Return a list of DER coded X.509 certificates from the v3 signature block

def get_certificates_der_v3(self):
        """
        Return a list of DER coded X.509 certificates from the v3 signature block
        """

        if self._v3_signing_data == None:
            self.parse_v3_signing_block()

        certs = []
        for signed_data in [signer.signed_data for signer in self._v3_signing_data]:
            for cert in signed_data.certificates:
                certs.append(cert)

        return certs