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1   /*
2    * Copyright [2007] [University Corporation for Advanced Internet Development, Inc.]
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  
17  package org.opensaml.xml.security.keyinfo.provider;
18  
19  import java.security.Key;
20  import java.util.HashSet;
21  import java.util.Set;
22  
23  import org.opensaml.xml.security.credential.Credential;
24  import org.opensaml.xml.security.keyinfo.KeyInfoCredentialContext;
25  import org.opensaml.xml.security.keyinfo.KeyInfoProvider;
26  import org.opensaml.xml.security.keyinfo.KeyInfoResolutionContext;
27  
28  /**
29   * Abstract super class for {@link KeyInfoProvider} implementations.
30   */
31  public abstract class AbstractKeyInfoProvider implements KeyInfoProvider {
32      
33      /**
34       * Utility method to extract any key that might be present in the specified Credential.
35       * 
36       * @param cred the Credential to evaluate
37       * @return the Key contained in the credential, or null if it does not contain a key.
38       */
39      protected Key extractKeyValue(Credential cred) {
40          if (cred == null) {
41              return null;
42          }
43          if (cred.getPublicKey() != null) {
44              return cred.getPublicKey();
45          } 
46          // This could happen if key is derived, e.g. key agreement, etc
47          if (cred.getSecretKey() != null) {
48              return cred.getSecretKey();
49          }
50          // Perhaps unlikely, but go ahead and check
51          if (cred.getPrivateKey() != null) {
52              return cred.getPrivateKey(); 
53          }
54          return null;
55      }
56      
57      /**
58       * Convenience method to create a credential set out of a single credential.
59       * 
60       * @param credential the credential to return
61       * @return a set containing the supplied credential
62       */
63      protected Set<Credential> singletonSet(Credential credential) {
64          HashSet<Credential> set = new HashSet<Credential>(1);
65          set.add(credential);
66          return set;
67      }
68      
69      /**
70       * Build a credential context based on the current KeyInfo context, for return 
71       * in a resolved credential.
72       * 
73       * @param kiContext the current KeyInfo resolution context
74       * 
75       * @return a new KeyInfo credential context
76       */
77      protected KeyInfoCredentialContext buildCredentialContext(KeyInfoResolutionContext kiContext) {
78          // Simple for now, might do other stuff later.
79          // Just want to provide a single place to build credential contexts for
80          // a provider.
81          if (kiContext != null) {
82              return new KeyInfoCredentialContext(kiContext.getKeyInfo());
83          } else {
84              return null;
85          }
86      }
87  
88  }