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/*******************************************************************************
* Copyright (c) 2004 Composent, Inc. and others. All rights reserved. This
* program and the accompanying materials are made available under the terms of
* the Eclipse Public License v1.0 which accompanies this distribution, and is
* available at http://www.eclipse.org/legal/epl-v10.html
*
* Contributors: Composent, Inc. - initial API and implementation
******************************************************************************/
package org.eclipse.ecf.core.util;
/**
*
* Encode/decode byte arrays into base64 strings. Code originally acquired from
* ftp://ftp.ora.com/pub/examples/java/crypto/files/oreilly/jonathan/util/
*
* Several small modifications were made: the '_' character was substituted for
* the '/' character, the '-' char substituted for the '=' char, and the '.'
* substituted for the '+' char so that the resulting string does not use any of
* the reserved characters in the URI reserved character set as described in
* RFC2396. See ftp://ftp.isi.edu/in-notes/rfc2396.txt for details.
*
*/
public final class Base64 {
/**
* Encode a byte array into a String
*
* @param raw
* the raw data to encode
* @return String that is base64 encoded
*/
public static String encode(byte[] raw) {
if (raw == null)
throw new NumberFormatException("Input data cannot be null");
StringBuffer encoded = new StringBuffer();
for (int i = 0; i < raw.length; i += 3) {
encoded.append(encodeBlock(raw, i));
}
return encoded.toString();
}
protected static char[] encodeBlock(byte[] raw, int offset) {
int block = 0;
int slack = raw.length - offset - 1;
int end = (slack >= 2) ? 2 : slack;
for (int i = 0; i <= end; i++) {
byte b = raw[offset + i];
int neuter = (b < 0) ? b + 256 : b;
block += neuter << (8 * (2 - i));
}
char[] base64 = new char[4];
for (int i = 0; i < 4; i++) {
int sixbit = (block >>> (6 * (3 - i))) & 0x3f;
base64[i] = getChar(sixbit);
}
// modify to use '-' instead of '='
if (slack < 1)
base64[2] = '-';
if (slack < 2)
base64[3] = '-';
return base64;
}
protected static char getChar(int sixBit) {
if (sixBit >= 0 && sixBit <= 25)
return (char) ('A' + sixBit);
if (sixBit >= 26 && sixBit <= 51)
return (char) ('a' + (sixBit - 26));
if (sixBit >= 52 && sixBit <= 61)
return (char) ('0' + (sixBit - 52));
if (sixBit == 62)
return '.';
// modify to use '_' instead of '/'
if (sixBit == 63)
return '_';
return '?';
}
/**
* Decode base64 string into a byte array.
*
* @param base64
* the base64 encoded string
* @return byte[] the resulting decoded data array
* @exception NumberFormatException
* thrown if String not in base64 format.
*/
public static byte[] decode(String base64) throws NumberFormatException {
int pad = 0;
for (int i = base64.length() - 1; base64.charAt(i) == '-'; i--)
pad++;
int length = base64.length() * 6 / 8 - pad;
byte[] raw = new byte[length];
int rawIndex = 0;
for (int i = 0; i < base64.length(); i += 4) {
int block = (getValue(base64.charAt(i)) << 18)
+ (getValue(base64.charAt(i + 1)) << 12)
+ (getValue(base64.charAt(i + 2)) << 6)
+ (getValue(base64.charAt(i + 3)));
for (int j = 0; j < 3 && rawIndex + j < raw.length; j++)
raw[rawIndex + j] = (byte) ((block >> (8 * (2 - j))) & 0xff);
rawIndex += 3;
}
return raw;
}
protected static int getValue(char c) throws NumberFormatException {
if (c >= 'A' && c <= 'Z')
return c - 'A';
if (c >= 'a' && c <= 'z')
return c - 'a' + 26;
if (c >= '0' && c <= '9')
return c - '0' + 52;
if (c == '.')
return 62;
// modify to use '_' instead of '/'
if (c == '_')
return 63;
// modify to use '-' instead of '='
if (c == '-')
return 0;
throw new NumberFormatException("Invalid value '" + c
+ "' in base64 string");
}
public static void main(String[] args) throws Exception {
System.out.println("Starting Base64 test program.");
int byteLength = 16;
java.security.SecureRandom ar = new java.security.SecureRandom();
byte[] buf = new byte[byteLength];
ar.nextBytes(buf);
System.out.println("Secure random bytes are:");
for (int i = 0; i < buf.length; i++)
System.out.print(buf[i] + " ");
System.out.println();
System.out.println("Converting secure random number to Base64...");
String res = Base64.encode(buf);
System.out.println("Converted string is: ");
System.out.println(res);
byte[] buf2 = new byte[byteLength];
System.out.println("Converting string back to byte array...");
buf2 = Base64.decode(res);
System.out.println("Converted byte array as: ");
for (int i = 0; i < buf2.length; i++)
System.out.print(buf2[i] + " ");
System.out.println();
System.out.println("Trying to decode a bogus string...");
buf2 = Base64.decode("ADDFDSFasdfasdf%$###");
System.out.println("Done.");
}
}
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