org.springframework.security.crypto.codec.Hex Maven / Gradle / Ivy
/*
* Copyright 2002-2016 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
*
* https://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.security.crypto.codec;
/**
* Hex data encoder. Converts byte arrays (such as those obtained from message digests)
* into hexadecimal string representation.
*
* For internal use only.
*
* @author Luke Taylor
* @since 3.0
*/
public final class Hex {
private static final char[] HEX = "0123456789abcdef".toCharArray();
private Hex() {
}
public static char[] encode(byte[] bytes) {
final int nBytes = bytes.length;
char[] result = new char[2 * nBytes];
int j = 0;
for (byte aByte : bytes) {
// Char for top 4 bits
result[j++] = HEX[(0xF0 & aByte) >>> 4];
// Bottom 4
result[j++] = HEX[(0x0F & aByte)];
}
return result;
}
public static byte[] decode(CharSequence s) {
int nChars = s.length();
if (nChars % 2 != 0) {
throw new IllegalArgumentException("Hex-encoded string must have an even number of characters");
}
byte[] result = new byte[nChars / 2];
for (int i = 0; i < nChars; i += 2) {
int msb = Character.digit(s.charAt(i), 16);
int lsb = Character.digit(s.charAt(i + 1), 16);
if (msb < 0 || lsb < 0) {
throw new IllegalArgumentException(
"Detected a Non-hex character at " + (i + 1) + " or " + (i + 2) + " position");
}
result[i / 2] = (byte) ((msb << 4) | lsb);
}
return result;
}
}