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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  
21  import org.opensaml.xml.security.credential.Credential;
22  import org.opensaml.xml.security.keyinfo.KeyInfoCredentialContext;
23  import org.opensaml.xml.security.keyinfo.KeyInfoProvider;
24  import org.opensaml.xml.security.keyinfo.KeyInfoResolutionContext;
25  
26  /**
27   * Abstract super class for {@link KeyInfoProvider} implementations.
28   */
29  public abstract class AbstractKeyInfoProvider implements KeyInfoProvider {
30      
31      /**
32       * Utility method to extract any key that might be present in the specified Credential.
33       * 
34       * @param cred the Credential to evaluate
35       * @return the Key contained in the credential, or null if it does not contain a key.
36       */
37      protected Key extractKeyValue(Credential cred) {
38          if (cred == null) {
39              return null;
40          }
41          if (cred.getPublicKey() != null) {
42              return cred.getPublicKey();
43          } 
44          // This could happen if key is derived, e.g. key agreement, etc
45          if (cred.getSecretKey() != null) {
46              return cred.getSecretKey();
47          }
48          // Perhaps unlikely, but go ahead and check
49          if (cred.getPrivateKey() != null) {
50              return cred.getPrivateKey(); 
51          }
52          return null;
53      }
54      
55      /**
56       * Build a credential context based on the current KeyInfo context, for return 
57       * in a resolved credential.
58       * 
59       * @param kiContext the current KeyInfo resolution context
60       * 
61       * @return a new KeyInfo credential context
62       */
63      protected KeyInfoCredentialContext buildCredentialContext(KeyInfoResolutionContext kiContext) {
64          // Simple for now, might do other stuff later.
65          // Just want to provide a single place to build credential contexts for
66          // a provider.
67          if (kiContext != null) {
68              return new KeyInfoCredentialContext(kiContext.getKeyInfo());
69          } else {
70              return null;
71          }
72      }
73  
74  }