1/*
2 * Copyright (c) 2015, 2017, 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 sun.security.util;
27
28import java.util.HashSet;
29import java.util.Set;
30import java.util.Arrays;
31import java.util.Collection;
32import java.util.regex.Pattern;
33
34/**
35 * The class decomposes standard algorithms into sub-elements.
36 */
37public class AlgorithmDecomposer {
38
39    // '(?<!padd)in': match 'in' but not preceded with 'padd'.
40    private static final Pattern PATTERN =
41            Pattern.compile("with|and|(?<!padd)in", Pattern.CASE_INSENSITIVE);
42
43    private static Set<String> decomposeImpl(String algorithm) {
44        Set<String> elements = new HashSet<>();
45
46        // algorithm/mode/padding
47        String[] transTokens = algorithm.split("/");
48
49        for (String transToken : transTokens) {
50            if (transToken == null || transToken.isEmpty()) {
51                continue;
52            }
53
54            // PBEWith<digest>And<encryption>
55            // PBEWith<prf>And<encryption>
56            // OAEPWith<digest>And<mgf>Padding
57            // <digest>with<encryption>
58            // <digest>with<encryption>and<mgf>
59            // <digest>with<encryption>in<format>
60            String[] tokens = PATTERN.split(transToken);
61
62            for (String token : tokens) {
63                if (token == null || token.isEmpty()) {
64                    continue;
65                }
66
67                elements.add(token);
68            }
69        }
70        return elements;
71    }
72
73    /**
74     * Decompose the standard algorithm name into sub-elements.
75     * <p>
76     * For example, we need to decompose "SHA1WithRSA" into "SHA1" and "RSA"
77     * so that we can check the "SHA1" and "RSA" algorithm constraints
78     * separately.
79     * <p>
80     * Please override the method if need to support more name pattern.
81     */
82    public Set<String> decompose(String algorithm) {
83        if (algorithm == null || algorithm.length() == 0) {
84            return new HashSet<>();
85        }
86
87        Set<String> elements = decomposeImpl(algorithm);
88
89        // In Java standard algorithm name specification, for different
90        // purpose, the SHA-1 and SHA-2 algorithm names are different. For
91        // example, for MessageDigest, the standard name is "SHA-256", while
92        // for Signature, the digest algorithm component is "SHA256" for
93        // signature algorithm "SHA256withRSA". So we need to check both
94        // "SHA-256" and "SHA256" to make the right constraint checking.
95
96        // handle special name: SHA-1 and SHA1
97        if (elements.contains("SHA1") && !elements.contains("SHA-1")) {
98            elements.add("SHA-1");
99        }
100        if (elements.contains("SHA-1") && !elements.contains("SHA1")) {
101            elements.add("SHA1");
102        }
103
104        // handle special name: SHA-224 and SHA224
105        if (elements.contains("SHA224") && !elements.contains("SHA-224")) {
106            elements.add("SHA-224");
107        }
108        if (elements.contains("SHA-224") && !elements.contains("SHA224")) {
109            elements.add("SHA224");
110        }
111
112        // handle special name: SHA-256 and SHA256
113        if (elements.contains("SHA256") && !elements.contains("SHA-256")) {
114            elements.add("SHA-256");
115        }
116        if (elements.contains("SHA-256") && !elements.contains("SHA256")) {
117            elements.add("SHA256");
118        }
119
120        // handle special name: SHA-384 and SHA384
121        if (elements.contains("SHA384") && !elements.contains("SHA-384")) {
122            elements.add("SHA-384");
123        }
124        if (elements.contains("SHA-384") && !elements.contains("SHA384")) {
125            elements.add("SHA384");
126        }
127
128        // handle special name: SHA-512 and SHA512
129        if (elements.contains("SHA512") && !elements.contains("SHA-512")) {
130            elements.add("SHA-512");
131        }
132        if (elements.contains("SHA-512") && !elements.contains("SHA512")) {
133            elements.add("SHA512");
134        }
135
136        return elements;
137    }
138
139    /**
140     * Get aliases of the specified algorithm.
141     *
142     * May support more algorithms in the future.
143     */
144    public static Collection<String> getAliases(String algorithm) {
145        String[] aliases;
146        if (algorithm.equalsIgnoreCase("DH") ||
147                algorithm.equalsIgnoreCase("DiffieHellman")) {
148            aliases = new String[] {"DH", "DiffieHellman"};
149        } else {
150            aliases = new String[] {algorithm};
151        }
152
153        return Arrays.asList(aliases);
154    }
155
156    private static void hasLoop(Set<String> elements, String find, String replace) {
157        if (elements.contains(find)) {
158            if (!elements.contains(replace)) {
159                elements.add(replace);
160            }
161            elements.remove(find);
162        }
163    }
164
165    /*
166     * This decomposes a standard name into sub-elements with a consistent
167     * message digest algorithm name to avoid overly complicated checking.
168     */
169    public static Set<String> decomposeOneHash(String algorithm) {
170        if (algorithm == null || algorithm.length() == 0) {
171            return new HashSet<>();
172        }
173
174        Set<String> elements = decomposeImpl(algorithm);
175
176        hasLoop(elements, "SHA-1", "SHA1");
177        hasLoop(elements, "SHA-224", "SHA224");
178        hasLoop(elements, "SHA-256", "SHA256");
179        hasLoop(elements, "SHA-384", "SHA384");
180        hasLoop(elements, "SHA-512", "SHA512");
181
182        return elements;
183    }
184
185    /*
186     * The provided message digest algorithm name will return a consistent
187     * naming scheme.
188     */
189    public static String hashName(String algorithm) {
190        return algorithm.replace("-", "");
191    }
192}
193