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25 
26 package sun.security.ssl;
27 
28 import java.security.*;
29 
30 /**
31  * The "KeyManager" for ephemeral RSA keys. Ephemeral DH and ECDH keys
32  * are handled by the DHCrypt and ECDHCrypt classes, respectively.
33  *
34  * @author  Andreas Sterbenz
35  */
36 final class EphemeralKeyManager {
37 
38     // indices for the keys array below
39     private static final int INDEX_RSA512 = 0;
40     private static final int INDEX_RSA1024 = 1;
41 
42     /*
43      * Current cached RSA KeyPairs. Elements are never null.
44      * Indexed via the constants above.
45      */
46     private final EphemeralKeyPair[] keys = new EphemeralKeyPair[] {
47         new EphemeralKeyPair(null),
48         new EphemeralKeyPair(null),
49     };
50 
EphemeralKeyManager()51     EphemeralKeyManager() {
52         // empty
53     }
54 
55     /*
56      * Get a temporary RSA KeyPair.
57      */
getRSAKeyPair(boolean export, SecureRandom random)58     KeyPair getRSAKeyPair(boolean export, SecureRandom random) {
59         int length, index;
60         if (export) {
61             length = 512;
62             index = INDEX_RSA512;
63         } else {
64             length = 1024;
65             index = INDEX_RSA1024;
66         }
67 
68         synchronized (keys) {
69             KeyPair kp = keys[index].getKeyPair();
70             if (kp == null) {
71                 try {
72                     KeyPairGenerator kgen = JsseJce.getKeyPairGenerator("RSA");
73                     kgen.initialize(length, random);
74                     keys[index] = new EphemeralKeyPair(kgen.genKeyPair());
75                     kp = keys[index].getKeyPair();
76                 } catch (Exception e) {
77                     // ignore
78                 }
79             }
80             return kp;
81         }
82     }
83 
84     /**
85      * Inner class to handle storage of ephemeral KeyPairs.
86      */
87     private static class EphemeralKeyPair {
88 
89         // maximum number of times a KeyPair is used
90         private static final int MAX_USE = 200;
91 
92         // maximum time interval in which the keypair is used (1 hour in ms)
93         private static final long USE_INTERVAL = 3600*1000;
94 
95         private KeyPair keyPair;
96         private int uses;
97         private long expirationTime;
98 
EphemeralKeyPair(KeyPair keyPair)99         private EphemeralKeyPair(KeyPair keyPair) {
100             this.keyPair = keyPair;
101             expirationTime = System.currentTimeMillis() + USE_INTERVAL;
102         }
103 
104         /*
105          * Check if the KeyPair can still be used.
106          */
isValid()107         private boolean isValid() {
108             return (keyPair != null) && (uses < MAX_USE)
109                    && (System.currentTimeMillis() < expirationTime);
110         }
111 
112         /*
113          * Return the KeyPair or null if it is invalid.
114          */
getKeyPair()115         private KeyPair getKeyPair() {
116             if (isValid() == false) {
117                 keyPair = null;
118                 return null;
119             }
120             uses++;
121             return keyPair;
122         }
123     }
124 }
125