# coding: utf-8
"""
ASN.1 type classes for the online certificate status protocol (OCSP). Exports
the following items:
- OCSPRequest()
- OCSPResponse()
Other type classes are defined that help compose the types listed above.
"""
from __future__ import unicode_literals, division, absolute_import, print_function
from .algos import DigestAlgorithm, SignedDigestAlgorithm
from .core import (
Boolean,
Choice,
Enumerated,
GeneralizedTime,
IA5String,
Integer,
Null,
ObjectIdentifier,
OctetBitString,
OctetString,
ParsableOctetString,
Sequence,
SequenceOf,
)
from .crl import AuthorityInfoAccessSyntax, CRLReason
from .keys import PublicKeyAlgorithm
from .x509 import Certificate, GeneralName, GeneralNames, Name
# The structures in this file are taken from https://tools.ietf.org/html/rfc6960
class Version(Integer):
_map = {
0: 'v1'
}
class CertId(Sequence):
_fields = [
('hash_algorithm', DigestAlgorithm),
('issuer_name_hash', OctetString),
('issuer_key_hash', OctetString),
('serial_number', Integer),
]
class ServiceLocator(Sequence):
_fields = [
('issuer', Name),
('locator', AuthorityInfoAccessSyntax),
]
class RequestExtensionId(ObjectIdentifier):
_map = {
'1.3.6.1.5.5.7.48.1.7': 'service_locator',
}
class RequestExtension(Sequence):
_fields = [
('extn_id', RequestExtensionId),
('critical', Boolean, {'default': False}),
('extn_value', ParsableOctetString),
]
_oid_pair = ('extn_id', 'extn_value')
_oid_specs = {
'service_locator': ServiceLocator,
}
class RequestExtensions(SequenceOf):
_child_spec = RequestExtension
class Request(Sequence):
_fields = [
('req_cert', CertId),
('single_request_extensions', RequestExtensions, {'tag_type': 'explicit', 'tag': 0, 'optional': True}),
]
_processed_extensions = False
_critical_extensions = None
_service_locator_value = 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['single_request_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 service_locator_value(self):
"""
This extension is used when communicating with an OCSP responder that
acts as a proxy for OCSP requests
:return:
None or a ServiceLocator object
"""
if self._processed_extensions is False:
self._set_extensions()
return self._service_locator_value
class Requests(SequenceOf):
_child_spec = Request
class ResponseType(ObjectIdentifier):
_map = {
'1.3.6.1.5.5.7.48.1.1': 'basic_ocsp_response',
}
class AcceptableResponses(SequenceOf):
_child_spec = ResponseType
class PreferredSignatureAlgorithm(Sequence):
_fields = [
('sig_identifier', SignedDigestAlgorithm),
('cert_identifier', PublicKeyAlgorithm, {'optional': True}),
]
class PreferredSignatureAlgorithms(SequenceOf):
_child_spec = PreferredSignatureAlgorithm
class TBSRequestExtensionId(ObjectIdentifier):
_map = {
'1.3.6.1.5.5.7.48.1.2': 'nonce',
'1.3.6.1.5.5.7.48.1.4': 'acceptable_responses',
'1.3.6.1.5.5.7.48.1.8': 'preferred_signature_algorithms',
}
class TBSRequestExtension(Sequence):
_fields = [
('extn_id', TBSRequestExtensionId),
('critical', Boolean, {'default': False}),
('extn_value', ParsableOctetString),
]
_oid_pair = ('extn_id', 'extn_value')
_oid_specs = {
'nonce': OctetString,
'acceptable_responses': AcceptableResponses,
'preferred_signature_algorithms': PreferredSignatureAlgorithms,
}
class TBSRequestExtensions(SequenceOf):
_child_spec = TBSRequestExtension
class TBSRequest(Sequence):
_fields = [
('version', Version, {'tag_type': 'explicit', 'tag': 0, 'default': 'v1'}),
('requestor_name', GeneralName, {'tag_type': 'explicit', 'tag': 1, 'optional': True}),
('request_list', Requests),
('request_extensions', TBSRequestExtensions, {'tag_type': 'explicit', 'tag': 2, 'optional': True}),
]
class Certificates(SequenceOf):
_child_spec = Certificate
class Signature(Sequence):
_fields = [
('signature_algorithm', SignedDigestAlgorithm),
('signature', OctetBitString),
('certs', Certificates, {'tag_type': 'explicit', 'tag': 0, 'optional': True}),
]
class OCSPRequest(Sequence):
_fields = [
('tbs_request', TBSRequest),
('optional_signature', Signature, {'tag_type': 'explicit', 'tag': 0, 'optional': True}),
]
_processed_extensions = False
_critical_extensions = None
_nonce_value = None
_acceptable_responses_value = None
_preferred_signature_algorithms_value = 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_request']['request_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 nonce_value(self):
"""
This extension is used to prevent replay attacks by including a unique,
random value with each request/response pair
:return:
None or an OctetString object
"""
if self._processed_extensions is False:
self._set_extensions()
return self._nonce_value
@property
def acceptable_responses_value(self):
"""
This extension is used to allow the client and server to communicate
with alternative response formats other than just basic_ocsp_response,
although no other formats are defined in the standard.
:return:
None or an AcceptableResponses object
"""
if self._processed_extensions is False:
self._set_extensions()
return self._acceptable_responses_value
@property
def preferred_signature_algorithms_value(self):
"""
This extension is used by the client to define what signature algorithms
are preferred, including both the hash algorithm and the public key
algorithm, with a level of detail down to even the public key algorithm
parameters, such as curve name.
:return:
None or a PreferredSignatureAlgorithms object
"""
if self._processed_extensions is False:
self._set_extensions()
return self._preferred_signature_algorithms_value
class OCSPResponseStatus(Enumerated):
_map = {
0: 'successful',
1: 'malformed_request',
2: 'internal_error',
3: 'try_later',
5: 'sign_required',
6: 'unauthorized',
}
class ResponderId(Choice):
_alternatives = [
('by_name', Name, {'tag_type': 'explicit', 'tag': 1}),
('by_key', OctetString, {'tag_type': 'explicit', 'tag': 2}),
]
class RevokedInfo(Sequence):
_fields = [
('revocation_time', GeneralizedTime),
('revocation_reason', CRLReason, {'tag_type': 'explicit', 'tag': 0, 'optional': True}),
]
class CertStatus(Choice):
_alternatives = [
('good', Null, {'tag_type': 'implicit', 'tag': 0}),
('revoked', RevokedInfo, {'tag_type': 'implicit', 'tag': 1}),
('unknown', Null, {'tag_type': 'implicit', 'tag': 2}),
]
class CrlId(Sequence):
_fields = [
('crl_url', IA5String, {'tag_type': 'explicit', 'tag': 0, 'optional': True}),
('crl_num', Integer, {'tag_type': 'explicit', 'tag': 1, 'optional': True}),
('crl_time', GeneralizedTime, {'tag_type': 'explicit', 'tag': 2, 'optional': True}),
]
class SingleResponseExtensionId(ObjectIdentifier):
_map = {
'1.3.6.1.5.5.7.48.1.3': 'crl',
'1.3.6.1.5.5.7.48.1.6': 'archive_cutoff',
# These are CRLEntryExtension values from
# https://tools.ietf.org/html/rfc5280
'2.5.29.21': 'crl_reason',
'2.5.29.24': 'invalidity_date',
'2.5.29.29': 'certificate_issuer',
}
class SingleResponseExtension(Sequence):
_fields = [
('extn_id', SingleResponseExtensionId),
('critical', Boolean, {'default': False}),
('extn_value', ParsableOctetString),
]
_oid_pair = ('extn_id', 'extn_value')
_oid_specs = {
'crl': CrlId,
'archive_cutoff': GeneralizedTime,
'crl_reason': CRLReason,
'invalidity_date': GeneralizedTime,
'certificate_issuer': GeneralNames,
}
class SingleResponseExtensions(SequenceOf):
_child_spec = SingleResponseExtension
class SingleResponse(Sequence):
_fields = [
('cert_id', CertId),
('cert_status', CertStatus),
('this_update', GeneralizedTime),
('next_update', GeneralizedTime, {'tag_type': 'explicit', 'tag': 0, 'optional': True}),
('single_extensions', SingleResponseExtensions, {'tag_type': 'explicit', 'tag': 1, 'optional': True}),
]
_processed_extensions = False
_critical_extensions = None
_crl_value = None
_archive_cutoff_value = None
_crl_reason_value = None
_invalidity_date_value = None
_certificate_issuer_value = 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['single_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_value(self):
"""
This extension is used to locate the CRL that a certificate's revocation
is contained within.
:return:
None or a CrlId object
"""
if self._processed_extensions is False:
self._set_extensions()
return self._crl_value
@property
def archive_cutoff_value(self):
"""
This extension is used to indicate the date at which an archived
(historical) certificate status entry will no longer be available.
:return:
None or a GeneralizedTime object
"""
if self._processed_extensions is False:
self._set_extensions()
return self._archive_cutoff_value
@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.
:return:
None or an x509.GeneralNames object
"""
if self._processed_extensions is False:
self._set_extensions()
return self._certificate_issuer_value
class Responses(SequenceOf):
_child_spec = SingleResponse
class ResponseDataExtensionId(ObjectIdentifier):
_map = {
'1.3.6.1.5.5.7.48.1.2': 'nonce',
'1.3.6.1.5.5.7.48.1.9': 'extended_revoke',
}
class ResponseDataExtension(Sequence):
_fields = [
('extn_id', ResponseDataExtensionId),
('critical', Boolean, {'default': False}),
('extn_value', ParsableOctetString),
]
_oid_pair = ('extn_id', 'extn_value')
_oid_specs = {
'nonce': OctetString,
'extended_revoke': Null,
}
class ResponseDataExtensions(SequenceOf):
_child_spec = ResponseDataExtension
class ResponseData(Sequence):
_fields = [
('version', Version, {'tag_type': 'explicit', 'tag': 0, 'default': 'v1'}),
('responder_id', ResponderId),
('produced_at', GeneralizedTime),
('responses', Responses),
('response_extensions', ResponseDataExtensions, {'tag_type': 'explicit', 'tag': 1, 'optional': True}),
]
class BasicOCSPResponse(Sequence):
_fields = [
('tbs_response_data', ResponseData),
('signature_algorithm', SignedDigestAlgorithm),
('signature', OctetBitString),
('certs', Certificates, {'tag_type': 'explicit', 'tag': 0, 'optional': True}),
]
class ResponseBytes(Sequence):
_fields = [
('response_type', ResponseType),
('response', ParsableOctetString),
]
_oid_pair = ('response_type', 'response')
_oid_specs = {
'basic_ocsp_response': BasicOCSPResponse,
}
class OCSPResponse(Sequence):
_fields = [
('response_status', OCSPResponseStatus),
('response_bytes', ResponseBytes, {'tag_type': 'explicit', 'tag': 0, 'optional': True}),
]
_processed_extensions = False
_critical_extensions = None
_nonce_value = None
_extended_revoke_value = 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['response_bytes']['response'].parsed['tbs_response_data']['response_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 nonce_value(self):
"""
This extension is used to prevent replay attacks on the request/response
exchange
:return:
None or an OctetString object
"""
if self._processed_extensions is False:
self._set_extensions()
return self._nonce_value
@property
def extended_revoke_value(self):
"""
This extension is used to signal that the responder will return a
"revoked" status for non-issued certificates.
:return:
None or a Null object (if present)
"""
if self._processed_extensions is False:
self._set_extensions()
return self._extended_revoke_value
@property
def basic_ocsp_response(self):
"""
A shortcut into the BasicOCSPResponse sequence
:return:
None or an asn1crypto.ocsp.BasicOCSPResponse object
"""
return self['response_bytes']['response'].parsed
@property
def response_data(self):
"""
A shortcut into the parsed, ResponseData sequence
:return:
None or an asn1crypto.ocsp.ResponseData object
"""
return self['response_bytes']['response'].parsed['tbs_response_data']
