xmltooling/encryption/impl/Decrypter.cpp

   1 /*
   2  *  Copyright 2001-2007 Internet2
   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 /**
  18  * Decrypter.cpp
  19  *
  20  * Methods for decrypting XMLObjects and other data.
  21  */
  22
  23 #include "internal.h"
  24 #include "encryption/Decrypter.h"
  25 #include "encryption/EncryptedKeyResolver.h"
  26 #include "security/Credential.h"
  27 #include "security/CredentialCriteria.h"
  28 #include "security/CredentialResolver.h"
  29
  30 #include <log4cpp/Category.hh>
  31 #include <xsec/enc/XSECCryptoException.hpp>
  32 #include <xsec/framework/XSECException.hpp>
  33 #include <xsec/framework/XSECAlgorithmMapper.hpp>
  34 #include <xsec/framework/XSECAlgorithmHandler.hpp>
  35 #include <xsec/xenc/XENCEncryptedData.hpp>
  36 #include <xsec/xenc/XENCEncryptedKey.hpp>
  37
  38 using namespace xmlencryption;
  39 using namespace xmlsignature;
  40 using namespace xmltooling;
  41 using namespace std;
  42
  43 Decrypter::~Decrypter()
  44 {
  45     if (m_cipher)
  46         XMLToolingInternalConfig::getInternalConfig().m_xsecProvider->releaseCipher(m_cipher);
  47 }
  48
  49 DOMDocumentFragment* Decrypter::decryptData(const EncryptedData& encryptedData, XSECCryptoKey* key)
  50 {
  51     if (encryptedData.getDOM()==NULL)
  52         throw DecryptionException("The object must be marshalled before decryption.");
  53
  54     // We can reuse the cipher object if the document hasn't changed.
  55
  56     if (m_cipher && m_cipher->getDocument()!=encryptedData.getDOM()->getOwnerDocument()) {
  57         XMLToolingInternalConfig::getInternalConfig().m_xsecProvider->releaseCipher(m_cipher);
  58         m_cipher=NULL;
  59     }
  60
  61     if (!m_cipher)
  62         m_cipher=XMLToolingInternalConfig::getInternalConfig().m_xsecProvider->newCipher(encryptedData.getDOM()->getOwnerDocument());
  63
  64     try {
  65         m_cipher->setKey(key->clone());
  66         DOMNode* ret=m_cipher->decryptElementDetached(encryptedData.getDOM());
  67         if (ret->getNodeType()!=DOMNode::DOCUMENT_FRAGMENT_NODE) {
  68             ret->release();
  69             throw DecryptionException("Decryption operation did not result in DocumentFragment.");
  70         }
  71         return static_cast<DOMDocumentFragment*>(ret);
  72     }
  73     catch(XSECException& e) {
  74         auto_ptr_char temp(e.getMsg());
  75         throw DecryptionException(string("XMLSecurity exception while decrypting: ") + temp.get());
  76     }
  77     catch(XSECCryptoException& e) {
  78         throw DecryptionException(string("XMLSecurity exception while decrypting: ") + e.getMsg());
  79     }
  80 }
  81
  82 DOMDocumentFragment* Decrypter::decryptData(const EncryptedData& encryptedData, const XMLCh* recipient)
  83 {
  84     if (!m_credResolver)
  85         throw DecryptionException("No CredentialResolver supplied to provide decryption keys.");
  86
  87     // Resolve a decryption key directly.
  88     vector<const Credential*> creds;
  89     if (m_criteria) {
  90         m_criteria->setUsage(CredentialCriteria::ENCRYPTION_CREDENTIAL);
  91         m_criteria->setKeyInfo(encryptedData.getKeyInfo());
  92         const EncryptionMethod* meth = encryptedData.getEncryptionMethod();
  93         if (meth) {
  94             auto_ptr_char alg(meth->getAlgorithm());
  95             m_criteria->setKeyAlgorithm(alg.get());
  96         }
  97         m_credResolver->resolve(creds,m_criteria);
  98     }
  99     else {
 100         CredentialCriteria criteria;
 101         criteria.setUsage(CredentialCriteria::ENCRYPTION_CREDENTIAL);
 102         criteria.setKeyInfo(encryptedData.getKeyInfo());
 103         const EncryptionMethod* meth = encryptedData.getEncryptionMethod();
 104         if (meth) {
 105             auto_ptr_char alg(meth->getAlgorithm());
 106             criteria.setKeyAlgorithm(alg.get());
 107         }
 108         m_credResolver->resolve(creds,&criteria);
 109     }
 110
 111     // Loop over them and try each one.
 112     XSECCryptoKey* key;
 113     for (vector<const Credential*>::const_iterator cred = creds.begin(); cred!=creds.end(); ++cred) {
 114         try {
 115             key = (*cred)->getPrivateKey();
 116             if (!key)
 117                 continue;
 118             return decryptData(encryptedData, key);
 119         }
 120         catch(DecryptionException& ex) {
 121             log4cpp::Category::getInstance(XMLTOOLING_LOGCAT".Decrypter").warn(ex.what());
 122         }
 123     }
 124
 125     // We need to find an encrypted decryption key somewhere. We'll need the underlying algorithm...
 126     const XMLCh* algorithm=
 127         encryptedData.getEncryptionMethod() ? encryptedData.getEncryptionMethod()->getAlgorithm() : NULL;
 128     if (!algorithm)
 129         throw DecryptionException("No EncryptionMethod/@Algorithm set, key decryption cannot proceed.");
 130
 131     // Check for external resolver.
 132     const EncryptedKey* encKey=NULL;
 133     if (m_EKResolver)
 134         encKey = m_EKResolver->resolveKey(encryptedData, recipient);
 135     else {
 136         EncryptedKeyResolver ekr;
 137         encKey = ekr.resolveKey(encryptedData, recipient);
 138     }
 139
 140     if (!encKey)
 141         throw DecryptionException("Unable to locate an encrypted key.");
 142
 143     auto_ptr<XSECCryptoKey> keywrapper(decryptKey(*encKey, algorithm));
 144     if (!keywrapper.get())
 145         throw DecryptionException("Unable to decrypt the encrypted key.");
 146     return decryptData(encryptedData, keywrapper.get());
 147 }
 148
 149 XSECCryptoKey* Decrypter::decryptKey(const EncryptedKey& encryptedKey, const XMLCh* algorithm)
 150 {
 151     if (!m_credResolver)
 152         throw DecryptionException("No CredentialResolver supplied to provide decryption keys.");
 153
 154     if (encryptedKey.getDOM()==NULL)
 155         throw DecryptionException("The object must be marshalled before decryption.");
 156
 157     // We can reuse the cipher object if the document hasn't changed.
 158
 159     if (m_cipher && m_cipher->getDocument()!=encryptedKey.getDOM()->getOwnerDocument()) {
 160         XMLToolingInternalConfig::getInternalConfig().m_xsecProvider->releaseCipher(m_cipher);
 161         m_cipher=NULL;
 162     }
 163
 164     if (!m_cipher)
 165         m_cipher=XMLToolingInternalConfig::getInternalConfig().m_xsecProvider->newCipher(encryptedKey.getDOM()->getOwnerDocument());
 166
 167     // Resolve key decryption key. We can't loop over possible credentials because
 168     // we can't tell a valid decrypt from an invalid one.
 169     const Credential* cred=NULL;
 170     if (m_criteria) {
 171         m_criteria->setUsage(CredentialCriteria::ENCRYPTION_CREDENTIAL);
 172         m_criteria->setKeyInfo(encryptedKey.getKeyInfo());
 173         const EncryptionMethod* meth = encryptedKey.getEncryptionMethod();
 174         if (meth) {
 175             auto_ptr_char alg(meth->getAlgorithm());
 176             m_criteria->setKeyAlgorithm(alg.get());
 177         }
 178         cred = m_credResolver->resolve(m_criteria);
 179     }
 180     else {
 181         CredentialCriteria criteria;
 182         criteria.setUsage(CredentialCriteria::ENCRYPTION_CREDENTIAL);
 183         criteria.setKeyInfo(encryptedKey.getKeyInfo());
 184         const EncryptionMethod* meth = encryptedKey.getEncryptionMethod();
 185         if (meth) {
 186             auto_ptr_char alg(meth->getAlgorithm());
 187             criteria.setKeyAlgorithm(alg.get());
 188         }
 189         cred = m_credResolver->resolve(&criteria);
 190     }
 191     if (!cred || !cred->getPrivateKey())
 192         throw DecryptionException("Unable to resolve a key decryption key.");
 193
 194     try {
 195         m_cipher->setKEK(cred->getPrivateKey()->clone());
 196         XMLByte buffer[1024];
 197         memset(buffer,0,sizeof(buffer));
 198         int keySize = m_cipher->decryptKey(encryptedKey.getDOM(), buffer, 1024);
 199         if (keySize<=0)
 200             throw DecryptionException("Unable to decrypt key.");
 201
 202         // Try to map the key.
 203         XSECAlgorithmHandler* handler = XSECPlatformUtils::g_algorithmMapper->mapURIToHandler(algorithm);
 204         if (handler != NULL)
 205             return handler->createKeyForURI(algorithm, buffer, keySize);
 206         throw DecryptionException("Unrecognized algorithm, could not build object around decrypted key.");
 207     }
 208     catch(XSECException& e) {
 209         auto_ptr_char temp(e.getMsg());
 210         throw DecryptionException(string("XMLSecurity exception while decrypting key: ") + temp.get());
 211     }
 212     catch(XSECCryptoException& e) {
 213         throw DecryptionException(string("XMLSecurity exception while decrypting key: ") + e.getMsg());
 214     }
 215 }