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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.KeyException;
20  import java.security.PublicKey;
21  import java.util.Collection;
22  
23  import org.opensaml.xml.XMLObject;
24  import org.opensaml.xml.security.CriteriaSet;
25  import org.opensaml.xml.security.SecurityException;
26  import org.opensaml.xml.security.credential.BasicCredential;
27  import org.opensaml.xml.security.credential.Credential;
28  import org.opensaml.xml.security.credential.CredentialContext;
29  import org.opensaml.xml.security.criteria.KeyAlgorithmCriteria;
30  import org.opensaml.xml.security.keyinfo.KeyInfoCredentialResolver;
31  import org.opensaml.xml.security.keyinfo.KeyInfoHelper;
32  import org.opensaml.xml.security.keyinfo.KeyInfoProvider;
33  import org.opensaml.xml.security.keyinfo.KeyInfoResolutionContext;
34  import org.opensaml.xml.signature.DSAKeyValue;
35  import org.opensaml.xml.signature.KeyValue;
36  import org.slf4j.Logger;
37  import org.slf4j.LoggerFactory;
38  
39  /**
40   * Implementation of {@link KeyInfoProvider} which supports {@link DSAKeyValue}.
41   */
42  public class DSAKeyValueProvider extends AbstractKeyInfoProvider {
43      
44      /** Class logger. */
45      private final Logger log = LoggerFactory.getLogger(DSAKeyValueProvider.class);
46  
47      /** {@inheritDoc} */
48      public boolean handles(XMLObject keyInfoChild) {
49          return getDSAKeyValue(keyInfoChild) != null;
50      }
51  
52      /** {@inheritDoc} */
53      public Collection<Credential> process(KeyInfoCredentialResolver resolver, XMLObject keyInfoChild, 
54              CriteriaSet criteriaSet, KeyInfoResolutionContext kiContext) throws SecurityException {
55          
56          DSAKeyValue keyValue = getDSAKeyValue(keyInfoChild);
57          if (keyValue == null) {
58              return null;
59          }
60          
61          KeyAlgorithmCriteria algorithmCriteria = criteriaSet.get(KeyAlgorithmCriteria.class);
62          if (algorithmCriteria != null 
63                  && algorithmCriteria.getKeyAlgorithm() != null 
64                  && ! algorithmCriteria.getKeyAlgorithm().equals("DSA")) {
65              log.debug("Criteria specified non-DSA key algorithm, skipping");
66              return null;
67          }
68          
69          log.debug("Attempting to extract credential from a DSAKeyValue");
70          
71          PublicKey pubKey = null;
72          try {
73              //TODO deal with case of incomplete DSAParams, need hook to resolve those
74              pubKey = KeyInfoHelper.getDSAKey(keyValue);
75          } catch (KeyException e) {
76              log.error("Error extracting DSA key value", e);
77              throw new SecurityException("Error extracting DSA key value", e);
78          }
79          BasicCredential cred = new BasicCredential();
80          cred.setPublicKey(pubKey);
81          if (kiContext != null) {
82              cred.getKeyNames().addAll(kiContext.getKeyNames());
83          }
84          
85          CredentialContext credContext = buildCredentialContext(kiContext);
86          if (credContext != null) {
87              cred.getCredentalContextSet().add(credContext);
88          }
89          
90          log.debug("Credential successfully extracted from DSAKeyValue");
91          return singletonSet(cred);
92      }
93      
94      /**
95       * Get the DSAKeyValue from the passed XML object.
96       * 
97       * @param xmlObject an XML object, presumably either a {@link KeyValue} or an {@link DSAKeyValue}
98       * @return the DSAKeyValue which was found, or null if none
99       */
100     protected DSAKeyValue getDSAKeyValue(XMLObject xmlObject) {
101         if (xmlObject == null) {return null; }
102         
103         if (xmlObject instanceof DSAKeyValue) {
104             return (DSAKeyValue) xmlObject;
105         }
106         
107         if (xmlObject instanceof KeyValue) {
108             return ((KeyValue) xmlObject).getDSAKeyValue();
109         }
110         return null;
111     }
112 }