1 /*
2  * Copyright (c) 2018, 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 import java.util.Objects;
30 
31 /**
32  * This class specifies the parameters used with the
33  * <a href="https://tools.ietf.org/html/rfc7539"><i>ChaCha20</i></a>
34  * algorithm.
35  *
36  * <p> The parameters consist of a 12-byte nonce and an initial
37  * counter value expressed as a 32-bit integer.
38  *
39  * <p> This class can be used to initialize a {@code Cipher} object that
40  * implements the <i>ChaCha20</i> algorithm.
41  *
42  * @since 11
43  */
44 public final class ChaCha20ParameterSpec implements AlgorithmParameterSpec {
45 
46     // The nonce length is defined by the spec as 96 bits (12 bytes) in length.
47     private static final int NONCE_LENGTH = 12;
48 
49     private final byte[] nonce;
50     private final int counter;
51 
52     /**
53      * Constructs a parameter set for ChaCha20 from the given nonce
54      * and counter.
55      *
56      * @param nonce a 12-byte nonce value
57      * @param counter the initial counter value
58      *
59      * @throws NullPointerException if {@code nonce} is {@code null}
60      * @throws IllegalArgumentException if {@code nonce} is not 12 bytes
61      *      in length
62      */
ChaCha20ParameterSpec(byte[] nonce, int counter)63     public ChaCha20ParameterSpec(byte[] nonce, int counter) {
64         this.counter = counter;
65 
66         Objects.requireNonNull(nonce, "Nonce must be non-null");
67         this.nonce = nonce.clone();
68         if (this.nonce.length != NONCE_LENGTH) {
69             throw new IllegalArgumentException(
70                     "Nonce must be 12-bytes in length");
71         }
72     }
73 
74     /**
75      * Returns the nonce value.
76      *
77      * @return the nonce value.  This method returns a new array each time
78      * this method is called.
79      */
getNonce()80     public byte[] getNonce() {
81         return nonce.clone();
82     }
83 
84     /**
85      * Returns the configured counter value.
86      *
87      * @return the counter value
88      */
getCounter()89     public int getCounter() {
90         return counter;
91     }
92 }
93