org.nebulaframework.util.hashing.SHA1Generator.java Source code

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Here is the source code for org.nebulaframework.util.hashing.SHA1Generator.java

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/*
 * Copyright (C) 2008 Yohan Liyanage. 
 * 
 * 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 
 * 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.nebulaframework.util.hashing;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.util.Assert;

/**
 * A utility class which generates SHA1 hash for a given
 * {@code byte[]} or a {@code String}.
 * 
 * @author Yohan Liyanage
 * @version 1.0
 */
public class SHA1Generator {

    private static Log log = LogFactory.getLog(SHA1Generator.class);

    /**
     * Generates SHA1 Hash for the given {@code byte[]} and returns
     * the hash code as a {@code byte[]}.
     * 
     * @param source source value
     * @return SHA-1 hash for value
     * 
     * @see #generate(String)
     * @see #generateAsString(byte[])
     * 
     * @throws IllegalArgumentException if {@code source} is {@code null}
     */
    public static byte[] generate(byte[] source) throws IllegalArgumentException {

        // Check for nulls
        Assert.notNull(source);

        try {
            MessageDigest digest = MessageDigest.getInstance("SHA");
            digest.update(source);
            return digest.digest();
        } catch (NoSuchAlgorithmException e) {
            log.fatal("Cannot load hashing algorithm", e);
            throw new RuntimeException(e);
        }
    }

    /**
     * Generates SHA1 Hash for the given {@code byte[]} and returns
     * the hash code as a {@code String}.
     * 
     * @param source source value
     * @return SHA-1 hash for value
     * 
     * @see #generate(byte[])
     * @see #generate(String)
     * 
     * @throws IllegalArgumentException if {@code source} is {@code null}
     */
    public static String generateAsString(byte[] source) throws IllegalArgumentException {
        return bytesToString(generate(source));
    }

    /**
     * Overloaded version generates SHA1 Hash for the given {@code String} 
     * and returns the hash code as a {@code String}.
     * 
     * @param source source value
     * @return SHA-1 hash for value
     * 
     * @see #generate(byte[])
     * @see #generateAsString(byte[])
     * 
     * @throws IllegalArgumentException if {@code source} is {@code null}
     */
    public static String generate(String source) throws IllegalArgumentException {
        return bytesToString(generate(source.getBytes()));
    }

    /**
     * Support method which converts a given {@code byte[]}
     * to a HEX String.
     * 
     * @param bytes {@code byte[]} to convert
     * @return {@code String} representation (hex)
     * 
     * @throws IllegalArgumentException if {@code bytes} is {@code null}
     */
    private static String bytesToString(byte[] bytes) throws IllegalArgumentException {

        // Check for nulls
        Assert.notNull(bytes);

        StringBuilder sb = new StringBuilder();

        // Convert each byte to HEX String format
        for (int i = 0; i < bytes.length; i++) {
            sb.append(String.format("%02X%s", bytes[i], (i < bytes.length - 1) ? "-" : ""));
        }
        return sb.toString();
    }
}