How do I use python to create digital signature of string? I want to add the certificates and CRLs contained in the given CertStore to the pool that will be included in the encoded signature block (java bouncy castle's CMSSignedDataGenerator.addCertificatesAndCRLs does this job). Below is a java code I want to replicate in python.

package pkcs7gen;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.security.KeyStore;
import java.security.PrivateKey;
import java.security.Security;
import java.security.cert.CertStore;
import java.security.cert.Certificate;
import java.security.cert.CollectionCertStoreParameters;
import java.security.cert.X509Certificate;
import java.util.ArrayList;
import java.util.Enumeration;

import org.bouncycastle.cms.CMSProcessableByteArray;
import org.bouncycastle.cms.CMSSignedData;
import org.bouncycastle.cms.CMSSignedDataGenerator;
import org.bouncycastle.cms.CMSTypedData;
import org.bouncycastle.util.encoders.Base64;
import org.springframework.stereotype.Service;

@Service
public class Pkcs7gen {


    final String SIGNATUREALGO = "SHA1withRSA";

    byte[] signPkcs7(final byte[] content, final CMSSignedDataGenerator generator) throws Exception {

        CMSTypedData cmsdata = new CMSProcessableByteArray(content);
        CMSSignedData signeddata = generator.generate(cmsdata, true);
        return signeddata.getEncoded();
    }

    public static void main(String[] args) {
        try {
            String data = getSignature(args[0]);
            System.out.println(data);
        }
        catch (Exception exc) {
            // TODO: handle exception
        }
    }

    public static String getSignature (String content) throws Exception{

        KeyStore keystore = KeyStore.getInstance("jks");
        InputStream input = new FileInputStream("./keystore.jks");
        try {
            char[] password= "password".toCharArray();
            keystore.load(input, password);
        } catch (IOException e) {
        } finally {


        Enumeration e = keystore.aliases();
        String alias = "";

        if(e!=null)
        {
            while (e.hasMoreElements())
            {
                String  n = (String)e.nextElement();
                if (keystore.isKeyEntry(n))
                {
                    alias = n;
                }
            }
        }
        PrivateKey privateKey=(PrivateKey) keystore.getKey(alias, "password".toCharArray());

        X509Certificate myPubCert=(X509Certificate) keystore.getCertificate(alias);
        byte[] dataToSign=content.getBytes();
        CMSSignedDataGenerator sgen = new CMSSignedDataGenerator();
        Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider ());
        sgen.addSigner(privateKey, myPubCert,CMSSignedDataGenerator.DIGEST_SHA1);
        Certificate[] certChain =keystore.getCertificateChain(alias);
        ArrayList certList = new ArrayList();
        CertStore certs = null;
        for (int i=0; i < certChain.length; i++)
            certList.add(certChain[i]);
        sgen.addCertificatesAndCRLs(CertStore.getInstance("Collection", new CollectionCertStoreParameters(certList), "BC"));
        CMSSignedData csd = sgen.generate(new CMSProcessableByteArray(dataToSign),true, "BC");
        byte[] signedData = csd.getEncoded();
        byte[] signedData64 = Base64.encode(signedData);
        return new String(signedData64);
    }

}
}