com.cedarsoft.crypt.Hash.java Source code

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Here is the source code for com.cedarsoft.crypt.Hash.java

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/**
 * Copyright (C) cedarsoft GmbH.
 *
 * Licensed under the GNU General Public License version 3 (the "License")
 * with Classpath Exception; you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 *         http://www.cedarsoft.org/gpl3ce
 *         (GPL 3 with Classpath Exception)
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 3 only, as
 * published by the Free Software Foundation. cedarsoft GmbH designates this
 * particular file as subject to the "Classpath" exception as provided
 * by cedarsoft GmbH in the LICENSE file that accompanied this code.
 *
 * This code 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
 * version 3 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 3 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact cedarsoft GmbH, 72810 Gomaringen, Germany,
 * or visit www.cedarsoft.com if you need additional information or
 * have any questions.
 */

package com.cedarsoft.crypt;

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

import javax.annotation.Nonnull;

import java.io.Serializable;
import java.util.Arrays;

/**
 * Represents a hash value
 *
 * @author Johannes Schneider (<a href=mailto:js@cedarsoft.com>js@cedarsoft.com</a>)
 */
public class Hash implements Serializable {
    private static final long serialVersionUID = 5728176239480983210L;

    @Nonnull
    private final Algorithm algorithm;
    @Nonnull
    private final byte[] value;

    /**
     * <p>Constructor for Hash.</p>
     *
     * @param algorithm a Algorithm object.
     * @param value     an array of byte.
     */
    public Hash(@Nonnull Algorithm algorithm, @Nonnull byte[] value) {
        this.algorithm = algorithm;
        this.value = value.clone();
    }

    /**
     * <p>Getter for the field <code>algorithm</code>.</p>
     *
     * @return a Algorithm object.
     */
    @Nonnull
    public Algorithm getAlgorithm() {
        return algorithm;
    }

    /**
     * <p>getValueAsHex</p>
     *
     * @return a String object.
     */
    @Nonnull
    public String getValueAsHex() {
        return new String(Hex.encodeHex(value));
    }

    /**
     * <p>Getter for the field <code>value</code>.</p>
     *
     * @return an array of byte.
     */
    @Nonnull
    public byte[] getValue() {
        return value.clone();
    }

    /**
     * {@inheritDoc}
     */
    @Override
    @Nonnull
    public String toString() {
        return "[" + algorithm + ": " + getValueAsHex() + "]";
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean equals(Object o) {
        if (this == o)
            return true;
        if (o == null || getClass() != o.getClass())
            return false;

        Hash hash = (Hash) o;

        if (algorithm != hash.algorithm)
            return false;
        if (!Arrays.equals(value, hash.value))
            return false;

        return true;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public int hashCode() {
        int result;
        result = algorithm.hashCode();
        result = 31 * result + (value != null ? Arrays.hashCode(value) : 0);
        return result;
    }

    /**
     * Creates a hash from the given hex value
     *
     * @param algorithm  the algorithm
     * @param valueAsHex the hex value
     * @return the hash
     */
    @Nonnull
    public static Hash fromHex(@Nonnull Algorithm algorithm, @Nonnull String valueAsHex) {
        try {
            return new Hash(algorithm, Hex.decodeHex(valueAsHex.toCharArray()));
        } catch (DecoderException e) {
            throw new IllegalArgumentException("Invalid hex string <" + valueAsHex + ">", e);
        }
    }
}