/**
    * Copyright 2005-2012 The Kuali Foundation
    *
    * Licensed under the Educational Community License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    * http://www.opensource.org/licenses/ecl2.php
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.kuali.rice.ksb.security.service.impl;
  
  import java.io.IOException;
  import java.security.GeneralSecurityException;
  import java.security.KeyException;
  import java.security.PublicKey;
  import java.security.Signature;
  import java.security.cert.Certificate;
  import java.security.cert.CertificateException;
  
  import org.kuali.rice.core.api.resourceloader.GlobalResourceLoader;
  import org.kuali.rice.ksb.security.admin.service.JavaSecurityManagementService;
  import org.kuali.rice.ksb.security.service.DigitalSignatureService;
  import org.kuali.rice.ksb.util.KSBConstants;
  
  public class DigitalSignatureServiceImpl implements DigitalSignatureService {
  
  	public Signature getSignatureForSigning() throws IOException, GeneralSecurityException {
  		Signature signature = getSignature();
  		signature.initSign(getJavaSecurityManagementService().getModulePrivateKey());
  		return signature;
  	}
  
      public Signature getSignatureForVerification(String verificationAlias) throws IOException, GeneralSecurityException {
          Certificate cert = getJavaSecurityManagementService().getCertificate(verificationAlias);
          return getSignatureForVerification(cert);
      }
  
      public Signature getSignatureForVerification(Certificate certificate) throws IOException, GeneralSecurityException {
          if (certificate == null) {
              throw new CertificateException("Could not find certificate");
          }
          PublicKey publicKey = certificate.getPublicKey();
          if (publicKey == null) {
              throw new KeyException("Could not find the public key from valid certificate");
          }
          Signature signature = getSignature();
          signature.initVerify(publicKey);
          return signature;
      }
      
  	protected Signature getSignature() throws GeneralSecurityException {
  		return Signature.getInstance(getJavaSecurityManagementService().getModuleSignatureAlgorithm());
  	}
  	
  	protected JavaSecurityManagementService getJavaSecurityManagementService() {
  		return (JavaSecurityManagementService)GlobalResourceLoader.getService(KSBConstants.ServiceNames.JAVA_SECURITY_MANAGEMENT_SERVICE);
  	}
  
  
  }