| Current File : //lib64/python3.6/site-packages/cryptography/hazmat/backends/openssl/encode_asn1.py |
# This file is dual licensed under the terms of the Apache License, Version
# 2.0, and the BSD License. See the LICENSE file in the root of this repository
# for complete details.
from __future__ import absolute_import, division, print_function
import calendar
import ipaddress
import six
from cryptography import utils, x509
from cryptography.hazmat.backends.openssl.decode_asn1 import (
_CRL_ENTRY_REASON_ENUM_TO_CODE,
_DISTPOINT_TYPE_FULLNAME,
_DISTPOINT_TYPE_RELATIVENAME,
)
from cryptography.x509.name import _ASN1Type
from cryptography.x509.oid import (
CRLEntryExtensionOID,
ExtensionOID,
OCSPExtensionOID,
)
def _encode_asn1_int(backend, x):
"""
Converts a python integer to an ASN1_INTEGER. The returned ASN1_INTEGER
will not be garbage collected (to support adding them to structs that take
ownership of the object). Be sure to register it for GC if it will be
discarded after use.
"""
# Convert Python integer to OpenSSL "bignum" in case value exceeds
# machine's native integer limits (note: `int_to_bn` doesn't automatically
# GC).
i = backend._int_to_bn(x)
i = backend._ffi.gc(i, backend._lib.BN_free)
# Wrap in an ASN.1 integer. Don't GC -- as documented.
i = backend._lib.BN_to_ASN1_INTEGER(i, backend._ffi.NULL)
backend.openssl_assert(i != backend._ffi.NULL)
return i
def _encode_asn1_int_gc(backend, x):
i = _encode_asn1_int(backend, x)
i = backend._ffi.gc(i, backend._lib.ASN1_INTEGER_free)
return i
def _encode_asn1_str(backend, data):
"""
Create an ASN1_OCTET_STRING from a Python byte string.
"""
s = backend._lib.ASN1_OCTET_STRING_new()
res = backend._lib.ASN1_OCTET_STRING_set(s, data, len(data))
backend.openssl_assert(res == 1)
return s
def _encode_asn1_utf8_str(backend, string):
"""
Create an ASN1_UTF8STRING from a Python unicode string.
This object will be an ASN1_STRING with UTF8 type in OpenSSL and
can be decoded with ASN1_STRING_to_UTF8.
"""
s = backend._lib.ASN1_UTF8STRING_new()
res = backend._lib.ASN1_STRING_set(
s, string.encode("utf8"), len(string.encode("utf8"))
)
backend.openssl_assert(res == 1)
return s
def _encode_asn1_str_gc(backend, data):
s = _encode_asn1_str(backend, data)
s = backend._ffi.gc(s, backend._lib.ASN1_OCTET_STRING_free)
return s
def _encode_inhibit_any_policy(backend, inhibit_any_policy):
return _encode_asn1_int_gc(backend, inhibit_any_policy.skip_certs)
def _encode_name(backend, name):
"""
The X509_NAME created will not be gc'd. Use _encode_name_gc if needed.
"""
subject = backend._lib.X509_NAME_new()
for rdn in name.rdns:
set_flag = 0 # indicate whether to add to last RDN or create new RDN
for attribute in rdn:
name_entry = _encode_name_entry(backend, attribute)
# X509_NAME_add_entry dups the object so we need to gc this copy
name_entry = backend._ffi.gc(
name_entry, backend._lib.X509_NAME_ENTRY_free
)
res = backend._lib.X509_NAME_add_entry(
subject, name_entry, -1, set_flag
)
backend.openssl_assert(res == 1)
set_flag = -1
return subject
def _encode_name_gc(backend, attributes):
subject = _encode_name(backend, attributes)
subject = backend._ffi.gc(subject, backend._lib.X509_NAME_free)
return subject
def _encode_sk_name_entry(backend, attributes):
"""
The sk_X509_NAME_ENTRY created will not be gc'd.
"""
stack = backend._lib.sk_X509_NAME_ENTRY_new_null()
for attribute in attributes:
name_entry = _encode_name_entry(backend, attribute)
res = backend._lib.sk_X509_NAME_ENTRY_push(stack, name_entry)
backend.openssl_assert(res >= 1)
return stack
def _encode_name_entry(backend, attribute):
if attribute._type is _ASN1Type.BMPString:
value = attribute.value.encode("utf_16_be")
elif attribute._type is _ASN1Type.UniversalString:
value = attribute.value.encode("utf_32_be")
else:
value = attribute.value.encode("utf8")
obj = _txt2obj_gc(backend, attribute.oid.dotted_string)
name_entry = backend._lib.X509_NAME_ENTRY_create_by_OBJ(
backend._ffi.NULL, obj, attribute._type.value, value, len(value)
)
return name_entry
def _encode_crl_number_delta_crl_indicator(backend, ext):
return _encode_asn1_int_gc(backend, ext.crl_number)
def _encode_issuing_dist_point(backend, ext):
idp = backend._lib.ISSUING_DIST_POINT_new()
backend.openssl_assert(idp != backend._ffi.NULL)
idp = backend._ffi.gc(idp, backend._lib.ISSUING_DIST_POINT_free)
idp.onlyuser = 255 if ext.only_contains_user_certs else 0
idp.onlyCA = 255 if ext.only_contains_ca_certs else 0
idp.indirectCRL = 255 if ext.indirect_crl else 0
idp.onlyattr = 255 if ext.only_contains_attribute_certs else 0
if ext.only_some_reasons:
idp.onlysomereasons = _encode_reasonflags(
backend, ext.only_some_reasons
)
if ext.full_name:
idp.distpoint = _encode_full_name(backend, ext.full_name)
if ext.relative_name:
idp.distpoint = _encode_relative_name(backend, ext.relative_name)
return idp
def _encode_crl_reason(backend, crl_reason):
asn1enum = backend._lib.ASN1_ENUMERATED_new()
backend.openssl_assert(asn1enum != backend._ffi.NULL)
asn1enum = backend._ffi.gc(asn1enum, backend._lib.ASN1_ENUMERATED_free)
res = backend._lib.ASN1_ENUMERATED_set(
asn1enum, _CRL_ENTRY_REASON_ENUM_TO_CODE[crl_reason.reason]
)
backend.openssl_assert(res == 1)
return asn1enum
def _encode_invalidity_date(backend, invalidity_date):
time = backend._lib.ASN1_GENERALIZEDTIME_set(
backend._ffi.NULL,
calendar.timegm(invalidity_date.invalidity_date.timetuple()),
)
backend.openssl_assert(time != backend._ffi.NULL)
time = backend._ffi.gc(time, backend._lib.ASN1_GENERALIZEDTIME_free)
return time
def _encode_certificate_policies(backend, certificate_policies):
cp = backend._lib.sk_POLICYINFO_new_null()
backend.openssl_assert(cp != backend._ffi.NULL)
cp = backend._ffi.gc(cp, backend._lib.sk_POLICYINFO_free)
for policy_info in certificate_policies:
pi = backend._lib.POLICYINFO_new()
backend.openssl_assert(pi != backend._ffi.NULL)
res = backend._lib.sk_POLICYINFO_push(cp, pi)
backend.openssl_assert(res >= 1)
oid = _txt2obj(backend, policy_info.policy_identifier.dotted_string)
pi.policyid = oid
if policy_info.policy_qualifiers:
pqis = backend._lib.sk_POLICYQUALINFO_new_null()
backend.openssl_assert(pqis != backend._ffi.NULL)
for qualifier in policy_info.policy_qualifiers:
pqi = backend._lib.POLICYQUALINFO_new()
backend.openssl_assert(pqi != backend._ffi.NULL)
res = backend._lib.sk_POLICYQUALINFO_push(pqis, pqi)
backend.openssl_assert(res >= 1)
if isinstance(qualifier, six.text_type):
pqi.pqualid = _txt2obj(
backend, x509.OID_CPS_QUALIFIER.dotted_string
)
pqi.d.cpsuri = _encode_asn1_str(
backend,
qualifier.encode("ascii"),
)
else:
assert isinstance(qualifier, x509.UserNotice)
pqi.pqualid = _txt2obj(
backend, x509.OID_CPS_USER_NOTICE.dotted_string
)
un = backend._lib.USERNOTICE_new()
backend.openssl_assert(un != backend._ffi.NULL)
pqi.d.usernotice = un
if qualifier.explicit_text:
un.exptext = _encode_asn1_utf8_str(
backend, qualifier.explicit_text
)
un.noticeref = _encode_notice_reference(
backend, qualifier.notice_reference
)
pi.qualifiers = pqis
return cp
def _encode_notice_reference(backend, notice):
if notice is None:
return backend._ffi.NULL
else:
nr = backend._lib.NOTICEREF_new()
backend.openssl_assert(nr != backend._ffi.NULL)
# organization is a required field
nr.organization = _encode_asn1_utf8_str(backend, notice.organization)
notice_stack = backend._lib.sk_ASN1_INTEGER_new_null()
nr.noticenos = notice_stack
for number in notice.notice_numbers:
num = _encode_asn1_int(backend, number)
res = backend._lib.sk_ASN1_INTEGER_push(notice_stack, num)
backend.openssl_assert(res >= 1)
return nr
def _txt2obj(backend, name):
"""
Converts a Python string with an ASN.1 object ID in dotted form to a
ASN1_OBJECT.
"""
name = name.encode("ascii")
obj = backend._lib.OBJ_txt2obj(name, 1)
backend.openssl_assert(obj != backend._ffi.NULL)
return obj
def _txt2obj_gc(backend, name):
obj = _txt2obj(backend, name)
obj = backend._ffi.gc(obj, backend._lib.ASN1_OBJECT_free)
return obj
def _encode_ocsp_nocheck(backend, ext):
# Doesn't need to be GC'd
return backend._lib.ASN1_NULL_new()
def _encode_key_usage(backend, key_usage):
set_bit = backend._lib.ASN1_BIT_STRING_set_bit
ku = backend._lib.ASN1_BIT_STRING_new()
ku = backend._ffi.gc(ku, backend._lib.ASN1_BIT_STRING_free)
res = set_bit(ku, 0, key_usage.digital_signature)
backend.openssl_assert(res == 1)
res = set_bit(ku, 1, key_usage.content_commitment)
backend.openssl_assert(res == 1)
res = set_bit(ku, 2, key_usage.key_encipherment)
backend.openssl_assert(res == 1)
res = set_bit(ku, 3, key_usage.data_encipherment)
backend.openssl_assert(res == 1)
res = set_bit(ku, 4, key_usage.key_agreement)
backend.openssl_assert(res == 1)
res = set_bit(ku, 5, key_usage.key_cert_sign)
backend.openssl_assert(res == 1)
res = set_bit(ku, 6, key_usage.crl_sign)
backend.openssl_assert(res == 1)
if key_usage.key_agreement:
res = set_bit(ku, 7, key_usage.encipher_only)
backend.openssl_assert(res == 1)
res = set_bit(ku, 8, key_usage.decipher_only)
backend.openssl_assert(res == 1)
else:
res = set_bit(ku, 7, 0)
backend.openssl_assert(res == 1)
res = set_bit(ku, 8, 0)
backend.openssl_assert(res == 1)
return ku
def _encode_authority_key_identifier(backend, authority_keyid):
akid = backend._lib.AUTHORITY_KEYID_new()
backend.openssl_assert(akid != backend._ffi.NULL)
akid = backend._ffi.gc(akid, backend._lib.AUTHORITY_KEYID_free)
if authority_keyid.key_identifier is not None:
akid.keyid = _encode_asn1_str(
backend,
authority_keyid.key_identifier,
)
if authority_keyid.authority_cert_issuer is not None:
akid.issuer = _encode_general_names(
backend, authority_keyid.authority_cert_issuer
)
if authority_keyid.authority_cert_serial_number is not None:
akid.serial = _encode_asn1_int(
backend, authority_keyid.authority_cert_serial_number
)
return akid
def _encode_basic_constraints(backend, basic_constraints):
constraints = backend._lib.BASIC_CONSTRAINTS_new()
constraints = backend._ffi.gc(
constraints, backend._lib.BASIC_CONSTRAINTS_free
)
constraints.ca = 255 if basic_constraints.ca else 0
if basic_constraints.ca and basic_constraints.path_length is not None:
constraints.pathlen = _encode_asn1_int(
backend, basic_constraints.path_length
)
return constraints
def _encode_information_access(backend, info_access):
aia = backend._lib.sk_ACCESS_DESCRIPTION_new_null()
backend.openssl_assert(aia != backend._ffi.NULL)
aia = backend._ffi.gc(
aia,
lambda x: backend._lib.sk_ACCESS_DESCRIPTION_pop_free(
x,
backend._ffi.addressof(
backend._lib._original_lib, "ACCESS_DESCRIPTION_free"
),
),
)
for access_description in info_access:
ad = backend._lib.ACCESS_DESCRIPTION_new()
method = _txt2obj(
backend, access_description.access_method.dotted_string
)
_encode_general_name_preallocated(
backend, access_description.access_location, ad.location
)
ad.method = method
res = backend._lib.sk_ACCESS_DESCRIPTION_push(aia, ad)
backend.openssl_assert(res >= 1)
return aia
def _encode_general_names(backend, names):
general_names = backend._lib.GENERAL_NAMES_new()
backend.openssl_assert(general_names != backend._ffi.NULL)
for name in names:
gn = _encode_general_name(backend, name)
res = backend._lib.sk_GENERAL_NAME_push(general_names, gn)
backend.openssl_assert(res != 0)
return general_names
def _encode_alt_name(backend, san):
general_names = _encode_general_names(backend, san)
general_names = backend._ffi.gc(
general_names, backend._lib.GENERAL_NAMES_free
)
return general_names
def _encode_subject_key_identifier(backend, ski):
return _encode_asn1_str_gc(backend, ski.digest)
def _encode_general_name(backend, name):
gn = backend._lib.GENERAL_NAME_new()
_encode_general_name_preallocated(backend, name, gn)
return gn
def _encode_general_name_preallocated(backend, name, gn):
if isinstance(name, x509.DNSName):
backend.openssl_assert(gn != backend._ffi.NULL)
gn.type = backend._lib.GEN_DNS
ia5 = backend._lib.ASN1_IA5STRING_new()
backend.openssl_assert(ia5 != backend._ffi.NULL)
# ia5strings are supposed to be ITU T.50 but to allow round-tripping
# of broken certs that encode utf8 we'll encode utf8 here too.
value = name.value.encode("utf8")
res = backend._lib.ASN1_STRING_set(ia5, value, len(value))
backend.openssl_assert(res == 1)
gn.d.dNSName = ia5
elif isinstance(name, x509.RegisteredID):
backend.openssl_assert(gn != backend._ffi.NULL)
gn.type = backend._lib.GEN_RID
obj = backend._lib.OBJ_txt2obj(
name.value.dotted_string.encode("ascii"), 1
)
backend.openssl_assert(obj != backend._ffi.NULL)
gn.d.registeredID = obj
elif isinstance(name, x509.DirectoryName):
backend.openssl_assert(gn != backend._ffi.NULL)
dir_name = _encode_name(backend, name.value)
gn.type = backend._lib.GEN_DIRNAME
gn.d.directoryName = dir_name
elif isinstance(name, x509.IPAddress):
backend.openssl_assert(gn != backend._ffi.NULL)
if isinstance(name.value, ipaddress.IPv4Network):
packed = name.value.network_address.packed + utils.int_to_bytes(
((1 << 32) - name.value.num_addresses), 4
)
elif isinstance(name.value, ipaddress.IPv6Network):
packed = name.value.network_address.packed + utils.int_to_bytes(
(1 << 128) - name.value.num_addresses, 16
)
else:
packed = name.value.packed
ipaddr = _encode_asn1_str(backend, packed)
gn.type = backend._lib.GEN_IPADD
gn.d.iPAddress = ipaddr
elif isinstance(name, x509.OtherName):
backend.openssl_assert(gn != backend._ffi.NULL)
other_name = backend._lib.OTHERNAME_new()
backend.openssl_assert(other_name != backend._ffi.NULL)
type_id = backend._lib.OBJ_txt2obj(
name.type_id.dotted_string.encode("ascii"), 1
)
backend.openssl_assert(type_id != backend._ffi.NULL)
data = backend._ffi.new("unsigned char[]", name.value)
data_ptr_ptr = backend._ffi.new("unsigned char **")
data_ptr_ptr[0] = data
value = backend._lib.d2i_ASN1_TYPE(
backend._ffi.NULL, data_ptr_ptr, len(name.value)
)
if value == backend._ffi.NULL:
backend._consume_errors()
raise ValueError("Invalid ASN.1 data")
other_name.type_id = type_id
other_name.value = value
gn.type = backend._lib.GEN_OTHERNAME
gn.d.otherName = other_name
elif isinstance(name, x509.RFC822Name):
backend.openssl_assert(gn != backend._ffi.NULL)
# ia5strings are supposed to be ITU T.50 but to allow round-tripping
# of broken certs that encode utf8 we'll encode utf8 here too.
data = name.value.encode("utf8")
asn1_str = _encode_asn1_str(backend, data)
gn.type = backend._lib.GEN_EMAIL
gn.d.rfc822Name = asn1_str
elif isinstance(name, x509.UniformResourceIdentifier):
backend.openssl_assert(gn != backend._ffi.NULL)
# ia5strings are supposed to be ITU T.50 but to allow round-tripping
# of broken certs that encode utf8 we'll encode utf8 here too.
data = name.value.encode("utf8")
asn1_str = _encode_asn1_str(backend, data)
gn.type = backend._lib.GEN_URI
gn.d.uniformResourceIdentifier = asn1_str
else:
raise ValueError("{} is an unknown GeneralName type".format(name))
def _encode_extended_key_usage(backend, extended_key_usage):
eku = backend._lib.sk_ASN1_OBJECT_new_null()
eku = backend._ffi.gc(eku, backend._lib.sk_ASN1_OBJECT_free)
for oid in extended_key_usage:
obj = _txt2obj(backend, oid.dotted_string)
res = backend._lib.sk_ASN1_OBJECT_push(eku, obj)
backend.openssl_assert(res >= 1)
return eku
_CRLREASONFLAGS = {
x509.ReasonFlags.key_compromise: 1,
x509.ReasonFlags.ca_compromise: 2,
x509.ReasonFlags.affiliation_changed: 3,
x509.ReasonFlags.superseded: 4,
x509.ReasonFlags.cessation_of_operation: 5,
x509.ReasonFlags.certificate_hold: 6,
x509.ReasonFlags.privilege_withdrawn: 7,
x509.ReasonFlags.aa_compromise: 8,
}
def _encode_reasonflags(backend, reasons):
bitmask = backend._lib.ASN1_BIT_STRING_new()
backend.openssl_assert(bitmask != backend._ffi.NULL)
for reason in reasons:
res = backend._lib.ASN1_BIT_STRING_set_bit(
bitmask, _CRLREASONFLAGS[reason], 1
)
backend.openssl_assert(res == 1)
return bitmask
def _encode_full_name(backend, full_name):
dpn = backend._lib.DIST_POINT_NAME_new()
backend.openssl_assert(dpn != backend._ffi.NULL)
dpn.type = _DISTPOINT_TYPE_FULLNAME
dpn.name.fullname = _encode_general_names(backend, full_name)
return dpn
def _encode_relative_name(backend, relative_name):
dpn = backend._lib.DIST_POINT_NAME_new()
backend.openssl_assert(dpn != backend._ffi.NULL)
dpn.type = _DISTPOINT_TYPE_RELATIVENAME
dpn.name.relativename = _encode_sk_name_entry(backend, relative_name)
return dpn
def _encode_cdps_freshest_crl(backend, cdps):
cdp = backend._lib.sk_DIST_POINT_new_null()
cdp = backend._ffi.gc(cdp, backend._lib.sk_DIST_POINT_free)
for point in cdps:
dp = backend._lib.DIST_POINT_new()
backend.openssl_assert(dp != backend._ffi.NULL)
if point.reasons:
dp.reasons = _encode_reasonflags(backend, point.reasons)
if point.full_name:
dp.distpoint = _encode_full_name(backend, point.full_name)
if point.relative_name:
dp.distpoint = _encode_relative_name(backend, point.relative_name)
if point.crl_issuer:
dp.CRLissuer = _encode_general_names(backend, point.crl_issuer)
res = backend._lib.sk_DIST_POINT_push(cdp, dp)
backend.openssl_assert(res >= 1)
return cdp
def _encode_name_constraints(backend, name_constraints):
nc = backend._lib.NAME_CONSTRAINTS_new()
backend.openssl_assert(nc != backend._ffi.NULL)
nc = backend._ffi.gc(nc, backend._lib.NAME_CONSTRAINTS_free)
permitted = _encode_general_subtree(
backend, name_constraints.permitted_subtrees
)
nc.permittedSubtrees = permitted
excluded = _encode_general_subtree(
backend, name_constraints.excluded_subtrees
)
nc.excludedSubtrees = excluded
return nc
def _encode_policy_constraints(backend, policy_constraints):
pc = backend._lib.POLICY_CONSTRAINTS_new()
backend.openssl_assert(pc != backend._ffi.NULL)
pc = backend._ffi.gc(pc, backend._lib.POLICY_CONSTRAINTS_free)
if policy_constraints.require_explicit_policy is not None:
pc.requireExplicitPolicy = _encode_asn1_int(
backend, policy_constraints.require_explicit_policy
)
if policy_constraints.inhibit_policy_mapping is not None:
pc.inhibitPolicyMapping = _encode_asn1_int(
backend, policy_constraints.inhibit_policy_mapping
)
return pc
def _encode_general_subtree(backend, subtrees):
if subtrees is None:
return backend._ffi.NULL
else:
general_subtrees = backend._lib.sk_GENERAL_SUBTREE_new_null()
for name in subtrees:
gs = backend._lib.GENERAL_SUBTREE_new()
gs.base = _encode_general_name(backend, name)
res = backend._lib.sk_GENERAL_SUBTREE_push(general_subtrees, gs)
assert res >= 1
return general_subtrees
def _encode_nonce(backend, nonce):
return _encode_asn1_str_gc(backend, nonce.nonce)
_EXTENSION_ENCODE_HANDLERS = {
ExtensionOID.BASIC_CONSTRAINTS: _encode_basic_constraints,
ExtensionOID.SUBJECT_KEY_IDENTIFIER: _encode_subject_key_identifier,
ExtensionOID.KEY_USAGE: _encode_key_usage,
ExtensionOID.SUBJECT_ALTERNATIVE_NAME: _encode_alt_name,
ExtensionOID.ISSUER_ALTERNATIVE_NAME: _encode_alt_name,
ExtensionOID.EXTENDED_KEY_USAGE: _encode_extended_key_usage,
ExtensionOID.AUTHORITY_KEY_IDENTIFIER: _encode_authority_key_identifier,
ExtensionOID.CERTIFICATE_POLICIES: _encode_certificate_policies,
ExtensionOID.AUTHORITY_INFORMATION_ACCESS: _encode_information_access,
ExtensionOID.SUBJECT_INFORMATION_ACCESS: _encode_information_access,
ExtensionOID.CRL_DISTRIBUTION_POINTS: _encode_cdps_freshest_crl,
ExtensionOID.FRESHEST_CRL: _encode_cdps_freshest_crl,
ExtensionOID.INHIBIT_ANY_POLICY: _encode_inhibit_any_policy,
ExtensionOID.OCSP_NO_CHECK: _encode_ocsp_nocheck,
ExtensionOID.NAME_CONSTRAINTS: _encode_name_constraints,
ExtensionOID.POLICY_CONSTRAINTS: _encode_policy_constraints,
}
_CRL_EXTENSION_ENCODE_HANDLERS = {
ExtensionOID.ISSUER_ALTERNATIVE_NAME: _encode_alt_name,
ExtensionOID.AUTHORITY_KEY_IDENTIFIER: _encode_authority_key_identifier,
ExtensionOID.AUTHORITY_INFORMATION_ACCESS: _encode_information_access,
ExtensionOID.CRL_NUMBER: _encode_crl_number_delta_crl_indicator,
ExtensionOID.DELTA_CRL_INDICATOR: _encode_crl_number_delta_crl_indicator,
ExtensionOID.ISSUING_DISTRIBUTION_POINT: _encode_issuing_dist_point,
ExtensionOID.FRESHEST_CRL: _encode_cdps_freshest_crl,
}
_CRL_ENTRY_EXTENSION_ENCODE_HANDLERS = {
CRLEntryExtensionOID.CERTIFICATE_ISSUER: _encode_alt_name,
CRLEntryExtensionOID.CRL_REASON: _encode_crl_reason,
CRLEntryExtensionOID.INVALIDITY_DATE: _encode_invalidity_date,
}
_OCSP_REQUEST_EXTENSION_ENCODE_HANDLERS = {
OCSPExtensionOID.NONCE: _encode_nonce,
}
_OCSP_BASICRESP_EXTENSION_ENCODE_HANDLERS = {
OCSPExtensionOID.NONCE: _encode_nonce,
}