1/*
2 * Copyright (C) 2013 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package libcore.javax.net.ssl;
18
19import junit.framework.Assert;
20import java.security.GeneralSecurityException;
21import java.security.KeyFactory;
22import java.security.KeyPairGenerator;
23import java.security.PrivateKey;
24import java.security.interfaces.ECPrivateKey;
25import java.security.spec.DSAParameterSpec;
26import java.security.spec.DSAPrivateKeySpec;
27import java.security.spec.RSAPrivateKeySpec;
28import java.util.HashMap;
29import java.util.Map;
30import javax.net.ssl.X509ExtendedKeyManager;
31
32/**
33 * {@link X509ExtendedKeyManager} which forwards all calls to a delegate while substituting
34 * the returned private key with its own randomly generated keys of the same type (and parameters).
35 */
36public class RandomPrivateKeyX509ExtendedKeyManager extends ForwardingX509ExtendedKeyManager {
37
38  private final Map<String, PrivateKey> cachedKeys = new HashMap<String, PrivateKey>();
39
40  public RandomPrivateKeyX509ExtendedKeyManager(X509ExtendedKeyManager delegate) {
41    super(delegate);
42  }
43
44  @Override
45  public PrivateKey getPrivateKey(String alias) {
46    PrivateKey originalPrivateKey = super.getPrivateKey(alias);
47    if (originalPrivateKey == null) {
48      return null;
49    }
50
51    PrivateKey result;
52    String keyAlgorithm = originalPrivateKey.getAlgorithm();
53    try {
54      KeyFactory keyFactory = KeyFactory.getInstance(keyAlgorithm);
55      if ("RSA".equals(keyAlgorithm)) {
56        RSAPrivateKeySpec originalKeySpec =
57            keyFactory.getKeySpec(originalPrivateKey, RSAPrivateKeySpec.class);
58        int keyLengthBits = originalKeySpec.getModulus().bitLength();
59        // Use a cache because RSA key generation is slow.
60        String cacheKey = keyAlgorithm + "-" + keyLengthBits;
61        result = cachedKeys.get(cacheKey);
62        if (result == null) {
63          KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(keyAlgorithm);
64          keyPairGenerator.initialize(keyLengthBits);
65          result = keyPairGenerator.generateKeyPair().getPrivate();
66          cachedKeys.put(cacheKey, result);
67        }
68      } else if ("DSA".equals(keyAlgorithm)) {
69        DSAPrivateKeySpec originalKeySpec =
70            keyFactory.getKeySpec(originalPrivateKey, DSAPrivateKeySpec.class);
71        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(keyAlgorithm);
72        keyPairGenerator.initialize(new DSAParameterSpec(
73            originalKeySpec.getP(), originalKeySpec.getQ(), originalKeySpec.getG()));
74        result = keyPairGenerator.generateKeyPair().getPrivate();
75      } else if ("EC".equals(keyAlgorithm)) {
76        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(keyAlgorithm);
77        keyPairGenerator.initialize(((ECPrivateKey) originalPrivateKey).getParams());
78        result = keyPairGenerator.generateKeyPair().getPrivate();
79      } else {
80        Assert.fail("Unsupported key algorithm: " + originalPrivateKey.getAlgorithm());
81        result = null;
82      }
83    } catch (GeneralSecurityException e) {
84      Assert.fail("Failed to generate private key: " + e);
85      result = null;
86    }
87
88    return result;
89  }
90}
91