/**
 * Copyright (c) 2003-2005, www.pdfbox.org
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. Neither the name of pdfbox; nor the names of its
 *    contributors may be used to endorse or promote products derived from this
 *    software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * http://www.pdfbox.org
 *
 */

package org.pdfbox.pdmodel.encryption;

/**
 * This class represents the protection policy to apply to a document.
 * 
 * Objects implementing this abstract class can be passed to the protect method of PDDocument
 * to protect a document.
 * 
 * @see org.pdfbox.pdmodel.PDDocument#protect(ProtectionPolicy)
 *  
 * @author Benoit Guillon (benoit.guillon@snv.jussieu.fr)
 * @version $Revision: 1.2 $
 */
public abstract class ProtectionPolicy 
{

    private static final int DEFAULT_KEY_LENGTH = 40;
    
    private int encryptionKeyLength = DEFAULT_KEY_LENGTH;
    
    /**
     * set the length in (bits) of the secret key that will be 
     * used to encrypt document data.
     * The default value is 40 bits, which provides a low security level
     * but is compatible with old versions of Acrobat Reader.
     * 
     * @param l the length in bits (must be 40 or 128)
     */    
    public void setEncryptionKeyLength(int l)
    {
        if(l!=40 && l!=128)
        {
            throw new RuntimeException("Invalid key length");
        }
        encryptionKeyLength = l;
    }
    
    /**
     * Get the length of the secrete key that will be used to encrypt
     * document data.
     * 
     * @return The length (in bits) of the encryption key.
     */
    public int getEncryptionKeyLength()
    {
        return encryptionKeyLength;
    }
}