/*
 * =============================================================================
 * 
 *   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.encryption.pbe.config;

import java.security.Provider;

import org.jasypt.salt.SaltGenerator;


/**
 * <p>
 * Common interface for config classes applicable to 
 * {@link org.jasypt.encryption.pbe.StandardPBEByteEncryptor}, 
 * {@link org.jasypt.encryption.pbe.StandardPBEStringEncryptor},
 * {@link org.jasypt.encryption.pbe.StandardPBEBigIntegerEncryptor} or
 * {@link org.jasypt.encryption.pbe.StandardPBEBigDecimalEncryptor} objects. 
 * </p>
 * <p>
 * This interface lets the user create new <tt>PBEConfig</tt>
 * classes which retrieve values for this parameters from different
 * (and maybe more secure) sources (remote servers, LDAP, other databases...),
 * and do this transparently for the encryptor object. 
 * </p>
 * <p>
 * The config objects passed to an encryptor <u>will only be queried once</u>
 * for each configuration parameter, and this will happen 
 * during the initialization of the encryptor object. 
 * </p>
 * <p>
 * For a default implementation, see {@link SimplePBEConfig}.
 * </p>
 * 
 * @since 1.0
 * 
 * @author Daniel Fern&aacute;ndez
 * 
 */
public interface PBEConfig {

    
    /**
     * <p>
     * Returns the algorithm to be used for encryption, like 
     * <tt>PBEWithMD5AndDES</tt>.
     * </p>
     * 
     * <p>
     * This algorithm has to be supported by the specified JCE provider 
     * (or the default one if no provider has been specified) and, if the 
     * provider supports it, you can also specify <i>mode</i> and 
     * <i>padding</i> for it, like <tt>ALGORITHM/MODE/PADDING</tt>.
     * </p>
     * 
     * @return the name of the algorithm to be used.
     */
    public String getAlgorithm();

    
    /**
     * <p>
     * Returns the password to be used.
     * </p>
     * <p>
     * <b>There is no default value for password</b>, so not setting
     * this parameter either from a 
     * {@link org.jasypt.encryption.pbe.config.PBEConfig} object or from
     * a call to <tt>setPassword</tt> will result in an
     * EncryptionInitializationException being thrown during initialization.
     * </p>
     * 
     * @return the password to be used.
     */
    public String getPassword();

    
    /**
     * <p>
     * Returns the number of hashing iterations applied to obtain the
     * encryption key.
     * </p>
     * <p>
     * This mechanism is explained in 
     * <a href="http://www.rsasecurity.com/rsalabs/node.asp?id=2127" 
     * target="_blank">PKCS &#035;5: Password-Based Cryptography Standard</a>.
     * </p>
     * 
     * @return the number of iterations
     */
    public Integer getKeyObtentionIterations();

    
    /**
     * <p>
     * Returns a {@link SaltGenerator} implementation to be used by the 
     * encryptor.
     * </p>
     * <p>
     * If this method returns null, the encryptor will ignore the config object
     * when deciding the salt generator to be used.
     * </p>
     * 
     * @return the salt generator, or null if this object will not want to set
     *         a specific SaltGenerator implementation.
     */
    public SaltGenerator getSaltGenerator();
    
    
    /**
     * <p>
     * Returns the name of the <tt>java.security.Provider</tt> implementation
     * to be used by the encryptor for obtaining the encryption algorithm. This
     * provider must have been registered beforehand.
     * </p>
     * <p>
     * If this method returns null, the encryptor will ignore this parameter
     * when deciding the name of the security provider to be used.
     * </p>
     * <p>
     * If this method does not return null, and neither does {@link #getProvider()},
     * <tt>providerName</tt> will be ignored, and the provider object returned
     * by <tt>getProvider()</tt> will be used.
     * </p>
     * 
     * @since 1.3
     * 
     * @return the name of the security provider to be used.
     */
    public String getProviderName();
    
    
    /**
     * <p>
     * Returns the <tt>java.security.Provider</tt> implementation object
     * to be used by the encryptor for obtaining the encryption algorithm.
     * </p>
     * <p>
     * If this method returns null, the encryptor will ignore this parameter
     * when deciding the security provider object to be used.
     * </p>
     * <p>
     * If this method does not return null, and neither does {@link #getProviderName()},
     * <tt>providerName</tt> will be ignored, and the provider object returned
     * by <tt>getProvider()</tt> will be used.
     * </p>
     * <p>
     * The provider returned by this method <b>does not need to be
     * registered beforehand<b>, and its use will not result in its 
     * being registered.
     * </p>
     * 
     * @since 1.3
     * 
     * @return the security provider object to be asked for the digest
     *         algorithm.
     */
    public Provider getProvider();

    
    

    
    
    /**
     * <p>
     * Get the size of the pool of encryptors to be created.
     * </p>
     * <p>
     * <b>This parameter will be ignored if used with a non-pooled encryptor</b>.
     * </p>
     *
     * @since 1.7
     * 
     * @return the size of the pool to be used if this configuration is used with a
     *         pooled encryptor
     */
    public Integer getPoolSize();

    
}
