mail.SignedDataProcessor.java Source code

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Here is the source code for mail.SignedDataProcessor.java

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/**************************************************************************
    
  Copyright [2009] [CrypTool Team]
    
  This file is part of CrypTool.
    
  Licensed under the Apache 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.apache.org/licenses/LICENSE-2.0
    
  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 mail;

import java.security.cert.CertStore;
import java.security.cert.PKIXCertPathBuilderResult;
import java.security.cert.X509CertSelector;
import java.security.cert.X509Certificate;
import java.util.Iterator;

import org.bouncycastle.cms.CMSSignedData;
import org.bouncycastle.cms.SignerInformation;
import org.bouncycastle.cms.SignerInformationStore;

import utils.Utils;

/**
 * Base class for signed examples.
 */
public class SignedDataProcessor {
    /**
     * Return a boolean array representing keyUsage with digitalSignature set.
     */
    static boolean[] getKeyUsageForSignature() {
        boolean[] val = new boolean[9];

        val[0] = true;

        return val;
    }

    /**
     * Take a CMS SignedData message and a trust anchor and determine if
     * the message is signed with a valid signature from a end entity
     * entity certificate recognized by the trust anchor rootCert.
     */
    @SuppressWarnings("unchecked")
    public static boolean isValid(CMSSignedData signedData, X509Certificate rootCert) throws Exception {
        CertStore certsAndCRLs = signedData.getCertificatesAndCRLs("Collection", "BC");
        SignerInformationStore signers = signedData.getSignerInfos();
        Iterator it = signers.getSigners().iterator();

        if (it.hasNext()) {
            SignerInformation signer = (SignerInformation) it.next();
            X509CertSelector signerConstraints = signer.getSID();

            signerConstraints.setKeyUsage(getKeyUsageForSignature());

            PKIXCertPathBuilderResult result = Utils.buildPath(rootCert, signer.getSID(), certsAndCRLs);

            return signer.verify(result.getPublicKey(), "BC");
        }

        return false;
    }
}