def _decode_subject_key_identifier(backend, asn1_string):
    asn1_string = backend._ffi.cast("ASN1_OCTET_STRING *", asn1_string)
    asn1_string = backend._ffi.gc(
        asn1_string, backend._lib.ASN1_OCTET_STRING_free
    )
    return x509.SubjectKeyIdentifier(
        backend._ffi.buffer(asn1_string.data, asn1_string.length)[:]
    ) 

def _decode_subject_key_identifier(backend, asn1_string):
    asn1_string = backend._ffi.cast("ASN1_OCTET_STRING *", asn1_string)
    asn1_string = backend._ffi.gc(
        asn1_string, backend._lib.ASN1_OCTET_STRING_free
    )
    return x509.SubjectKeyIdentifier(
        backend._ffi.buffer(asn1_string.data, asn1_string.length)[:]
    ) 

def _decode_subject_key_identifier(backend, asn1_string):
    asn1_string = backend._ffi.cast("ASN1_OCTET_STRING *", asn1_string)
    asn1_string = backend._ffi.gc(
        asn1_string, backend._lib.ASN1_OCTET_STRING_free
    )
    return x509.SubjectKeyIdentifier(
        backend._ffi.buffer(asn1_string.data, asn1_string.length)[:]
    ) 

def _decode_subject_key_identifier(backend, asn1_string):
    asn1_string = backend._ffi.cast("ASN1_OCTET_STRING *", asn1_string)
    asn1_string = backend._ffi.gc(
        asn1_string, backend._lib.ASN1_OCTET_STRING_free
    )
    return x509.SubjectKeyIdentifier(
        backend._ffi.buffer(asn1_string.data, asn1_string.length)[:]
    ) 

def _decode_subject_key_identifier(backend, asn1_string):
    asn1_string = backend._ffi.cast("ASN1_OCTET_STRING *", asn1_string)
    asn1_string = backend._ffi.gc(
        asn1_string, backend._lib.ASN1_OCTET_STRING_free
    )
    return x509.SubjectKeyIdentifier(
        backend._ffi.buffer(asn1_string.data, asn1_string.length)[:]
    ) 

def _decode_subject_key_identifier(backend, asn1_string):
    asn1_string = backend._ffi.cast("ASN1_OCTET_STRING *", asn1_string)
    asn1_string = backend._ffi.gc(
        asn1_string, backend._lib.ASN1_OCTET_STRING_free
    )
    return x509.SubjectKeyIdentifier(
        backend._ffi.buffer(asn1_string.data, asn1_string.length)[:]
    ) 

def subject_key_identifier(self):
        """The :py:class:`~django_ca.extensions.SubjectKeyIdentifier` extension, or ``None`` if it doesn't
        exist."""
        ext = self.get_x509_extension(ExtensionOID.SUBJECT_KEY_IDENTIFIER)
        if ext is not None:
            return SubjectKeyIdentifier(ext) 

def get_authority_key_identifier(self):
        """Return the AuthorityKeyIdentifier extension used in certificates signed by this CA."""

        try:
            ski = self.x509.extensions.get_extension_for_class(x509.SubjectKeyIdentifier)
        except x509.ExtensionNotFound:
            return x509.AuthorityKeyIdentifier.from_issuer_public_key(self.x509.public_key())
        else:
            return x509.AuthorityKeyIdentifier.from_issuer_subject_key_identifier(ski.value) 

def from_other(self, value):
        if isinstance(value, SubjectKeyIdentifier):
            self.critical = self.default_critical
            self.from_subject_key_identifier(value)
            self._test_value()
        else:
            super().from_other(value) 

def extension_type(self):
        return x509.SubjectKeyIdentifier(digest=self.value) 

def from_other(self, value):
        if isinstance(value, x509.SubjectKeyIdentifier):
            self.critical = self.default_critical
            self.value = value.digest
            self._test_value()
        else:
            super().from_other(value) 

def _decode_subject_key_identifier(backend, asn1_string):
    asn1_string = backend._ffi.cast("ASN1_OCTET_STRING *", asn1_string)
    asn1_string = backend._ffi.gc(
        asn1_string, backend._lib.ASN1_OCTET_STRING_free
    )
    return x509.SubjectKeyIdentifier(
        backend._ffi.buffer(asn1_string.data, asn1_string.length)[:]
    ) 

def _decode_subject_key_identifier(backend, asn1_string):
    asn1_string = backend._ffi.cast("ASN1_OCTET_STRING *", asn1_string)
    asn1_string = backend._ffi.gc(
        asn1_string, backend._lib.ASN1_OCTET_STRING_free
    )
    return x509.SubjectKeyIdentifier(
        backend._ffi.buffer(asn1_string.data, asn1_string.length)[:]
    ) 

def _decode_subject_key_identifier(backend, asn1_string):
    asn1_string = backend._ffi.cast("ASN1_OCTET_STRING *", asn1_string)
    asn1_string = backend._ffi.gc(
        asn1_string, backend._lib.ASN1_OCTET_STRING_free
    )
    return x509.SubjectKeyIdentifier(
        backend._ffi.buffer(asn1_string.data, asn1_string.length)[:]
    ) 

def extensions(self):
        # setup default values
        return_extensions = {"sub_alt_names": {"names": []}}

        try:
            for extension in self.parsed_cert.extensions:
                value = extension.value
                if isinstance(value, x509.BasicConstraints):
                    return_extensions["basic_constraints"] = value

                elif isinstance(value, x509.SubjectAlternativeName):
                    return_extensions["sub_alt_names"]["names"] = value

                elif isinstance(value, x509.ExtendedKeyUsage):
                    return_extensions["extended_key_usage"] = value

                elif isinstance(value, x509.KeyUsage):
                    return_extensions["key_usage"] = value

                elif isinstance(value, x509.SubjectKeyIdentifier):
                    return_extensions["subject_key_identifier"] = {"include_ski": True}

                elif isinstance(value, x509.AuthorityInformationAccess):
                    return_extensions["certificate_info_access"] = {"include_aia": True}

                elif isinstance(value, x509.AuthorityKeyIdentifier):
                    aki = {"use_key_identifier": False, "use_authority_cert": False}

                    if value.key_identifier:
                        aki["use_key_identifier"] = True

                    if value.authority_cert_issuer:
                        aki["use_authority_cert"] = True

                    return_extensions["authority_key_identifier"] = aki

                elif isinstance(value, x509.CRLDistributionPoints):
                    return_extensions["crl_distribution_points"] = {
                        "include_crl_dp": value
                    }

                # TODO: Not supporting custom OIDs yet. https://github.com/Netflix/lemur/issues/665
                else:
                    current_app.logger.warning(
                        "Custom OIDs not yet supported for clone operation."
                    )
        except InvalidCodepoint as e:
            sentry.captureException()
            current_app.logger.warning(
                "Unable to parse extensions due to underscore in dns name"
            )
        except ValueError as e:
            sentry.captureException()
            current_app.logger.warning("Unable to parse")
            current_app.logger.exception(e)

        return return_extensions