Java BC1.47: Need to extract signer's X509CertificateObject from a CMSSignedData object

Question

I'm trying to extract the signer's X509CertificateObject from a CMSSignedData object using java Bouncy Castle 1.47. So far I have only been able to extract an org.bouncycastle.asn1.x509.Certificate object. How do I get a X509CertificateObject from this? Thanks a lot!

public static X509CertificateObject extractSignersCert(CMSSignedData cmsSignedData)
    throws Exception
{
    SignerInformationStore signerInfoStore;
    SignerInformation signerInfo;
    Store certStore;
    Collection certCollection;
    X509CertificateHolder x509CertHolder;
    X509Certificate cert;
    X509CertificateObject certObj;
    JcaX509CertificateConverter certConverter;

    signerInfoStore = cmsSignedData.getSignerInfos();
    signerInfo = (SignerInformation) signerInfoStore.getSigners().iterator().next();

    certStore = cmsSignedData.getCertificates();
    certCollection = certStore.getMatches(signerInfo.getSID());
    x509CertHolder = (X509CertificateHolder) certCollection.iterator().next();

    certConverter = new JcaX509CertificateConverter();
    certConverter.setProvider("BC");

    cert = certConverter.getCertificate(x509CertHolder);
    certObj = (X509CertificateObject) cert;

    return certObj;
}

Answer 1

Finally found a solution based on this post. The trick is to use a JcaX509CertificateConverter() and feed it with the X509CertificateHolder you can easily get from the CMSSignedData. Works just fine.

Answer 2

You can use this method.

/**
 * Get all x509 certificates from p7s File(.p7s or .p7b) Base64 format
 * @param p7sFileName
 * @return list of x509 certificates
 */
public static ArrayList<X509Certificate> getCertificates(final String p7sFileName){

    final ArrayList<X509Certificate> certListResult = new ArrayList<X509Certificate>();

    try {

        BufferedReader br = new BufferedReader(new FileReader(p7sFileName));
        StringBuilder str = new StringBuilder();
        br.readLine();
        while(br.ready()){

            String s = br.readLine();
            if(s.startsWith("-----END PKCS7-----"))
                break;
            else str.append(s);

        }

        byte[] data = Base64.decode(str.toString().getBytes());

        CMSSignedData s = new CMSSignedData(data);
        Store   certStore = s.getCertificates();

        JcaX509CertificateConverter converter = new JcaX509CertificateConverter();

        @SuppressWarnings("unchecked")
        ArrayList<X509CertificateHolder> certificateHolders = (ArrayList<X509CertificateHolder>)certStore.getMatches(null); 

        for(X509CertificateHolder holder: certificateHolders){

                X509Certificate cert = converter.getCertificate(holder);
                certListResult.add(cert);

            }

    } catch (FileNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (CMSException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (CertificateException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    return certListResult;

}