hunt.shiro.crypto.hash.HashService source code

1 /*
2  * Licensed to the Apache Software Foundation (ASF) under one
3  * or more contributor license agreements.  See the NOTICE file
4  * distributed with this work for additional information
5  * regarding copyright ownership.  The ASF licenses this file
6  * to you under the Apache License, Version 2.0 (the
7  * "License"); you may not use this file except in compliance
8  * with the License.  You may obtain a copy of the License at
9  *
10  * http://www.apache.org/licenses/LICENSE-2.0
11  *
12  * Unless required by applicable law or agreed to in writing,
13  * software distributed under the License is distributed on an
14  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15  * KIND, either express or implied.  See the License for the
16  * specific language governing permissions and limitations
17  * under the License.
18  */
19 module hunt.shiro.crypto.hash.HashService;
20 
21 import hunt.shiro.crypto.hash.Hash;
22 import hunt.shiro.crypto.hash.HashRequest;
23 
24 /**
25  * A {@code HashService} hashes input sources utilizing a particular hashing strategy.
26  * <p/>
27  * A {@code HashService} sits at a higher architectural level than Shiro's simple {@link Hash} classes:  it allows
28  * for salting and iteration-related strategies to be configured and internalized in a
29  * single component that can be re-used in multiple places in the application.
30  * <p/>
31  * For example, for the most secure hashes, it is highly recommended to use a randomly generated salt, potentially
32  * paired with an configuration-specific private salt, in addition to using multiple hash iterations.
33  * <p/>
34  * While one can do this easily enough using Shiro's {@link Hash} implementations directly, this direct approach could
35  * quickly lead to copy-and-paste behavior.  For example, consider this logic which might need to repeated in an
36  * application:
37  * <pre>
38  * int numHashIterations = ...
39  * ByteSource privateSalt = ...
40  * ByteSource randomSalt = {@link hunt.shiro.crypto.RandomNumberGenerator randomNumberGenerator}.nextBytes();
41  * ByteSource combined = combine(privateSalt, randomSalt);
42  * Hash hash = Sha512Hash(source, combined, numHashIterations);
43  * save(hash);
44  * </pre>
45  * In this example, often only the input source will change during runtime, while the hashing strategy (how salts
46  * are generated or acquired, how many hash iterations will be performed, etc) usually remain consistent.  A HashService
47  * internalizes this logic so the above becomes simply this:
48  * <pre>
49  * HashRequest request = new HashRequest.Builder().source(source).build();
50  * Hash result = hashService.hash(request);
51  * save(result);
52  * </pre>
53  *
54  */
55 interface HashService {
56 
57     /**
58      * Computes a hash based on the given request.
59      *
60      * <h3>Salt Notice</h3>
61      *
62      * If a salt accompanies the return value
63      * (i.e. <code>returnedHash.{@link hunt.shiro.crypto.hash.Hash#getSalt() getSalt()} !is null</code>), this
64      * same exact salt <b><em>MUST</em></b> be presented back to the {@code HashService} if hash
65      * comparison/verification will be performed at a later time (for example, for password hash or file checksum
66      * comparison).
67      * <p/>
68      * For additional security, the {@code HashService}'s internal implementation may use more complex salting
69      * strategies than what would be achieved by computing a {@code Hash} manually.
70      * <p/>
71      * In summary, if a {@link HashService} returns a salt in a returned Hash, it is expected that the same salt
72      * will be provided to the same {@code HashService} instance.
73      *
74      * @param request the request to process
75      * @return the hashed data
76      * @see Hash#getSalt()
77      */
78     Hash computeHash(HashRequest request);
79 }