org.springframework.security.crypto.codec.Hex.java Source code

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Here is the source code for org.springframework.security.crypto.codec.Hex.java

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/*
 * 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.
 * <p>
 * For internal use only.
 *
 * @author Luke Taylor
 * @since 3.0
 */
public final class Hex {

    private static final char[] HEX = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e',
            'f' };

    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;
    }

}