/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.apache.shiro.codec;
/**
* <a href="http://en.wikipedia.org/wiki/Hexadecimal">Hexadecimal</a> encoder and decoder.
* <p/>
* This class was borrowed from Apache Commons Codec SVN repository (rev. {@code 560660}) with modifications
* to enable Hex conversion without a full dependency on Commons Codec. We didn't want to reinvent the wheel of
* great work they've done, but also didn't want to force every Shiro user to depend on the commons-codec.jar
* <p/>
* As per the Apache 2.0 license, the original copyright notice and all author and copyright information have
* remained in tact.
*
* @see <a href="http://en.wikipedia.org/wiki/Hexadecimal">Wikipedia: Hexadecimal</a>
* @since 0.9
*/
public class Hex {
/**
* Used to build output as Hex
*/
private static final char[] DIGITS = {
'0', '1', '2', '3', '4', '5', '6', '7',
'8', '9', 'a', 'b', 'c', 'd', 'e', 'f'
};
/**
* Encodes the specified byte array to a character array and then returns that character array
* as a String.
*
* @param bytes the byte array to Hex-encode.
* @return A String representation of the resultant hex-encoded char array.
*/
public static String encodeToString(byte[] bytes) {
char[] encodedChars = encode(bytes);
return new String(encodedChars);
}
/**
* Converts an array of bytes into an array of characters representing the hexadecimal values of each byte in order.
* The returned array will be double the length of the passed array, as it takes two characters to represent any
* given byte.
*
* @param data byte[] to convert to Hex characters
* @return A char[] containing hexadecimal characters
*/
public static char[] encode(byte[] data) {
int l = data.length;
char[] out = new char[l << 1];
// two characters form the hex value.
for (int i = 0, j = 0; i < l; i++) {
out[j++] = DIGITS[(0xF0 & data[i]) >>> 4];
out[j++] = DIGITS[0x0F & data[i]];
}
return out;
}
/**
* Converts an array of character bytes representing hexadecimal values into an
* array of bytes of those same values. The returned array will be half the
* length of the passed array, as it takes two characters to represent any
* given byte. An exception is thrown if the passed char array has an odd
* number of elements.
*
* @param array An array of character bytes containing hexadecimal digits
* @return A byte array containing binary data decoded from
* the supplied byte array (representing characters).
* @throws IllegalArgumentException Thrown if an odd number of characters is supplied
* to this function
* @see #decode(char[])
*/
public static byte[] decode(byte[] array) throws IllegalArgumentException {
String s = CodecSupport.toString(array);
return decode(s);
}
/**
* Converts the specified Hex-encoded String into a raw byte array. This is a
* convenience method that merely delegates to {@link #decode(char[])} using the
* argument's hex.toCharArray() value.
*
* @param hex a Hex-encoded String.
* @return A byte array containing binary data decoded from the supplied String's char array.
*/
public static byte[] decode(String hex) {
return decode(hex.toCharArray());
}
/**
* Converts an array of characters representing hexadecimal values into an
* array of bytes of those same values. The returned array will be half the
* length of the passed array, as it takes two characters to represent any
* given byte. An exception is thrown if the passed char array has an odd
* number of elements.
*
* @param data An array of characters containing hexadecimal digits
* @return A byte array containing binary data decoded from
* the supplied char array.
* @throws IllegalArgumentException if an odd number or illegal of characters
* is supplied
*/
public static byte[] decode(char[] data) throws IllegalArgumentException {
int len = data.length;
if ((len & 0x01) != 0) {
throw new IllegalArgumentException("Odd number of characters.");
}
byte[] out = new byte[len >> 1];
// two characters form the hex value.
for (int i = 0, j = 0; j < len; i++) {
int f = toDigit(data[j], j) << 4;
j++;
f = f | toDigit(data[j], j);
j++;
out[i] = (byte) (f & 0xFF);
}
return out;
}
/**
* Converts a hexadecimal character to an integer.
*
* @param ch A character to convert to an integer digit
* @param index The index of the character in the source
* @return An integer
* @throws IllegalArgumentException if ch is an illegal hex character
*/
protected static int toDigit(char ch, int index) throws IllegalArgumentException {
int digit = Character.digit(ch, 16);
if (digit == -1) {
throw new IllegalArgumentException("Illegal hexadecimal character " + ch + " at index " + index);
}
return digit;
}
}