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1   /* Copyright 2004 Acegi Technology Pty Limited
2    *
3    * Licensed under the Apache License, Version 2.0 (the "License");
4    * you may not use this file except in compliance with the License.
5    * You may obtain a copy of the License at
6    *
7    *     http://www.apache.org/licenses/LICENSE-2.0
8    *
9    * Unless required by applicable law or agreed to in writing, software
10   * distributed under the License is distributed on an "AS IS" BASIS,
11   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12   * See the License for the specific language governing permissions and
13   * limitations under the License.
14   */
15  
16  package org.acegisecurity.providers.encoding;
17  
18  import org.springframework.dao.DataAccessException;
19  
20  
21  /***
22   * <p>
23   * Interface for performing authentication operations on a password.
24   * </p>
25   *
26   * @author colin sampaleanu
27   * @version $Id: PasswordEncoder.java,v 1.5 2005/11/17 00:55:49 benalex Exp $
28   */
29  public interface PasswordEncoder {
30      //~ Methods ================================================================
31  
32      /***
33       * <p>
34       * Validates a specified "raw" password against an encoded password.
35       * </p>
36       * 
37       * <P>
38       * The encoded password should have previously been generated by {@link
39       * #encodePassword(String, Object)}. This method will encode the
40       * <code>rawPass</code> (using the optional <code>salt</code>),  and then
41       * compared it with the presented <code>encPass</code>.
42       * </p>
43       * 
44       * <p>
45       * For a discussion of salts, please refer to {@link
46       * #encodePassword(String, Object)}.
47       * </p>
48       *
49       * @param encPass a pre-encoded password
50       * @param rawPass a raw password to encode and compare against the
51       *        pre-encoded password
52       * @param salt optionally used by the implementation to "salt" the raw
53       *        password before encoding. A <code>null</code> value is legal.
54       *
55       * @return DOCUMENT ME!
56       */
57      public boolean isPasswordValid(String encPass, String rawPass, Object salt)
58          throws DataAccessException;
59  
60      /***
61       * <p>
62       * Encodes the specified raw password with an implementation specific
63       * algorithm.
64       * </p>
65       * 
66       * <P>
67       * This will generally be a one-way message digest such as MD5 or SHA, but
68       * may also be a plaintext variant which does no encoding at all, but
69       * rather returns the same password it was fed. The latter is useful to
70       * plug in when the original password must be stored as-is.
71       * </p>
72       * 
73       * <p>
74       * The specified salt will potentially be used by the implementation to
75       * "salt" the initial value before encoding. A salt is usually a
76       * user-specific value which is added to the password before the digest is
77       * computed. This means that computation of digests for common dictionary
78       * words will be different than those in the backend store, because the
79       * dictionary word digests will not reflect the addition of the salt. If a
80       * per-user salt is used (rather than a system-wide salt), it also means
81       * users with the same password will have different digest encoded
82       * passwords in the backend store.
83       * </p>
84       * 
85       * <P>
86       * If a salt value is provided, the same salt value must be use when
87       * calling the  {@link #isPasswordValid(String, String, Object)} method.
88       * Note that a specific implementation may choose to ignore the salt value
89       * (via <code>null</code>), or provide its own.
90       * </p>
91       *
92       * @param rawPass the password to encode
93       * @param salt optionally used by the implementation to "salt" the raw
94       *        password before encoding. A <code>null</code> value is legal.
95       *
96       * @return DOCUMENT ME!
97       */
98      public String encodePassword(String rawPass, Object salt)
99          throws DataAccessException;
100 }