1/*
2 * Copyright (c) 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
26package com.sun.crypto.provider;
27
28import java.io.IOException;
29import java.security.AlgorithmParametersSpi;
30import java.security.spec.AlgorithmParameterSpec;
31import java.security.spec.InvalidParameterSpecException;
32import javax.crypto.spec.GCMParameterSpec;
33import sun.security.util.HexDumpEncoder;
34import sun.security.util.*;
35
36/**
37 * This class implements the parameter set used with
38 * GCM encryption, which is defined in RFC 5084 as follows:
39 *
40 * <pre>
41 *    GCMParameters ::= SEQUENCE {
42 *      aes-iv      OCTET STRING, -- recommended size is 12 octets
43 *      aes-tLen    AES-GCM-ICVlen DEFAULT 12 }
44 *
45 *    AES-GCM-ICVlen ::= INTEGER (12 | 13 | 14 | 15 | 16)
46 *
47 * </pre>
48 *
49 * @author Valerie Peng
50 * @since 1.8
51 */
52public final class GCMParameters extends AlgorithmParametersSpi {
53
54    // the iv
55    private byte[] iv;
56    // the tag length in bytes
57    private int tLen;
58
59    public GCMParameters() {}
60
61    protected void engineInit(AlgorithmParameterSpec paramSpec)
62        throws InvalidParameterSpecException {
63
64        if (!(paramSpec instanceof GCMParameterSpec)) {
65            throw new InvalidParameterSpecException
66                ("Inappropriate parameter specification");
67        }
68        GCMParameterSpec gps = (GCMParameterSpec) paramSpec;
69        // need to convert from bits to bytes for ASN.1 encoding
70        this.tLen = gps.getTLen()/8;
71        this.iv = gps.getIV();
72    }
73
74    protected void engineInit(byte[] encoded) throws IOException {
75        DerValue val = new DerValue(encoded);
76        // check if IV or params
77        if (val.tag == DerValue.tag_Sequence) {
78            byte[] iv = val.data.getOctetString();
79            int tLen;
80            if (val.data.available() != 0) {
81                tLen = val.data.getInteger();
82                if (tLen < 12 || tLen > 16 ) {
83                    throw new IOException
84                        ("GCM parameter parsing error: unsupported tag len: " +
85                         tLen);
86                }
87                if (val.data.available() != 0) {
88                    throw new IOException
89                        ("GCM parameter parsing error: extra data");
90                }
91            } else {
92                tLen = 12;
93            }
94            this.iv = iv.clone();
95            this.tLen = tLen;
96        } else {
97            throw new IOException("GCM parameter parsing error: no SEQ tag");
98        }
99    }
100
101    protected void engineInit(byte[] encoded, String decodingMethod)
102        throws IOException {
103        engineInit(encoded);
104    }
105
106    protected <T extends AlgorithmParameterSpec>
107            T engineGetParameterSpec(Class<T> paramSpec)
108        throws InvalidParameterSpecException {
109
110        if (GCMParameterSpec.class.isAssignableFrom(paramSpec)) {
111            return paramSpec.cast(new GCMParameterSpec(tLen * 8, iv));
112        } else {
113            throw new InvalidParameterSpecException
114                ("Inappropriate parameter specification");
115        }
116    }
117
118    protected byte[] engineGetEncoded() throws IOException {
119        DerOutputStream out = new DerOutputStream();
120        DerOutputStream bytes = new DerOutputStream();
121
122        bytes.putOctetString(iv);
123        bytes.putInteger(tLen);
124        out.write(DerValue.tag_Sequence, bytes);
125        return out.toByteArray();
126    }
127
128    protected byte[] engineGetEncoded(String encodingMethod)
129        throws IOException {
130        return engineGetEncoded();
131    }
132
133    /*
134     * Returns a formatted string describing the parameters.
135     */
136    protected String engineToString() {
137        String LINE_SEP = System.getProperty("line.separator");
138        HexDumpEncoder encoder = new HexDumpEncoder();
139        StringBuilder sb
140            = new StringBuilder(LINE_SEP + "    iv:" + LINE_SEP + "["
141                + encoder.encodeBuffer(iv) + "]");
142
143        sb.append(LINE_SEP + "tLen(bits):" + LINE_SEP + tLen*8 + LINE_SEP);
144        return sb.toString();
145    }
146}
147