def _build_x509_name(self, x509_name):
count = self._backend._lib.X509_NAME_entry_count(x509_name)
attributes = []
for x in range(count):
entry = self._backend._lib.X509_NAME_get_entry(x509_name, x)
obj = self._backend._lib.X509_NAME_ENTRY_get_object(entry)
assert obj != self._backend._ffi.NULL
data = self._backend._lib.X509_NAME_ENTRY_get_data(entry)
assert data != self._backend._ffi.NULL
buf = self._backend._ffi.new("unsigned char **")
res = self._backend._lib.ASN1_STRING_to_UTF8(buf, data)
assert res >= 0
assert buf[0] != self._backend._ffi.NULL
buf = self._backend._ffi.gc(
buf, lambda buf: self._backend._lib.OPENSSL_free(buf[0])
)
value = self._backend._ffi.buffer(buf[0], res)[:].decode('utf8')
oid = self._obj2txt(obj)
attributes.append(
x509.NameAttribute(
x509.ObjectIdentifier(oid), value
)
)
return x509.Name(attributes)
python类ObjectIdentifier()的实例源码
def _build_x509_name(self, x509_name):
count = self._backend._lib.X509_NAME_entry_count(x509_name)
attributes = []
for x in range(count):
entry = self._backend._lib.X509_NAME_get_entry(x509_name, x)
obj = self._backend._lib.X509_NAME_ENTRY_get_object(entry)
assert obj != self._backend._ffi.NULL
data = self._backend._lib.X509_NAME_ENTRY_get_data(entry)
assert data != self._backend._ffi.NULL
buf = self._backend._ffi.new("unsigned char **")
res = self._backend._lib.ASN1_STRING_to_UTF8(buf, data)
assert res >= 0
assert buf[0] != self._backend._ffi.NULL
buf = self._backend._ffi.gc(
buf, lambda buf: self._backend._lib.OPENSSL_free(buf[0])
)
value = self._backend._ffi.buffer(buf[0], res)[:].decode('utf8')
oid = self._obj2txt(obj)
attributes.append(
x509.NameAttribute(
x509.ObjectIdentifier(oid), value
)
)
return x509.Name(attributes)
def _build_x509_name(self, x509_name):
count = self._backend._lib.X509_NAME_entry_count(x509_name)
attributes = []
for x in range(count):
entry = self._backend._lib.X509_NAME_get_entry(x509_name, x)
obj = self._backend._lib.X509_NAME_ENTRY_get_object(entry)
assert obj != self._backend._ffi.NULL
data = self._backend._lib.X509_NAME_ENTRY_get_data(entry)
assert data != self._backend._ffi.NULL
buf = self._backend._ffi.new("unsigned char **")
res = self._backend._lib.ASN1_STRING_to_UTF8(buf, data)
assert res >= 0
assert buf[0] != self._backend._ffi.NULL
buf = self._backend._ffi.gc(
buf, lambda buf: self._backend._lib.OPENSSL_free(buf[0])
)
value = self._backend._ffi.buffer(buf[0], res)[:].decode('utf8')
oid = self._obj2txt(obj)
attributes.append(
x509.NameAttribute(
x509.ObjectIdentifier(oid), value
)
)
return x509.Name(attributes)
def _decode_x509_name_entry(backend, x509_name_entry):
obj = backend._lib.X509_NAME_ENTRY_get_object(x509_name_entry)
backend.openssl_assert(obj != backend._ffi.NULL)
data = backend._lib.X509_NAME_ENTRY_get_data(x509_name_entry)
backend.openssl_assert(data != backend._ffi.NULL)
value = _asn1_string_to_utf8(backend, data)
oid = _obj2txt(backend, obj)
return x509.NameAttribute(x509.ObjectIdentifier(oid), value)
def _decode_certificate_policies(backend, cp):
cp = backend._ffi.cast("Cryptography_STACK_OF_POLICYINFO *", cp)
cp = backend._ffi.gc(cp, backend._lib.sk_POLICYINFO_free)
num = backend._lib.sk_POLICYINFO_num(cp)
certificate_policies = []
for i in range(num):
qualifiers = None
pi = backend._lib.sk_POLICYINFO_value(cp, i)
oid = x509.ObjectIdentifier(_obj2txt(backend, pi.policyid))
if pi.qualifiers != backend._ffi.NULL:
qnum = backend._lib.sk_POLICYQUALINFO_num(pi.qualifiers)
qualifiers = []
for j in range(qnum):
pqi = backend._lib.sk_POLICYQUALINFO_value(
pi.qualifiers, j
)
pqualid = x509.ObjectIdentifier(
_obj2txt(backend, pqi.pqualid)
)
if pqualid == CertificatePoliciesOID.CPS_QUALIFIER:
cpsuri = backend._ffi.buffer(
pqi.d.cpsuri.data, pqi.d.cpsuri.length
)[:].decode('ascii')
qualifiers.append(cpsuri)
else:
assert pqualid == CertificatePoliciesOID.CPS_USER_NOTICE
user_notice = _decode_user_notice(
backend, pqi.d.usernotice
)
qualifiers.append(user_notice)
certificate_policies.append(
x509.PolicyInformation(oid, qualifiers)
)
return x509.CertificatePolicies(certificate_policies)
def _decode_authority_information_access(backend, aia):
aia = backend._ffi.cast("Cryptography_STACK_OF_ACCESS_DESCRIPTION *", aia)
aia = backend._ffi.gc(aia, backend._lib.sk_ACCESS_DESCRIPTION_free)
num = backend._lib.sk_ACCESS_DESCRIPTION_num(aia)
access_descriptions = []
for i in range(num):
ad = backend._lib.sk_ACCESS_DESCRIPTION_value(aia, i)
backend.openssl_assert(ad.method != backend._ffi.NULL)
oid = x509.ObjectIdentifier(_obj2txt(backend, ad.method))
backend.openssl_assert(ad.location != backend._ffi.NULL)
gn = _decode_general_name(backend, ad.location)
access_descriptions.append(x509.AccessDescription(oid, gn))
return x509.AuthorityInformationAccess(access_descriptions)
def _decode_extended_key_usage(backend, sk):
sk = backend._ffi.cast("Cryptography_STACK_OF_ASN1_OBJECT *", sk)
sk = backend._ffi.gc(sk, backend._lib.sk_ASN1_OBJECT_free)
num = backend._lib.sk_ASN1_OBJECT_num(sk)
ekus = []
for i in range(num):
obj = backend._lib.sk_ASN1_OBJECT_value(sk, i)
backend.openssl_assert(obj != backend._ffi.NULL)
oid = x509.ObjectIdentifier(_obj2txt(backend, obj))
ekus.append(oid)
return x509.ExtendedKeyUsage(ekus)
def _decode_certificate_policies(backend, cp):
cp = backend._ffi.cast("Cryptography_STACK_OF_POLICYINFO *", cp)
cp = backend._ffi.gc(cp, backend._lib.sk_POLICYINFO_free)
num = backend._lib.sk_POLICYINFO_num(cp)
certificate_policies = []
for i in range(num):
qualifiers = None
pi = backend._lib.sk_POLICYINFO_value(cp, i)
oid = x509.ObjectIdentifier(_obj2txt(backend, pi.policyid))
if pi.qualifiers != backend._ffi.NULL:
qnum = backend._lib.sk_POLICYQUALINFO_num(pi.qualifiers)
qualifiers = []
for j in range(qnum):
pqi = backend._lib.sk_POLICYQUALINFO_value(
pi.qualifiers, j
)
pqualid = x509.ObjectIdentifier(
_obj2txt(backend, pqi.pqualid)
)
if pqualid == CertificatePoliciesOID.CPS_QUALIFIER:
cpsuri = backend._ffi.buffer(
pqi.d.cpsuri.data, pqi.d.cpsuri.length
)[:].decode('ascii')
qualifiers.append(cpsuri)
else:
assert pqualid == CertificatePoliciesOID.CPS_USER_NOTICE
user_notice = _decode_user_notice(
backend, pqi.d.usernotice
)
qualifiers.append(user_notice)
certificate_policies.append(
x509.PolicyInformation(oid, qualifiers)
)
return x509.CertificatePolicies(certificate_policies)
def _decode_authority_information_access(backend, aia):
aia = backend._ffi.cast("Cryptography_STACK_OF_ACCESS_DESCRIPTION *", aia)
aia = backend._ffi.gc(aia, backend._lib.sk_ACCESS_DESCRIPTION_free)
num = backend._lib.sk_ACCESS_DESCRIPTION_num(aia)
access_descriptions = []
for i in range(num):
ad = backend._lib.sk_ACCESS_DESCRIPTION_value(aia, i)
backend.openssl_assert(ad.method != backend._ffi.NULL)
oid = x509.ObjectIdentifier(_obj2txt(backend, ad.method))
backend.openssl_assert(ad.location != backend._ffi.NULL)
gn = _decode_general_name(backend, ad.location)
access_descriptions.append(x509.AccessDescription(oid, gn))
return x509.AuthorityInformationAccess(access_descriptions)
def _decode_extended_key_usage(backend, sk):
sk = backend._ffi.cast("Cryptography_STACK_OF_ASN1_OBJECT *", sk)
sk = backend._ffi.gc(sk, backend._lib.sk_ASN1_OBJECT_free)
num = backend._lib.sk_ASN1_OBJECT_num(sk)
ekus = []
for i in range(num):
obj = backend._lib.sk_ASN1_OBJECT_value(sk, i)
backend.openssl_assert(obj != backend._ffi.NULL)
oid = x509.ObjectIdentifier(_obj2txt(backend, obj))
ekus.append(oid)
return x509.ExtendedKeyUsage(ekus)
def signature_algorithm_oid(self):
alg = self._backend._ffi.new("X509_ALGOR **")
self._backend._lib.X509_get0_signature(
self._backend._ffi.NULL, alg, self._x509
)
self._backend.openssl_assert(alg[0] != self._backend._ffi.NULL)
oid = _obj2txt(self._backend, alg[0].algorithm)
return x509.ObjectIdentifier(oid)
def signature_algorithm_oid(self):
alg = self._backend._ffi.new("X509_ALGOR **")
self._backend._lib.X509_CRL_get0_signature(
self._x509_crl, self._backend._ffi.NULL, alg
)
self._backend.openssl_assert(alg[0] != self._backend._ffi.NULL)
oid = _obj2txt(self._backend, alg[0].algorithm)
return x509.ObjectIdentifier(oid)
def signature_algorithm_oid(self):
alg = self._backend._ffi.new("X509_ALGOR **")
self._backend._lib.X509_REQ_get0_signature(
self._x509_req, self._backend._ffi.NULL, alg
)
self._backend.openssl_assert(alg[0] != self._backend._ffi.NULL)
oid = _obj2txt(self._backend, alg[0].algorithm)
return x509.ObjectIdentifier(oid)
def _decode_x509_name_entry(backend, x509_name_entry):
obj = backend._lib.X509_NAME_ENTRY_get_object(x509_name_entry)
backend.openssl_assert(obj != backend._ffi.NULL)
data = backend._lib.X509_NAME_ENTRY_get_data(x509_name_entry)
backend.openssl_assert(data != backend._ffi.NULL)
value = _asn1_string_to_utf8(backend, data)
oid = _obj2txt(backend, obj)
return x509.NameAttribute(x509.ObjectIdentifier(oid), value)
def _decode_authority_information_access(backend, aia):
aia = backend._ffi.cast("Cryptography_STACK_OF_ACCESS_DESCRIPTION *", aia)
aia = backend._ffi.gc(aia, backend._lib.sk_ACCESS_DESCRIPTION_free)
num = backend._lib.sk_ACCESS_DESCRIPTION_num(aia)
access_descriptions = []
for i in range(num):
ad = backend._lib.sk_ACCESS_DESCRIPTION_value(aia, i)
backend.openssl_assert(ad.method != backend._ffi.NULL)
oid = x509.ObjectIdentifier(_obj2txt(backend, ad.method))
backend.openssl_assert(ad.location != backend._ffi.NULL)
gn = _decode_general_name(backend, ad.location)
access_descriptions.append(x509.AccessDescription(oid, gn))
return x509.AuthorityInformationAccess(access_descriptions)
def _decode_extended_key_usage(backend, sk):
sk = backend._ffi.cast("Cryptography_STACK_OF_ASN1_OBJECT *", sk)
sk = backend._ffi.gc(sk, backend._lib.sk_ASN1_OBJECT_free)
num = backend._lib.sk_ASN1_OBJECT_num(sk)
ekus = []
for i in range(num):
obj = backend._lib.sk_ASN1_OBJECT_value(sk, i)
backend.openssl_assert(obj != backend._ffi.NULL)
oid = x509.ObjectIdentifier(_obj2txt(backend, obj))
ekus.append(oid)
return x509.ExtendedKeyUsage(ekus)
def _decode_x509_name_entry(backend, x509_name_entry):
obj = backend._lib.X509_NAME_ENTRY_get_object(x509_name_entry)
backend.openssl_assert(obj != backend._ffi.NULL)
data = backend._lib.X509_NAME_ENTRY_get_data(x509_name_entry)
backend.openssl_assert(data != backend._ffi.NULL)
value = _asn1_string_to_utf8(backend, data)
oid = _obj2txt(backend, obj)
return x509.NameAttribute(x509.ObjectIdentifier(oid), value)
def _decode_certificate_policies(backend, cp):
cp = backend._ffi.cast("Cryptography_STACK_OF_POLICYINFO *", cp)
cp = backend._ffi.gc(cp, backend._lib.sk_POLICYINFO_free)
num = backend._lib.sk_POLICYINFO_num(cp)
certificate_policies = []
for i in range(num):
qualifiers = None
pi = backend._lib.sk_POLICYINFO_value(cp, i)
oid = x509.ObjectIdentifier(_obj2txt(backend, pi.policyid))
if pi.qualifiers != backend._ffi.NULL:
qnum = backend._lib.sk_POLICYQUALINFO_num(pi.qualifiers)
qualifiers = []
for j in range(qnum):
pqi = backend._lib.sk_POLICYQUALINFO_value(
pi.qualifiers, j
)
pqualid = x509.ObjectIdentifier(
_obj2txt(backend, pqi.pqualid)
)
if pqualid == CertificatePoliciesOID.CPS_QUALIFIER:
cpsuri = backend._ffi.buffer(
pqi.d.cpsuri.data, pqi.d.cpsuri.length
)[:].decode('ascii')
qualifiers.append(cpsuri)
else:
assert pqualid == CertificatePoliciesOID.CPS_USER_NOTICE
user_notice = _decode_user_notice(
backend, pqi.d.usernotice
)
qualifiers.append(user_notice)
certificate_policies.append(
x509.PolicyInformation(oid, qualifiers)
)
return x509.CertificatePolicies(certificate_policies)
def _decode_authority_information_access(backend, aia):
aia = backend._ffi.cast("Cryptography_STACK_OF_ACCESS_DESCRIPTION *", aia)
aia = backend._ffi.gc(aia, backend._lib.sk_ACCESS_DESCRIPTION_free)
num = backend._lib.sk_ACCESS_DESCRIPTION_num(aia)
access_descriptions = []
for i in range(num):
ad = backend._lib.sk_ACCESS_DESCRIPTION_value(aia, i)
backend.openssl_assert(ad.method != backend._ffi.NULL)
oid = x509.ObjectIdentifier(_obj2txt(backend, ad.method))
backend.openssl_assert(ad.location != backend._ffi.NULL)
gn = _decode_general_name(backend, ad.location)
access_descriptions.append(x509.AccessDescription(oid, gn))
return x509.AuthorityInformationAccess(access_descriptions)
def _decode_extended_key_usage(backend, sk):
sk = backend._ffi.cast("Cryptography_STACK_OF_ASN1_OBJECT *", sk)
sk = backend._ffi.gc(sk, backend._lib.sk_ASN1_OBJECT_free)
num = backend._lib.sk_ASN1_OBJECT_num(sk)
ekus = []
for i in range(num):
obj = backend._lib.sk_ASN1_OBJECT_value(sk, i)
backend.openssl_assert(obj != backend._ffi.NULL)
oid = x509.ObjectIdentifier(_obj2txt(backend, obj))
ekus.append(oid)
return x509.ExtendedKeyUsage(ekus)
def _decode_certificate_policies(backend, cp):
cp = backend._ffi.cast("Cryptography_STACK_OF_POLICYINFO *", cp)
cp = backend._ffi.gc(cp, backend._lib.sk_POLICYINFO_free)
num = backend._lib.sk_POLICYINFO_num(cp)
certificate_policies = []
for i in range(num):
qualifiers = None
pi = backend._lib.sk_POLICYINFO_value(cp, i)
oid = x509.ObjectIdentifier(_obj2txt(backend, pi.policyid))
if pi.qualifiers != backend._ffi.NULL:
qnum = backend._lib.sk_POLICYQUALINFO_num(pi.qualifiers)
qualifiers = []
for j in range(qnum):
pqi = backend._lib.sk_POLICYQUALINFO_value(
pi.qualifiers, j
)
pqualid = x509.ObjectIdentifier(
_obj2txt(backend, pqi.pqualid)
)
if pqualid == CertificatePoliciesOID.CPS_QUALIFIER:
cpsuri = backend._ffi.buffer(
pqi.d.cpsuri.data, pqi.d.cpsuri.length
)[:].decode('ascii')
qualifiers.append(cpsuri)
else:
assert pqualid == CertificatePoliciesOID.CPS_USER_NOTICE
user_notice = _decode_user_notice(
backend, pqi.d.usernotice
)
qualifiers.append(user_notice)
certificate_policies.append(
x509.PolicyInformation(oid, qualifiers)
)
return x509.CertificatePolicies(certificate_policies)
def _decode_authority_information_access(backend, aia):
aia = backend._ffi.cast("Cryptography_STACK_OF_ACCESS_DESCRIPTION *", aia)
aia = backend._ffi.gc(aia, backend._lib.sk_ACCESS_DESCRIPTION_free)
num = backend._lib.sk_ACCESS_DESCRIPTION_num(aia)
access_descriptions = []
for i in range(num):
ad = backend._lib.sk_ACCESS_DESCRIPTION_value(aia, i)
backend.openssl_assert(ad.method != backend._ffi.NULL)
oid = x509.ObjectIdentifier(_obj2txt(backend, ad.method))
backend.openssl_assert(ad.location != backend._ffi.NULL)
gn = _decode_general_name(backend, ad.location)
access_descriptions.append(x509.AccessDescription(oid, gn))
return x509.AuthorityInformationAccess(access_descriptions)
def _decode_extended_key_usage(backend, sk):
sk = backend._ffi.cast("Cryptography_STACK_OF_ASN1_OBJECT *", sk)
sk = backend._ffi.gc(sk, backend._lib.sk_ASN1_OBJECT_free)
num = backend._lib.sk_ASN1_OBJECT_num(sk)
ekus = []
for i in range(num):
obj = backend._lib.sk_ASN1_OBJECT_value(sk, i)
backend.openssl_assert(obj != backend._ffi.NULL)
oid = x509.ObjectIdentifier(_obj2txt(backend, obj))
ekus.append(oid)
return x509.ExtendedKeyUsage(ekus)
def _decode_x509_name_entry(backend, x509_name_entry):
obj = backend._lib.X509_NAME_ENTRY_get_object(x509_name_entry)
backend.openssl_assert(obj != backend._ffi.NULL)
data = backend._lib.X509_NAME_ENTRY_get_data(x509_name_entry)
backend.openssl_assert(data != backend._ffi.NULL)
value = _asn1_string_to_utf8(backend, data)
oid = _obj2txt(backend, obj)
return x509.NameAttribute(x509.ObjectIdentifier(oid), value)
def _decode_certificate_policies(backend, cp):
cp = backend._ffi.cast("Cryptography_STACK_OF_POLICYINFO *", cp)
cp = backend._ffi.gc(cp, backend._lib.sk_POLICYINFO_free)
num = backend._lib.sk_POLICYINFO_num(cp)
certificate_policies = []
for i in range(num):
qualifiers = None
pi = backend._lib.sk_POLICYINFO_value(cp, i)
oid = x509.ObjectIdentifier(_obj2txt(backend, pi.policyid))
if pi.qualifiers != backend._ffi.NULL:
qnum = backend._lib.sk_POLICYQUALINFO_num(pi.qualifiers)
qualifiers = []
for j in range(qnum):
pqi = backend._lib.sk_POLICYQUALINFO_value(
pi.qualifiers, j
)
pqualid = x509.ObjectIdentifier(
_obj2txt(backend, pqi.pqualid)
)
if pqualid == CertificatePoliciesOID.CPS_QUALIFIER:
cpsuri = backend._ffi.buffer(
pqi.d.cpsuri.data, pqi.d.cpsuri.length
)[:].decode('ascii')
qualifiers.append(cpsuri)
else:
assert pqualid == CertificatePoliciesOID.CPS_USER_NOTICE
user_notice = _decode_user_notice(
backend, pqi.d.usernotice
)
qualifiers.append(user_notice)
certificate_policies.append(
x509.PolicyInformation(oid, qualifiers)
)
return x509.CertificatePolicies(certificate_policies)
def _decode_authority_information_access(backend, aia):
aia = backend._ffi.cast("Cryptography_STACK_OF_ACCESS_DESCRIPTION *", aia)
aia = backend._ffi.gc(aia, backend._lib.sk_ACCESS_DESCRIPTION_free)
num = backend._lib.sk_ACCESS_DESCRIPTION_num(aia)
access_descriptions = []
for i in range(num):
ad = backend._lib.sk_ACCESS_DESCRIPTION_value(aia, i)
backend.openssl_assert(ad.method != backend._ffi.NULL)
oid = x509.ObjectIdentifier(_obj2txt(backend, ad.method))
backend.openssl_assert(ad.location != backend._ffi.NULL)
gn = _decode_general_name(backend, ad.location)
access_descriptions.append(x509.AccessDescription(oid, gn))
return x509.AuthorityInformationAccess(access_descriptions)
def _decode_extended_key_usage(backend, sk):
sk = backend._ffi.cast("Cryptography_STACK_OF_ASN1_OBJECT *", sk)
sk = backend._ffi.gc(sk, backend._lib.sk_ASN1_OBJECT_free)
num = backend._lib.sk_ASN1_OBJECT_num(sk)
ekus = []
for i in range(num):
obj = backend._lib.sk_ASN1_OBJECT_value(sk, i)
backend.openssl_assert(obj != backend._ffi.NULL)
oid = x509.ObjectIdentifier(_obj2txt(backend, obj))
ekus.append(oid)
return x509.ExtendedKeyUsage(ekus)
def _decode_certificate_policies(backend, cp):
cp = backend._ffi.cast("Cryptography_STACK_OF_POLICYINFO *", cp)
cp = backend._ffi.gc(cp, backend._lib.sk_POLICYINFO_free)
num = backend._lib.sk_POLICYINFO_num(cp)
certificate_policies = []
for i in range(num):
qualifiers = None
pi = backend._lib.sk_POLICYINFO_value(cp, i)
oid = x509.ObjectIdentifier(_obj2txt(backend, pi.policyid))
if pi.qualifiers != backend._ffi.NULL:
qnum = backend._lib.sk_POLICYQUALINFO_num(pi.qualifiers)
qualifiers = []
for j in range(qnum):
pqi = backend._lib.sk_POLICYQUALINFO_value(
pi.qualifiers, j
)
pqualid = x509.ObjectIdentifier(
_obj2txt(backend, pqi.pqualid)
)
if pqualid == CertificatePoliciesOID.CPS_QUALIFIER:
cpsuri = backend._ffi.buffer(
pqi.d.cpsuri.data, pqi.d.cpsuri.length
)[:].decode('ascii')
qualifiers.append(cpsuri)
else:
assert pqualid == CertificatePoliciesOID.CPS_USER_NOTICE
user_notice = _decode_user_notice(
backend, pqi.d.usernotice
)
qualifiers.append(user_notice)
certificate_policies.append(
x509.PolicyInformation(oid, qualifiers)
)
return x509.CertificatePolicies(certificate_policies)
def _decode_authority_information_access(backend, aia):
aia = backend._ffi.cast("Cryptography_STACK_OF_ACCESS_DESCRIPTION *", aia)
aia = backend._ffi.gc(aia, backend._lib.sk_ACCESS_DESCRIPTION_free)
num = backend._lib.sk_ACCESS_DESCRIPTION_num(aia)
access_descriptions = []
for i in range(num):
ad = backend._lib.sk_ACCESS_DESCRIPTION_value(aia, i)
backend.openssl_assert(ad.method != backend._ffi.NULL)
oid = x509.ObjectIdentifier(_obj2txt(backend, ad.method))
backend.openssl_assert(ad.location != backend._ffi.NULL)
gn = _decode_general_name(backend, ad.location)
access_descriptions.append(x509.AccessDescription(oid, gn))
return x509.AuthorityInformationAccess(access_descriptions)
def _decode_extended_key_usage(backend, sk):
sk = backend._ffi.cast("Cryptography_STACK_OF_ASN1_OBJECT *", sk)
sk = backend._ffi.gc(sk, backend._lib.sk_ASN1_OBJECT_free)
num = backend._lib.sk_ASN1_OBJECT_num(sk)
ekus = []
for i in range(num):
obj = backend._lib.sk_ASN1_OBJECT_value(sk, i)
backend.openssl_assert(obj != backend._ffi.NULL)
oid = x509.ObjectIdentifier(_obj2txt(backend, obj))
ekus.append(oid)
return x509.ExtendedKeyUsage(ekus)