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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  package org.apache.shiro.crypto;
20  
21  /**
22   * {@code CipherService} using the {@code AES} cipher algorithm for all encryption, decryption, and key operations.
23   * <p/>
24   * The AES algorithm can support key sizes of {@code 128}, {@code 192} and {@code 256} bits<b>*</b>.  This implementation
25   * defaults to 128 bits.
26   * <p/>
27   * Note that this class retains the parent class's default {@link OperationMode#CBC CBC} mode of operation
28   * instead of the typical JDK default of {@link OperationMode#ECB ECB}.  {@code ECB} should not be used in
29   * security-sensitive environments because {@code ECB} does not allow for initialization vectors, which are
30   * considered necessary for strong encryption.  See the {@link DefaultBlockCipherService parent class}'s JavaDoc and the
31   * {@link JcaCipherService JcaCipherService} JavaDoc for more on why the JDK default should not be used and is not
32   * used in this implementation.
33   * <p/>
34   * <b>*</b> Generating and using AES key sizes greater than 128 require installation of the
35   * <a href="http://java.sun.com/javase/downloads/index.jsp">Java Cryptography Extension (JCE) Unlimited Strength
36   * Jurisdiction Policy files</a>.
37   *
38   * @since 1.0
39   */
40  public class AesCipherService extends DefaultBlockCipherService {
41  
42      private static final String ALGORITHM_NAME = "AES";
43  
44      /**
45       * Creates a new {@link CipherService} instance using the {@code AES} cipher algorithm with the following
46       * important cipher default attributes:
47       * <table>
48       * <tr>
49       * <th>Attribute</th>
50       * <th>Value</th>
51       * </tr>
52       * <tr>
53       * <td>{@link #setKeySize keySize}</td>
54       * <td>{@code 128} bits</td>
55       * </tr>
56       * <tr>
57       * <td>{@link #setBlockSize blockSize}</td>
58       * <td>{@code 128} bits (required for {@code AES}</td>
59       * </tr>
60       * <tr>
61       * <td>{@link #setMode mode}</td>
62       * <td>{@link OperationMode#CBC CBC}<b>*</b></td>
63       * </tr>
64       * <tr>
65       * <td>{@link #setPaddingScheme paddingScheme}</td>
66       * <td>{@link PaddingScheme#PKCS5 PKCS5}</td>
67       * </tr>
68       * <tr>
69       * <td>{@link #setInitializationVectorSize(int) initializationVectorSize}</td>
70       * <td>{@code 128} bits</td>
71       * </tr>
72       * <tr>
73       * <td>{@link #setGenerateInitializationVectors(boolean) generateInitializationVectors}</td>
74       * <td>{@code true}<b>**</b></td>
75       * </tr>
76       * </table>
77       * <p/>
78       * <b>*</b> The {@link OperationMode#CBC CBC} operation mode is used instead of the JDK default {@code ECB} to
79       * ensure strong encryption.  {@code ECB} should not be used in security-sensitive environments - see the
80       * {@link DefaultBlockCipherService DefaultBlockCipherService} class JavaDoc's &quot;Operation Mode&quot; section
81       * for more.
82       * <p/>
83       * <b>**</b>In conjunction with the default {@code CBC} operation mode, initialization vectors are generated by
84       * default to ensure strong encryption.  See the {@link JcaCipherService JcaCipherService} class JavaDoc for more.
85       */
86      public AesCipherService() {
87          super(ALGORITHM_NAME);
88      }
89  
90  }