eg.nileu.cis.nilestore.cryptography.SHA256d.java Source code

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Here is the source code for eg.nileu.cis.nilestore.cryptography.SHA256d.java

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/**
 * This file is part of the Nilestore project.
 * 
 * Copyright (C) (2011) Nile University (NU)
 *
 * Nilestore is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */
package eg.nileu.cis.nilestore.cryptography;

import java.nio.charset.Charset;

import org.bouncycastle.crypto.digests.SHA256Digest;

// TODO: Auto-generated Javadoc
/**
 * The Class SHA256d.
 * 
 * @author Mahmoud Ismail <mahmoudahmedismail@gmail.com>
 */
public class SHA256d {

    /** The hasher. */
    private SHA256Digest hasher;

    /** The digest. */
    private byte[] digest;

    /** The truncate_to. */
    private int truncate_to;

    /**
     * Instantiates a new sH a256d.
     * 
     * @param truncate_to
     *            the truncate_to
     */
    public SHA256d(int truncate_to) {

        this.hasher = new SHA256Digest();
        this.truncate_to = truncate_to > hasher.getDigestSize() ? hasher.getDigestSize() : truncate_to;
        this.digest = new byte[truncate_to];
        ;
    }

    /**
     * Instantiates a new sH a256d.
     */
    public SHA256d() {
        this.hasher = new SHA256Digest();
        this.digest = new byte[hasher.getDigestSize()];
        ;
        this.truncate_to = hasher.getDigestSize();
    }

    /**
     * Update.
     * 
     * @param data
     *            the data
     */
    public void update(String data) {
        update(data.getBytes(Charset.forName("UTF-8")));
    }

    /**
     * Update.
     * 
     * @param data
     *            the data
     */
    public void update(byte[] data) {
        hasher.update(data, 0, data.length);
    }

    /**
     * Digest.
     * 
     * @return the byte[]
     */
    public byte[] digest() {
        byte[] h1 = getDigest();
        update(h1);
        byte[] h2 = getDigest();
        System.arraycopy(h2, 0, digest, 0, truncate_to);
        return digest;
    }

    /**
     * Gets the digest.
     * 
     * @return the digest
     */
    private byte[] getDigest() {
        byte[] out = new byte[hasher.getDigestSize()];
        hasher.doFinal(out, 0);
        return out;
    }
}