/* Copyright 2004, 2005, 2006 Acegi Technology Pty Limited

  *

  * 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.acegisecurity.providers.encoding;

 import org.springframework.dao.DataAccessException;

 /**

  * <p>

  * Interface for performing authentication operations on a password.

  * </p>

  *

  * @author colin sampaleanu

  * @version $Id: PasswordEncoder.java 1784 2007-02-24 21:00:24Z luke_t $

  */

 public interface PasswordEncoder {

     //~ Methods ========================================================================================================

     /**

      * <p>Encodes the specified raw password with an implementation specific algorithm.</p>

      *  <P>This will generally be a one-way message digest such as MD5 or SHA, but may also be a plaintext

      * variant which does no encoding at all, but rather returns the same password it was fed. The latter is useful to

      * plug in when the original password must be stored as-is.</p>

      *  <p>The specified salt will potentially be used by the implementation to "salt" the initial value before

      * encoding. A salt is usually a user-specific value which is added to the password before the digest is computed.

      * This means that computation of digests for common dictionary words will be different than those in the backend

      * store, because the dictionary word digests will not reflect the addition of the salt. If a per-user salt is

      * used (rather than a system-wide salt), it also means users with the same password will have different digest

      * encoded passwords in the backend store.</p>

      *  <P>If a salt value is provided, the same salt value must be use when calling the  {@link

      * #isPasswordValid(String, String, Object)} method. Note that a specific implementation may choose to ignore the

      * salt value (via <code>null</code>), or provide its own.</p>

      *

      * @param rawPass the password to encode

      * @param salt optionally used by the implementation to "salt" the raw password before encoding. A

      *        <code>null</code> value is legal.

      *

      * @return encoded password

      *

      * @throws DataAccessException DOCUMENT ME!

      */

     String encodePassword(String rawPass, Object salt)

         throws DataAccessException;

     /**

      * <p>Validates a specified "raw" password against an encoded password.</p>

      *  <P>The encoded password should have previously been generated by {@link #encodePassword(String,

      * Object)}. This method will encode the <code>rawPass</code> (using the optional <code>salt</code>),  and then

      * compared it with the presented <code>encPass</code>.</p>

      *  <p>For a discussion of salts, please refer to {@link #encodePassword(String, Object)}.</p>

      *

      * @param encPass a pre-encoded password

      * @param rawPass a raw password to encode and compare against the pre-encoded password

      * @param salt optionally used by the implementation to "salt" the raw password before encoding. A

      *        <code>null</code> value is legal.

      *

      * @return true if the password is valid , false otherwise

      *

      * @throws DataAccessException DOCUMENT ME!

      */

     boolean isPasswordValid(String encPass, String rawPass, Object salt)

         throws DataAccessException;

 }