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/*
 * =============================================================================
 * 
 *   Copyright (c) 2007-2010, The JASYPT team (http://www.jasypt.org)
 * 
 *   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.jasypt.salt;

import java.io.UnsupportedEncodingException;

import org.jasypt.commons.CommonUtils;
import org.jasypt.exceptions.EncryptionInitializationException;

/**
 * 
 * This implementation of {@link SaltGenerator} always returns a fixed salt
 * set by the user as a String, which is returned as salt bytes using the 
 * specified charset for conversion (UTF-8 by default).
 * 
 * 
 * If the requested salt has a size in bytes smaller than the specified salt, 
 * the first n bytes are returned. If it is larger, an exception is thrown.
 * 
 * 
 * This class is thread-safe.
 * 
 * 
 * @since 1.2
 * 
 * @author Daniel Fernández
 * 
 * @deprecated Deprecated in 1.9.2 in favour of {@link StringFixedSaltGenerator}, which
 *             implements the new {@link FixedSaltGenerator} interface and therefore is able to benefit
 *             from the performance improvements associated with it. This class will be removed
 *             in 1.10.0 (or 2.0.0).
 * 
 */
public class FixedStringSaltGenerator implements SaltGenerator {

    private static final String DEFAULT_CHARSET = "UTF-8";
    
    private String salt = null;
    private String charset = DEFAULT_CHARSET;
    
    private byte[] saltBytes = null;
    
    /**
     * Creates a new instance of FixedStringSaltGenerator
     *
     */
    public FixedStringSaltGenerator() {
        super();
    }

    
    /**
     * Sets the salt to be returned.
     * 
     * @param salt the specified salt.
     */
    public synchronized void setSalt(final String salt) {
        CommonUtils.validateNotNull(salt, "Salt cannot be set null");
        this.salt = salt;
    }

    
    /**
     * Sets the charset to be applied to the salt for conversion into bytes.
     * 
     * @param charset the specified charset
     */
    public synchronized void setCharset(final String charset) {
        CommonUtils.validateNotNull(charset, "Charset cannot be set null");
        this.charset = charset;
    }

    
    /**
     * Return salt with the specified byte length.
     * 
     * @param lengthBytes length in bytes.
     * @return the generated salt. 
     */
    public byte[] generateSalt(final int lengthBytes) {
        if (this.salt == null) {
            throw new EncryptionInitializationException(
                    "Salt has not been set");
        }
        if (this.saltBytes == null) {
            try {
                this.saltBytes = this.salt.getBytes(this.charset);
            } catch (UnsupportedEncodingException e) {
                throw new EncryptionInitializationException(
                    "Invalid charset specified: " + this.charset);
            }
        }
        if (this.saltBytes.length < lengthBytes) {
            throw new EncryptionInitializationException(
                    "Requested salt larger than set");
        }
        final byte[] generatedSalt = new byte[lengthBytes];
        System.arraycopy(this.saltBytes, 0, generatedSalt, 0, lengthBytes);
        return generatedSalt;
    }


    /**
     * As this salt generator provides a fixed salt, its inclusion 
     * unencrypted in encryption results
     * is not necessary, and in fact not desirable (so that it remains hidden).
     * 
     * @return false
     */
    public boolean includePlainSaltInEncryptionResults() {
        return false;
    }

    
}