View Javadoc
1   /*
2    * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
3    * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4    *
5    * This code is free software; you can redistribute it and/or modify it
6    * under the terms of the GNU General Public License version 2 only, as
7    * published by the Free Software Foundation.  Oracle designates this
8    * particular file as subject to the "Classpath" exception as provided
9    * by Oracle in the LICENSE file that accompanied this code.
10   *
11   * This code is distributed in the hope that it will be useful, but WITHOUT
12   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14   * version 2 for more details (a copy is included in the LICENSE file that
15   * accompanied this code).
16   *
17   * You should have received a copy of the GNU General Public License version
18   * 2 along with this work; if not, write to the Free Software Foundation,
19   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20   *
21   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22   * or visit www.oracle.com if you need additional information or have any
23   * questions.
24   */
25  
26  package javax.crypto.spec;
27  
28  import java.security.spec.AlgorithmParameterSpec;
29  
30  /**
31   * This class specifies an <i>initialization vector</i> (IV).
32   * Examples which use IVs are ciphers in feedback mode,
33   * e.g., DES in CBC mode and RSA ciphers with OAEP encoding
34   * operation.
35   *
36   * @author Jan Luehe
37   *
38   * @since 1.4
39   */
40  public class IvParameterSpec implements AlgorithmParameterSpec {
41  
42      private byte[] iv;
43  
44      /**
45       * Creates an IvParameterSpec object using the bytes in <code>iv</code>
46       * as the IV.
47       *
48       * @param iv the buffer with the IV. The contents of the
49       * buffer are copied to protect against subsequent modification.
50       * @throws NullPointerException if <code>iv</code> is <code>null</code>
51       */
52      public IvParameterSpec(byte[] iv) {
53          this(iv, 0, iv.length);
54      }
55  
56      /**
57       * Creates an IvParameterSpec object using the first <code>len</code>
58       * bytes in <code>iv</code>, beginning at <code>offset</code>
59       * inclusive, as the IV.
60       *
61       * <p> The bytes that constitute the IV are those between
62       * <code>iv[offset]</code> and <code>iv[offset+len-1]</code> inclusive.
63       *
64       * @param iv the buffer with the IV. The first <code>len</code>
65       * bytes of the buffer beginning at <code>offset</code> inclusive
66       * are copied to protect against subsequent modification.
67       * @param offset the offset in <code>iv</code> where the IV
68       * starts.
69       * @param len the number of IV bytes.
70       * @throws IllegalArgumentException if <code>iv</code> is <code>null</code>
71       * or {@code (iv.length - offset < len)}
72       * @throws ArrayIndexOutOfBoundsException is thrown if <code>offset</code>
73       * or <code>len</code> index bytes outside the <code>iv</code>.
74       */
75      public IvParameterSpec(byte[] iv, int offset, int len) {
76          if (iv == null) {
77              throw new IllegalArgumentException("IV missing");
78          }
79          if (iv.length - offset < len) {
80              throw new IllegalArgumentException
81                  ("IV buffer too short for given offset/length combination");
82          }
83          if (len < 0) {
84              throw new ArrayIndexOutOfBoundsException("len is negative");
85          }
86          this.iv = new byte[len];
87          System.arraycopy(iv, offset, this.iv, 0, len);
88      }
89  
90      /**
91       * Returns the initialization vector (IV).
92       *
93       * @return the initialization vector (IV). Returns a new array
94       * each time this method is called.
95       */
96      public byte[] getIV() {
97          return this.iv.clone();
98      }
99  }