 2]] & 0xFF) << 6) | |
| ((DEC[source[srcOffset + 3]] & 0xFF)); | |
destination[destOffset] = (byte) (outBuff >> 16); | |
destination[destOffset + 1] = (byte) (outBuff >> 8); | |
destination[destOffset + 2] = (byte) (outBuff); | |
return 3; | |
} | |
} | |
/** | |
* Low-level decoding ASCII characters from 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 | |
* @throws IllegalArgumentException | |
* the input is not a valid Base64 sequence. | |
*/ | |
public static byte[] decode(byte[] source, int off, int len) { | |
byte[] outBuff = new byte[len * 3 / 4]; // Upper limit on size of output | |
int outBuffPosn = 0; | |
byte[] b4 = new byte[4]; | |
int b4Posn = 0; | |
for (int i = off; i < off + len; i++) { | |
byte sbiCrop = (byte) (source[i] & 0x7f); | |
byte sbiDecode = DEC[sbiCrop]; | |
if (EQUALS_SIGN_DEC <= sbiDecode) { | |
b4[b4Posn++] = sbiCrop; | |
if (b4Posn > 3) { | |
outBuffPosn += decode4to3(b4, 0, outBuff, outBuffPosn); | |
b4Posn = 0; | |
// If that was the equals sign, break out of 'for' loop | |
if (sbiCrop == EQUALS_SIGN) | |
break; | |
} | |
} else if (sbiDecode != WHITE_SPACE_DEC) | |
throw new IllegalArgumentException(MessageFormat.format( | |
"bad base64 input character {1} at {0}", i, source[i] & 0xff)); | |
} | |
if (outBuff.length == outBuffPosn) | |
return outBuff; | |
byte[] out = new byte[outBuffPosn]; | |
System.arraycopy(outBuff, 0, out, 0, outBuffPosn); | |
return out; | |
} | |
/** | |
* Decodes data from Base64 notation. | |
* | |
* @param s | |
* the string to decode | |
* @return the decoded data | |
*/ | |
public static byte[] decode(String s) { | |
byte[] bytes; | |
try { | |
bytes = s.getBytes(UTF_8); | |
} catch (UnsupportedEncodingException uee) { | |
bytes = s.getBytes(); | |
} | |
return decode(bytes, 0, bytes.length); | |
} | |
} |