Edit File: crl.py
# coding: utf-8 """ ASN.1 type classes for certificate revocation lists (CRL). Exports the following items: - CertificateList() Other type classes are defined that help compose the types listed above. """ from __future__ import unicode_literals, division, absolute_import, print_function import hashlib from .algos import SignedDigestAlgorithm from .core import ( Boolean, Enumerated, GeneralizedTime, Integer, ObjectIdentifier, OctetBitString, ParsableOctetString, Sequence, SequenceOf, ) from .x509 import ( AuthorityInfoAccessSyntax, AuthorityKeyIdentifier, CRLDistributionPoints, DistributionPointName, GeneralNames, Name, ReasonFlags, Time, ) # The structures in this file are taken from https://tools.ietf.org/html/rfc5280 class Version(Integer): _map = { 0: 'v1', 1: 'v2', 2: 'v3', } class IssuingDistributionPoint(Sequence): _fields = [ ('distribution_point', DistributionPointName, {'tag_type': 'explicit', 'tag': 0, 'optional': True}), ('only_contains_user_certs', Boolean, {'tag_type': 'implicit', 'tag': 1, 'default': False}), ('only_contains_ca_certs', Boolean, {'tag_type': 'implicit', 'tag': 2, 'default': False}), ('only_some_reasons', ReasonFlags, {'tag_type': 'implicit', 'tag': 3, 'optional': True}), ('indirect_crl', Boolean, {'tag_type': 'implicit', 'tag': 4, 'default': False}), ('only_contains_attribute_certs', Boolean, {'tag_type': 'implicit', 'tag': 5, 'default': False}), ] class TBSCertListExtensionId(ObjectIdentifier): _map = { '2.5.29.18': 'issuer_alt_name', '2.5.29.20': 'crl_number', '2.5.29.27': 'delta_crl_indicator', '2.5.29.28': 'issuing_distribution_point', '2.5.29.35': 'authority_key_identifier', '2.5.29.46': 'freshest_crl', '1.3.6.1.5.5.7.1.1': 'authority_information_access', } class TBSCertListExtension(Sequence): _fields = [ ('extn_id', TBSCertListExtensionId), ('critical', Boolean, {'default': False}), ('extn_value', ParsableOctetString), ] _oid_pair = ('extn_id', 'extn_value') _oid_specs = { 'issuer_alt_name': GeneralNames, 'crl_number': Integer, 'delta_crl_indicator': Integer, 'issuing_distribution_point': IssuingDistributionPoint, 'authority_key_identifier': AuthorityKeyIdentifier, 'freshest_crl': CRLDistributionPoints, 'authority_information_access': AuthorityInfoAccessSyntax, } class TBSCertListExtensions(SequenceOf): _child_spec = TBSCertListExtension class CRLReason(Enumerated): _map = { 0: 'unspecified', 1: 'key_compromise', 2: 'ca_compromise', 3: 'affiliation_changed', 4: 'superseded', 5: 'cessation_of_operation', 6: 'certificate_hold', 8: 'remove_from_crl', 9: 'privilege_withdrawn', 10: 'aa_compromise', } @property def human_friendly(self): """ :return: A unicode string with revocation description that is suitable to show to end-users. Starts with a lower case letter and phrased in such a way that it makes sense after the phrase "because of" or "due to". """ return { 'unspecified': 'an unspecified reason', 'key_compromise': 'a compromised key', 'ca_compromise': 'the CA being compromised', 'affiliation_changed': 'an affiliation change', 'superseded': 'certificate supersession', 'cessation_of_operation': 'a cessation of operation', 'certificate_hold': 'a certificate hold', 'remove_from_crl': 'removal from the CRL', 'privilege_withdrawn': 'privilege withdrawl', 'aa_compromise': 'the AA being compromised', }[self.native] class CRLEntryExtensionId(ObjectIdentifier): _map = { '2.5.29.21': 'crl_reason', '2.5.29.23': 'hold_instruction_code', '2.5.29.24': 'invalidity_date', '2.5.29.29': 'certificate_issuer', } class CRLEntryExtension(Sequence): _fields = [ ('extn_id', CRLEntryExtensionId), ('critical', Boolean, {'default': False}), ('extn_value', ParsableOctetString), ] _oid_pair = ('extn_id', 'extn_value') _oid_specs = { 'crl_reason': CRLReason, 'hold_instruction_code': ObjectIdentifier, 'invalidity_date': GeneralizedTime, 'certificate_issuer': GeneralNames, } class CRLEntryExtensions(SequenceOf): _child_spec = CRLEntryExtension class RevokedCertificate(Sequence): _fields = [ ('user_certificate', Integer), ('revocation_date', Time), ('crl_entry_extensions', CRLEntryExtensions, {'optional': True}), ] _processed_extensions = False _critical_extensions = None _crl_reason_value = None _invalidity_date_value = None _certificate_issuer_value = None _issuer_name = False def _set_extensions(self): """ Sets common named extensions to private attributes and creates a list of critical extensions """ self._critical_extensions = set() for extension in self['crl_entry_extensions']: name = extension['extn_id'].native attribute_name = '_%s_value' % name if hasattr(self, attribute_name): setattr(self, attribute_name, extension['extn_value'].parsed) if extension['critical'].native: self._critical_extensions.add(name) self._processed_extensions = True @property def critical_extensions(self): """ Returns a set of the names (or OID if not a known extension) of the extensions marked as critical :return: A set of unicode strings """ if not self._processed_extensions: self._set_extensions() return self._critical_extensions @property def crl_reason_value(self): """ This extension indicates the reason that a certificate was revoked. :return: None or a CRLReason object """ if self._processed_extensions is False: self._set_extensions() return self._crl_reason_value @property def invalidity_date_value(self): """ This extension indicates the suspected date/time the private key was compromised or the certificate became invalid. This would usually be before the revocation date, which is when the CA processed the revocation. :return: None or a GeneralizedTime object """ if self._processed_extensions is False: self._set_extensions() return self._invalidity_date_value @property def certificate_issuer_value(self): """ This extension indicates the issuer of the certificate in question, and is used in indirect CRLs. CRL entries without this extension are for certificates issued from the last seen issuer. :return: None or an x509.GeneralNames object """ if self._processed_extensions is False: self._set_extensions() return self._certificate_issuer_value @property def issuer_name(self): """ :return: None, or an asn1crypto.x509.Name object for the issuer of the cert """ if self._issuer_name is False: self._issuer_name = None if self.certificate_issuer_value: for general_name in self.certificate_issuer_value: if general_name.name == 'directory_name': self._issuer_name = general_name.chosen break return self._issuer_name class RevokedCertificates(SequenceOf): _child_spec = RevokedCertificate class TbsCertList(Sequence): _fields = [ ('version', Version, {'optional': True}), ('signature', SignedDigestAlgorithm), ('issuer', Name), ('this_update', Time), ('next_update', Time), ('revoked_certificates', RevokedCertificates, {'optional': True}), ('crl_extensions', TBSCertListExtensions, {'tag_type': 'explicit', 'tag': 0, 'optional': True}), ] class CertificateList(Sequence): _fields = [ ('tbs_cert_list', TbsCertList), ('signature_algorithm', SignedDigestAlgorithm), ('signature', OctetBitString), ] _processed_extensions = False _critical_extensions = None _issuer_alt_name_value = None _crl_number_value = None _delta_crl_indicator_value = None _issuing_distribution_point_value = None _authority_key_identifier_value = None _freshest_crl_value = None _authority_information_access_value = None _issuer_cert_urls = None _delta_crl_distribution_points = None _sha1 = None _sha256 = None def _set_extensions(self): """ Sets common named extensions to private attributes and creates a list of critical extensions """ self._critical_extensions = set() for extension in self['tbs_cert_list']['crl_extensions']: name = extension['extn_id'].native attribute_name = '_%s_value' % name if hasattr(self, attribute_name): setattr(self, attribute_name, extension['extn_value'].parsed) if extension['critical'].native: self._critical_extensions.add(name) self._processed_extensions = True @property def critical_extensions(self): """ Returns a set of the names (or OID if not a known extension) of the extensions marked as critical :return: A set of unicode strings """ if not self._processed_extensions: self._set_extensions() return self._critical_extensions @property def issuer_alt_name_value(self): """ This extension allows associating one or more alternative names with the issuer of the CRL. :return: None or an x509.GeneralNames object """ if self._processed_extensions is False: self._set_extensions() return self._issuer_alt_name_value @property def crl_number_value(self): """ This extension adds a monotonically increasing number to the CRL and is used to distinguish different versions of the CRL. :return: None or an Integer object """ if self._processed_extensions is False: self._set_extensions() return self._crl_number_value @property def delta_crl_indicator_value(self): """ This extension indicates a CRL is a delta CRL, and contains the CRL number of the base CRL that it is a delta from. :return: None or an Integer object """ if self._processed_extensions is False: self._set_extensions() return self._delta_crl_indicator_value @property def issuing_distribution_point_value(self): """ This extension includes information about what types of revocations and certificates are part of the CRL. :return: None or an IssuingDistributionPoint object """ if self._processed_extensions is False: self._set_extensions() return self._issuing_distribution_point_value @property def authority_key_identifier_value(self): """ This extension helps in identifying the public key with which to validate the authenticity of the CRL. :return: None or an AuthorityKeyIdentifier object """ if self._processed_extensions is False: self._set_extensions() return self._authority_key_identifier_value @property def freshest_crl_value(self): """ This extension is used in complete CRLs to indicate where a delta CRL may be located. :return: None or a CRLDistributionPoints object """ if self._processed_extensions is False: self._set_extensions() return self._freshest_crl_value @property def authority_information_access_value(self): """ This extension is used to provide a URL with which to download the certificate used to sign this CRL. :return: None or an AuthorityInfoAccessSyntax object """ if self._processed_extensions is False: self._set_extensions() return self._authority_information_access_value @property def issuer(self): """ :return: An asn1crypto.x509.Name object for the issuer of the CRL """ return self['tbs_cert_list']['issuer'] @property def authority_key_identifier(self): """ :return: None or a byte string of the key_identifier from the authority key identifier extension """ if not self.authority_key_identifier_value: return None return self.authority_key_identifier_value['key_identifier'].native @property def issuer_cert_urls(self): """ :return: A list of unicode strings that are URLs that should contain either an individual DER-encoded X.509 certificate, or a DER-encoded CMS message containing multiple certificates """ if self._issuer_cert_urls is None: self._issuer_cert_urls = [] if self.authority_information_access_value: for entry in self.authority_information_access_value: if entry['access_method'].native == 'ca_issuers': location = entry['access_location'] if location.name != 'uniform_resource_identifier': continue url = location.native if url.lower()[0:7] == 'http://': self._issuer_cert_urls.append(url) return self._issuer_cert_urls @property def delta_crl_distribution_points(self): """ Returns delta CRL URLs - only applies to complete CRLs :return: A list of zero or more DistributionPoint objects """ if self._delta_crl_distribution_points is None: self._delta_crl_distribution_points = [] if self.freshest_crl_value is not None: for distribution_point in self.freshest_crl_value: distribution_point_name = distribution_point['distribution_point'] # RFC 5280 indicates conforming CA should not use the relative form if distribution_point_name.name == 'name_relative_to_crl_issuer': continue # This library is currently only concerned with HTTP-based CRLs for general_name in distribution_point_name.chosen: if general_name.name == 'uniform_resource_identifier': self._delta_crl_distribution_points.append(distribution_point) return self._delta_crl_distribution_points @property def signature(self): """ :return: A byte string of the signature """ return self['signature'].native @property def sha1(self): """ :return: The SHA1 hash of the DER-encoded bytes of this certificate list """ if self._sha1 is None: self._sha1 = hashlib.sha1(self.dump()).digest() return self._sha1 @property def sha256(self): """ :return: The SHA-256 hash of the DER-encoded bytes of this certificate list """ if self._sha256 is None: self._sha256 = hashlib.sha256(self.dump()).digest() return self._sha256