no.sesat.search.security.MD5Generator.java Source code

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Here is the source code for no.sesat.search.security.MD5Generator.java

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/* Copyright (2012) Schibsted ASA
 * This file is part of Possom.
 *
 *   Possom is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU Lesser General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   Possom is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public License
 *   along with Possom.  If not, see <http://www.gnu.org/licenses/>.
 */
package no.sesat.search.security;

import org.apache.commons.codec.binary.Hex;

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

/**
 *
 * @version <tt>$Revision$</tt>
 */
public final class MD5Generator {

    private static final byte[] EMPTY_STRING = new byte[0];

    private final String secret;

    public MD5Generator(final String secret) {

        this.secret = secret;
    }

    public String generateMD5(final String s) {

        final MessageDigest digest = getDigest("MD5");

        digest.update(null != s ? s.getBytes() : EMPTY_STRING);
        digest.update(secret.getBytes());

        return String.valueOf(Hex.encodeHex(digest.digest()));
    }

    public boolean validate(final String s, final String hash) {

        return generateMD5(s).equals(hash);

    }

    /**
     * Returns a MessageDigest for the given <code>algorithm</code>.
     *
     * @param algorithm The MessageDigest algorithm name.
     * @return An digest instance.
     * @throws RuntimeException when a {@link java.security.NoSuchAlgorithmException} is caught,
     */
    static MessageDigest getDigest(String algorithm) {

        try {
            return MessageDigest.getInstance(algorithm);
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException(e.getMessage());
        }
    }
}