X.509 Reference 

Loading Certificates 

cryptography.x509. load_pem_x509_certificate ( data ) 

Added in version 0.7.

Deserialize a certificate from PEM encoded data. PEM certificates are base64 decoded and have delimiters that look like -----BEGIN CERTIFICATE----- .

Parameters :: data ( bytes ) – The PEM encoded certificate data.
Returns :: An instance of Certificate .

>>> from cryptography import x509
>>> cert = x509.load_pem_x509_certificate(pem_data)
>>> cert.serial_number
2

cryptography.x509. load_pem_x509_certificates ( data ) 

Added in version 39.0.0.

Deserialize one or more certificates from PEM encoded data.

This is like load_pem_x509_certificate() , but allows for loading multiple certificates (as adjacent PEMs) at once.

Parameters :: data ( bytes ) – One or more PEM-encoded certificates.
Returns :: list of Certificate
Raises :: ValueError – If there isn’t at least one certificate, or if any certificate is malformed.

cryptography.x509. load_der_x509_certificate ( data ) 

Added in version 0.7.

Deserialize a certificate from DER encoded data. DER is a binary format and is commonly found in files with the .cer extension (although file extensions are not a guarantee of encoding type).

Parameters :: data ( bytes ) – The DER encoded certificate data.
Returns :: An instance of Certificate .

Loading Certificate Revocation Lists 

cryptography.x509. load_pem_x509_crl ( data ) 

Added in version 1.1.

Deserialize a certificate revocation list (CRL) from PEM encoded data. PEM requests are base64 decoded and have delimiters that look like -----BEGIN X509 CRL----- .

Parameters :: data ( bytes ) – The PEM encoded request data.
Returns :: An instance of CertificateRevocationList .

>>> from cryptography import x509
>>> from cryptography.hazmat.primitives import hashes
>>> crl = x509.load_pem_x509_crl(pem_crl_data)
>>> isinstance(crl.signature_hash_algorithm, hashes.SHA256)
True

cryptography.x509. load_der_x509_crl ( data ) 

Added in version 1.1.

Deserialize a certificate revocation list (CRL) from DER encoded data. DER is a binary format.

Parameters :: data ( bytes ) – The DER encoded request data.
Returns :: An instance of CertificateRevocationList .

Loading Certificate Signing Requests 

cryptography.x509. load_pem_x509_csr ( data ) 

Added in version 0.9.

Deserialize a certificate signing request (CSR) from PEM encoded data. PEM requests are base64 decoded and have delimiters that look like -----BEGIN CERTIFICATE REQUEST----- . This format is also known as PKCS#10.

Parameters :: data ( bytes ) – The PEM encoded request data.
Returns :: An instance of CertificateSigningRequest .

>>> from cryptography import x509
>>> from cryptography.hazmat.primitives import hashes
>>> csr = x509.load_pem_x509_csr(pem_req_data)
>>> isinstance(csr.signature_hash_algorithm, hashes.SHA256)
True

cryptography.x509. load_der_x509_csr ( data ) 

Added in version 0.9.

Deserialize a certificate signing request (CSR) from DER encoded data. DER is a binary format and is not commonly used with CSRs.

Parameters :: data ( bytes ) – The DER encoded request data.
Returns :: An instance of CertificateSigningRequest .

X.509 Certificate Object 

class cryptography.x509. Certificate [source] : Added in version 0.7.

version 

Type :: Version

The certificate version as an enumeration. Version 3 certificates are the latest version and also the only type you should see in practice.

Raises :: cryptography.x509.InvalidVersion – If the version in the certificate is not a known X.509 version .

>>> cert.version
<Version.v3: 2>

fingerprint ( algorithm ) [source] 

Parameters :: algorithm – The HashAlgorithm that will be used to generate the fingerprint.
Return bytes :: The fingerprint using the supplied hash algorithm, as bytes.

>>> from cryptography.hazmat.primitives import hashes
>>> cert.fingerprint(hashes.SHA256())
b'\x86\xd2\x187Gc\xfc\xe7}[+E9\x8d\xb4\x8f\x10\xe5S\xda\x18u\xbe}a\x03\x08[\xac\xa04?'

serial_number 

Type :: int

The serial as a Python integer.

>>> cert.serial_number
2

public_key ( ) [source] 

The public key associated with the certificate.

Returns :: One of CertificatePublicKeyTypes .

>>> from cryptography.hazmat.primitives.asymmetric import rsa
>>> public_key = cert.public_key()
>>> isinstance(public_key, rsa.RSAPublicKey)
True

not_valid_before 

Type :: datetime.datetime

Warning

This property is deprecated and will be removed in a future version. Please switch to the timezone-aware variant not_valid_before_utc() .

A naïve datetime representing the beginning of the validity period for the certificate in UTC. This value is inclusive.

>>> cert.not_valid_before
datetime.datetime(2010, 1, 1, 8, 30)

not_valid_before_utc 

Added in version 42.0.0.

Type :: datetime.datetime

A timezone-aware datetime representing the beginning of the validity period for the certificate in UTC. This value is inclusive.

>>> cert.not_valid_before_utc
datetime.datetime(2010, 1, 1, 8, 30, tzinfo=datetime.timezone.utc)

not_valid_after 

Type :: datetime.datetime

Warning

This property is deprecated and will be removed in a future version. Please switch to the timezone-aware variant not_valid_after_utc() .

A naïve datetime representing the end of the validity period for the certificate in UTC. This value is inclusive.

>>> cert.not_valid_after
datetime.datetime(2030, 12, 31, 8, 30)

not_valid_after_utc 

Added in version 42.0.0.

Type :: datetime.datetime

A timezone-aware datetime representing the end of the validity period for the certificate in UTC. This value is inclusive.

>>> cert.not_valid_after_utc
datetime.datetime(2030, 12, 31, 8, 30, tzinfo=datetime.timezone.utc)

issuer 

Added in version 0.8.

Type :: Name

The Name of the issuer.

subject 

Added in version 0.8.

Type :: Name

The Name of the subject.

signature_hash_algorithm 

Type :: HashAlgorithm

Returns the HashAlgorithm which was used in signing this certificate. Can be None if signature did not use separate hash ( ED25519 , ED448 ).

>>> from cryptography.hazmat.primitives import hashes
>>> isinstance(cert.signature_hash_algorithm, hashes.SHA256)
True

signature_algorithm_oid 

Added in version 1.6.

Type :: ObjectIdentifier

Returns the ObjectIdentifier of the signature algorithm used to sign the certificate. This will be one of the OIDs from SignatureAlgorithmOID .

>>> cert.signature_algorithm_oid
<ObjectIdentifier(oid=1.2.840.113549.1.1.11, name=sha256WithRSAEncryption)>

signature_algorithm_parameters 

Added in version 41.0.0.

Returns the parameters of the signature algorithm used to sign the certificate. For RSA signatures it will return either a PKCS1v15 or PSS object.

For ECDSA signatures it will return an ECDSA .

For EdDSA and DSA signatures it will return None .

These objects can be used to verify signatures on the certificate.

Returns :: None, PKCS1v15 , PSS , or ECDSA

>>> from cryptography.hazmat.primitives.asymmetric import padding
>>> pss_cert = x509.load_pem_x509_certificate(rsa_pss_pem_cert)
>>> isinstance(pss_cert.signature_algorithm_parameters, padding.PSS)
True

extensions 

Type :: Extensions

The extensions encoded in the certificate.

Raises :

cryptography.x509.DuplicateExtension – If more than one extension of the same type is found within the certificate.
cryptography.x509.UnsupportedGeneralNameType – If an extension contains a general name that is not supported.

>>> for ext in cert.extensions:
...     print(ext)
<Extension(oid=<ObjectIdentifier(oid=2.5.29.35, name=authorityKeyIdentifier)>, critical=False, value=<AuthorityKeyIdentifier(key_identifier=b'\xe4}_\xd1\\\x95\x86\x08,\x05\xae\xbeu\xb6e\xa7\xd9]\xa8f', authority_cert_issuer=None, authority_cert_serial_number=None)>)>
<Extension(oid=<ObjectIdentifier(oid=2.5.29.14, name=subjectKeyIdentifier)>, critical=False, value=<SubjectKeyIdentifier(digest=b'X\x01\x84$\x1b\xbc+R\x94J=\xa5\x10r\x14Q\xf5\xaf:\xc9')>)>
<Extension(oid=<ObjectIdentifier(oid=2.5.29.15, name=keyUsage)>, critical=True, value=<KeyUsage(digital_signature=False, content_commitment=False, key_encipherment=False, data_encipherment=False, key_agreement=False, key_cert_sign=True, crl_sign=True, encipher_only=False, decipher_only=False)>)>
<Extension(oid=<ObjectIdentifier(oid=2.5.29.32, name=certificatePolicies)>, critical=False, value=<CertificatePolicies([<PolicyInformation(policy_identifier=<ObjectIdentifier(oid=2.16.840.1.101.3.2.1.48.1, name=Unknown OID)>, policy_qualifiers=None)>])>)>
<Extension(oid=<ObjectIdentifier(oid=2.5.29.19, name=basicConstraints)>, critical=True, value=<BasicConstraints(ca=True, path_length=None)>)>

signature 

Added in version 1.2.

Type :: bytes

The bytes of the certificate’s signature.

tbs_certificate_bytes 

Added in version 1.2.

type :

bytes

The DER encoded bytes payload (as defined by RFC 5280 ) that is hashed and then signed by the private key of the certificate’s issuer. This data may be used to validate a signature, but use extreme caution as certificate validation is a complex problem that involves much more than just signature checks.

To validate the signature on a certificate you can do the following. Note: This only verifies that the certificate was signed with the private key associated with the public key provided and does not perform any of the other checks needed for secure certificate validation. Additionally, this example will only work for RSA public keys with PKCS1v15 signatures, and so it can’t be used for general purpose signature verification.
>>> from cryptography.hazmat.primitives.serialization import load_pem_public_key
>>> from cryptography.hazmat.primitives.asymmetric import padding
>>> issuer_public_key = load_pem_public_key(pem_issuer_public_key)
>>> cert_to_check = x509.load_pem_x509_certificate(pem_data_to_check)
>>> issuer_public_key.verify(
...     cert_to_check.signature,
...     cert_to_check.tbs_certificate_bytes,
...     # Depends on the algorithm used to create the certificate
...     padding.PKCS1v15(),
...     cert_to_check.signature_hash_algorithm,
... )

An InvalidSignature exception will be raised if the signature fails to verify.

verify_directly_issued_by ( issuer ) [source] 

Added in version 40.0.0.

Parameters :: issuer ( Certificate ) – The issuer certificate to check against.

Warning

This method verifies that the certificate issuer name matches the issuer subject name and that the certificate is signed by the issuer’s private key. No other validation is performed. Callers are responsible for performing any additional validations required for their use case (e.g. checking the validity period, whether the signer is allowed to issue certificates, that the issuing certificate has a strong public key, etc).

Validates that the certificate is signed by the provided issuer and that the issuer’s subject name matches the issuer name of the certificate.

Returns :

None

Raises :

ValueError – If the issuer name on the certificate does not match the subject name of the issuer or the signature algorithm is unsupported.
TypeError – If the issuer does not have a supported public key type.
cryptography.exceptions.InvalidSignature – If the signature fails to verify.

tbs_precertificate_bytes 

Added in version 38.0.0.

Type :: bytes
Raises :: ValueError – If the certificate doesn’t have the expected Certificate Transparency extensions.

The DER encoded bytes payload (as defined by RFC 6962 ) that is hashed and then signed by the private key of the pre-certificate’s issuer. This data may be used to validate a Signed Certificate Timestamp’s signature, but use extreme caution as SCT validation is a complex problem that involves much more than just signature checks.

This method is primarily useful in the context of programs that interact with and verify the products of Certificate Transparency logs, as specified in RFC 6962 . If you are not directly interacting with a Certificate Transparency log, this method unlikely to be what you want. To make unintentional misuse less likely, it raises a ValueError if the underlying certificate does not contain the expected Certificate Transparency extensions.

public_bytes ( encoding ) [source] 

Added in version 1.0.

Parameters :: encoding – The Encoding that will be used to serialize the certificate.
Return bytes :: The data that can be written to a file or sent over the network to be verified by clients.

X.509 CRL (Certificate Revocation List) Object 

class cryptography.x509. CertificateRevocationList [source] 

Added in version 1.0.

A CertificateRevocationList is an object representing a list of revoked certificates. The object is iterable and will yield the RevokedCertificate objects stored in this CRL.

>>> len(crl)
1
>>> revoked_certificate = crl[0]
>>> type(revoked_certificate)
<class '...RevokedCertificate'>
>>> for r in crl:
...     print(r.serial_number)
0

fingerprint ( algorithm ) [source] 

Parameters :: algorithm – The HashAlgorithm that will be used to generate the fingerprint.
Return bytes :: The fingerprint using the supplied hash algorithm, as bytes.

>>> from cryptography.hazmat.primitives import hashes
>>> crl.fingerprint(hashes.SHA256())
b'\xe3\x1d\xb5P\x18\x9ed\x9f\x16O\x9dm\xc1>\x8c\xca\xb1\xc6x?T\x9f\xe9t_\x1d\x8dF8V\xf78'

get_revoked_certificate_by_serial_number ( serial_number ) [source] 

Added in version 2.3.

Parameters :: serial_number – The serial as a Python integer.
Returns :: RevokedCertificate if the serial_number is present in the CRL or None if it is not.

signature_hash_algorithm 

Type :: HashAlgorithm

Returns the HashAlgorithm which was used in signing this CRL. Can be None if signature did not use separate hash ( ED25519 , ED448 ).

>>> from cryptography.hazmat.primitives import hashes
>>> isinstance(crl.signature_hash_algorithm, hashes.SHA256)
True

signature_algorithm_oid 

Added in version 1.6.

Type :: ObjectIdentifier

Returns the ObjectIdentifier of the signature algorithm used to sign the CRL. This will be one of the OIDs from SignatureAlgorithmOID .

>>> crl.signature_algorithm_oid
<ObjectIdentifier(oid=1.2.840.113549.1.1.11, name=sha256WithRSAEncryption)>

signature_algorithm_parameters 

Added in version 42.0.0.

Returns the parameters of the signature algorithm used to sign the certificate revocation list. For RSA signatures it will return either a PKCS1v15 or PSS object.

For ECDSA signatures it will return an ECDSA .

For EdDSA and DSA signatures it will return None .

These objects can be used to verify the CRL signature.

Returns :: None, PKCS1v15 , PSS , or ECDSA

issuer 

Type :: Name

The Name of the issuer.

>>> crl.issuer
<Name(C=US,CN=cryptography.io)>

next_update 

Type :: datetime.datetime

Warning

This property is deprecated and will be removed in a future version. Please switch to the timezone-aware variant next_update_utc() .

A naïve datetime representing when the next update to this CRL is expected.

>>> crl.next_update
datetime.datetime(2016, 1, 1, 0, 0)

next_update_utc 

Added in version 42.0.0.

Type :: datetime.datetime

A timezone-aware datetime representing when the next update to this CRL is expected.

>>> crl.next_update_utc
datetime.datetime(2016, 1, 1, 0, 0, tzinfo=datetime.timezone.utc)

last_update 

Type :: datetime.datetime

Warning

This property is deprecated and will be removed in a future version. Please switch to the timezone-aware variant last_update_utc() .

A naïve datetime representing when this CRL was last updated.

>>> crl.last_update
datetime.datetime(2015, 1, 1, 0, 0)

last_update_utc 

Added in version 42.0.0.

Type :: datetime.datetime

A timezone-aware datetime representing when this CRL was last updated.

>>> crl.last_update_utc
datetime.datetime(2015, 1, 1, 0, 0, tzinfo=datetime.timezone.utc)

extensions 

Type :: Extensions

The extensions encoded in the CRL.

signature 

Added in version 1.2.

Type :: bytes

The bytes of the CRL’s signature.

tbs_certlist_bytes 

Added in version 1.2.

Type :: bytes

The DER encoded bytes payload (as defined by RFC 5280 ) that is hashed and then signed by the private key of the CRL’s issuer. This data may be used to validate a signature, but use extreme caution as CRL validation is a complex problem that involves much more than just signature checks.

public_bytes ( encoding ) [source] 

Added in version 1.2.

Parameters :: encoding – The Encoding that will be used to serialize the certificate revocation list.
Return bytes :: The data that can be written to a file or sent over the network and used as part of a certificate verification process.

is_signature_valid ( public_key ) [source] : Added in version 2.1.

Warning

Checking the validity of the signature on the CRL is insufficient to know if the CRL should be trusted. More details are available in RFC 5280 .

Returns True if the CRL signature is correct for given public key, False otherwise.

X.509 Certificate Builder 

class cryptography.x509. CertificateBuilder [source] 

Added in version 1.0.

>>> from cryptography import x509
>>> from cryptography.hazmat.primitives import hashes
>>> from cryptography.hazmat.primitives.asymmetric import rsa
>>> from cryptography.x509.oid import NameOID
>>> import datetime
>>> one_day = datetime.timedelta(1, 0, 0)
>>> private_key = rsa.generate_private_key(
...     public_exponent=65537,
...     key_size=2048,
... )
>>> public_key = private_key.public_key()
>>> builder = x509.CertificateBuilder()
>>> builder = builder.subject_name(x509.Name([
...     x509.NameAttribute(NameOID.COMMON_NAME, 'cryptography.io'),
... ]))
>>> builder = builder.issuer_name(x509.Name([
...     x509.NameAttribute(NameOID.COMMON_NAME, 'cryptography.io'),
... ]))
>>> builder = builder.not_valid_before(datetime.datetime.today() - one_day)
>>> builder = builder.not_valid_after(datetime.datetime.today() + (one_day * 30))
>>> builder = builder.serial_number(x509.random_serial_number())
>>> builder = builder.public_key(public_key)
>>> builder = builder.add_extension(
...     x509.SubjectAlternativeName(
...         [x509.DNSName('cryptography.io')]
...     ),
...     critical=False
... )
>>> builder = builder.add_extension(
...     x509.BasicConstraints(ca=False, path_length=None), critical=True,
... )
>>> certificate = builder.sign(
...     private_key=private_key, algorithm=hashes.SHA256(),
... )
>>> isinstance(certificate, x509.Certificate)
True

issuer_name ( name ) [source] 

Sets the issuer’s distinguished name.

Parameters :: name – The Name that describes the issuer (CA).

subject_name ( name ) [source] 

Sets the subject’s distinguished name.

Parameters :: name – The Name that describes the subject.

public_key ( public_key ) [source] 

Sets the subject’s public key.

Parameters :: public_key – The subject’s public key. This can be one of CertificatePublicKeyTypes .

serial_number ( serial_number ) [source] 

Sets the certificate’s serial number (an integer). The CA’s policy determines how it attributes serial numbers to certificates. This number must uniquely identify the certificate given the issuer. CABForum Guidelines require entropy in the serial number to provide protection against hash collision attacks. For more information on secure random number generation, see Random number generation .

Parameters :: serial_number – Integer number that will be used by the CA to identify this certificate (most notably during certificate revocation checking). Users should consider using random_serial_number() when possible.

not_valid_before ( time ) [source] 

Sets the certificate’s activation time. This is the time from which clients can start trusting the certificate. It may be different from the time at which the certificate was created.

Parameters :: time – The datetime.datetime object (in UTC) that marks the activation time for the certificate. The certificate may not be trusted clients if it is used before this time.

not_valid_after ( time ) [source] 

Sets the certificate’s expiration time. This is the time from which clients should no longer trust the certificate. The CA’s policy will determine how long the certificate should remain in use.

Parameters :: time – The datetime.datetime object (in UTC) that marks the expiration time for the certificate. The certificate may not be trusted clients if it is used after this time.

add_extension ( extval , critical ) [source] 

Adds an X.509 extension to the certificate.

Parameters :

extval – An extension conforming to the ExtensionType interface.
critical – Set to True if the extension must be understood and handled by whoever reads the certificate.

sign ( private_key , algorithm , * , rsa_padding = None ) [source] 

Sign the certificate using the CA’s private key.

Parameters :

private_key – The key that will be used to sign the certificate, one of CertificateIssuerPrivateKeyTypes .
algorithm – The HashAlgorithm that will be used to generate the signature. This must be None if the private_key is an Ed25519PrivateKey or an Ed448PrivateKey and an instance of a HashAlgorithm otherwise.
rsa_padding ( None , PKCS1v15 , or PSS ) –
Added in version 41.0.0.

This is a keyword-only argument. If private_key is an RSAPrivateKey then this can be set to either PKCS1v15 or PSS to sign with those respective paddings. If this is None then RSA keys will default to PKCS1v15 padding. All other key types must not pass a value other than None .

Returns :

Certificate

X.509 CSR (Certificate Signing Request) Object 

class cryptography.x509. CertificateSigningRequest [source] 

Added in version 0.9.

public_key ( ) [source] 

The public key associated with the request.

Returns :: One of CertificatePublicKeyTypes .

>>> from cryptography.hazmat.primitives.asymmetric import rsa
>>> public_key = csr.public_key()
>>> isinstance(public_key, rsa.RSAPublicKey)
True

subject 

Type :: Name

The Name of the subject.

signature_hash_algorithm 

Type :: HashAlgorithm

Returns the HashAlgorithm which was used in signing this request. Can be None if signature did not use separate hash ( ED25519 , ED448 ).

>>> from cryptography.hazmat.primitives import hashes
>>> isinstance(csr.signature_hash_algorithm, hashes.SHA256)
True

signature_algorithm_oid 

Added in version 1.6.

Type :: ObjectIdentifier

Returns the ObjectIdentifier of the signature algorithm used to sign the request. This will be one of the OIDs from SignatureAlgorithmOID .

>>> csr.signature_algorithm_oid
<ObjectIdentifier(oid=1.2.840.113549.1.1.11, name=sha256WithRSAEncryption)>

signature_algorithm_parameters 

Added in version 42.0.0.

Returns the parameters of the signature algorithm used to sign the certificate signing request. For RSA signatures it will return either a PKCS1v15 or PSS object.

For ECDSA signatures it will return an ECDSA .

For EdDSA and DSA signatures it will return None .

These objects can be used to verify signatures on the signing request.

Returns :: None, PKCS1v15 , PSS , or ECDSA

extensions 

Type :: Extensions

The extensions encoded in the certificate signing request.

Raises :

cryptography.x509.DuplicateExtension – If more than one extension of the same type is found within the certificate signing request.
cryptography.x509.UnsupportedGeneralNameType – If an extension contains a general name that is not supported.

attributes 

Added in version 36.0.0.

Type :: Attributes

The attributes encoded in the certificate signing request.

public_bytes ( encoding ) [source] 

Added in version 1.0.

Parameters :: encoding – The Encoding that will be used to serialize the certificate request.
Return bytes :: The data that can be written to a file or sent over the network to be signed by the certificate authority.

signature 

Added in version 1.2.

Type :: bytes

The bytes of the certificate signing request’s signature.

tbs_certrequest_bytes 

Added in version 1.2.

Type :: bytes

The DER encoded bytes payload (as defined by RFC 2986 ) that is hashed and then signed by the private key (corresponding to the public key embedded in the CSR). This data may be used to validate the CSR signature.

is_signature_valid 

Added in version 1.3.

Returns True if the CSR signature is correct, False otherwise.

X.509 Certificate Revocation List Builder 

class cryptography.x509. CertificateRevocationListBuilder [source] 

Added in version 1.2.

>>> from cryptography import x509
>>> from cryptography.hazmat.primitives import hashes
>>> from cryptography.hazmat.primitives.asymmetric import rsa
>>> from cryptography.x509.oid import NameOID
>>> import datetime
>>> one_day = datetime.timedelta(1, 0, 0)
>>> private_key = rsa.generate_private_key(
...     public_exponent=65537,
...     key_size=2048,
... )
>>> builder = x509.CertificateRevocationListBuilder()
>>> builder = builder.issuer_name(x509.Name([
...     x509.NameAttribute(NameOID.COMMON_NAME, 'cryptography.io CA'),
... ]))
>>> builder = builder.last_update(datetime.datetime.today())
>>> builder = builder.next_update(datetime.datetime.today() + one_day)
>>> revoked_cert = x509.RevokedCertificateBuilder().serial_number(
...     333
... ).revocation_date(
...     datetime.datetime.today()
... ).build()
>>> builder = builder.add_revoked_certificate(revoked_cert)
>>> crl = builder.sign(
...     private_key=private_key, algorithm=hashes.SHA256(),
... )
>>> len(crl)
1

issuer_name ( name ) [source] 

Sets the issuer’s distinguished name.

Parameters :: name – The Name that describes the issuer (CA).

last_update ( time ) [source] 

Sets this CRL’s activation time. This is the time from which clients can start trusting this CRL. It may be different from the time at which this CRL was created. This is also known as the thisUpdate time.

Parameters :: time – The datetime.datetime object (in UTC) that marks the activation time for this CRL. The CRL may not be trusted if it is used before this time.

next_update ( time ) [source] 

Sets this CRL’s next update time. This is the time by which a new CRL will be issued. The CA is allowed to issue a new CRL before this date, however clients are not required to check for it.

Parameters :: time – The datetime.datetime object (in UTC) that marks the next update time for this CRL.

add_extension ( extval , critical ) [source] 

Adds an X.509 extension to this CRL.

Parameters :

extval – An extension with the ExtensionType interface.
critical – Set to True if the extension must be understood and handled by whoever reads the CRL.

add_revoked_certificate ( revoked_certificate ) [source] 

Adds a revoked certificate to this CRL.

Parameters :: revoked_certificate – An instance of RevokedCertificate . These can be obtained from an existing CRL or created with RevokedCertificateBuilder .

sign ( private_key , algorithm , * , rsa_padding = None ) [source] 

Sign this CRL using the CA’s private key.

Parameters :

private_key – The private key that will be used to sign the certificate, one of CertificateIssuerPrivateKeyTypes .
algorithm – The HashAlgorithm that will be used to generate the signature. This must be None if the private_key is an Ed25519PrivateKey or an Ed448PrivateKey and an instance of a HashAlgorithm otherwise.
rsa_padding ( None , PKCS1v15 , or PSS ) –
Added in version 42.0.0.

This is a keyword-only argument. If private_key is an RSAPrivateKey then this can be set to either PKCS1v15 or PSS to sign with those respective paddings. If this is None then RSA keys will default to PKCS1v15 padding. All other key types must not pass a value other than None .

Returns :

CertificateRevocationList

X.509 Revoked Certificate Object 

class cryptography.x509. RevokedCertificate [source] 

Added in version 1.0.

serial_number 

Type :: int

An integer representing the serial number of the revoked certificate.

>>> revoked_certificate.serial_number
0

revocation_date 

Type :: datetime.datetime

Warning

This property is deprecated and will be removed in a future version. Please switch to the timezone-aware variant revocation_date_utc() .

A naïve datetime representing the date this certificates was revoked.

>>> revoked_certificate.revocation_date
datetime.datetime(2015, 1, 1, 0, 0)

revocation_date_utc 

Added in version 42.0.0.

Type :: datetime.datetime

A timezone-aware datetime representing the date this certificates was revoked.

>>> revoked_certificate.revocation_date_utc
datetime.datetime(2015, 1, 1, 0, 0, tzinfo=datetime.timezone.utc)

extensions 

Type :: Extensions

The extensions encoded in the revoked certificate.

>>> for ext in revoked_certificate.extensions:
...     print(ext)
<Extension(oid=<ObjectIdentifier(oid=2.5.29.24, name=invalidityDate)>, critical=False, value=<InvalidityDate(invalidity_date=2015-01-01 00:00:00)>)>
<Extension(oid=<ObjectIdentifier(oid=2.5.29.21, name=cRLReason)>, critical=False, value=<CRLReason(reason=ReasonFlags.key_compromise)>)>

X.509 Revoked Certificate Builder 

class cryptography.x509. RevokedCertificateBuilder [source] 

This class is used to create RevokedCertificate objects that can be used with the CertificateRevocationListBuilder .

Added in version 1.2.

>>> from cryptography import x509
>>> import datetime
>>> builder = x509.RevokedCertificateBuilder()
>>> builder = builder.revocation_date(datetime.datetime.today())
>>> builder = builder.serial_number(3333)
>>> revoked_certificate = builder.build()
>>> isinstance(revoked_certificate, x509.RevokedCertificate)
True

serial_number ( serial_number ) [source] 

Sets the revoked certificate’s serial number.

Parameters :: serial_number – Integer number that is used to identify the revoked certificate.

revocation_date ( time ) [source] 

Sets the certificate’s revocation date.

Parameters :: time – The datetime.datetime object (in UTC) that marks the revocation time for the certificate.

add_extension ( extval , critical ) [source] 

Adds an X.509 extension to this revoked certificate.

Parameters :

extval – An instance of one of the CRL entry extensions .
critical – Set to True if the extension must be understood and handled.

build ( ) [source] 

Create a revoked certificate object.

Returns :: RevokedCertificate

X.509 CSR (Certificate Signing Request) Builder Object 

class cryptography.x509. CertificateSigningRequestBuilder [source] 

Added in version 1.0.

>>> from cryptography import x509
>>> from cryptography.hazmat.primitives import hashes
>>> from cryptography.hazmat.primitives.asymmetric import rsa
>>> from cryptography.x509.oid import AttributeOID, NameOID
>>> private_key = rsa.generate_private_key(
...     public_exponent=65537,
...     key_size=2048,
... )
>>> builder = x509.CertificateSigningRequestBuilder()
>>> builder = builder.subject_name(x509.Name([
...     x509.NameAttribute(NameOID.COMMON_NAME, 'cryptography.io'),
... ]))
>>> builder = builder.add_extension(
...     x509.BasicConstraints(ca=False, path_length=None), critical=True,
... )
>>> builder = builder.add_attribute(
...     AttributeOID.CHALLENGE_PASSWORD, b"changeit"
... )
>>> request = builder.sign(
...     private_key, hashes.SHA256()
... )
>>> isinstance(request, x509.CertificateSigningRequest)
True

subject_name ( name ) [source] 

Parameters :: name – The Name of the certificate subject.
Returns :: A new CertificateSigningRequestBuilder .

add_extension ( extension , critical ) [source] 

Parameters :

extension – An extension conforming to the ExtensionType interface.
critical – Set to True if the extension must be understood and handled by whoever reads the certificate.

Returns :

A new CertificateSigningRequestBuilder .

add_attribute ( oid , value ) [source] 

Added in version 3.0.

Parameters :

oid – An ObjectIdentifier instance.
value ( bytes ) – The value of the attribute.

Returns :

A new CertificateSigningRequestBuilder .

sign ( private_key , algorithm , * , rsa_padding = None ) [source] 

Parameters :

private_key – The private key that will be used to sign the request. When the request is signed by a certificate authority, the private key’s associated public key will be stored in the resulting certificate. One of CertificateIssuerPrivateKeyTypes .
algorithm – The HashAlgorithm that will be used to generate the request signature. This must be None if the private_key is an Ed25519PrivateKey or an Ed448PrivateKey and an instance of a HashAlgorithm otherwise.
rsa_padding ( None , PKCS1v15 , or PSS ) –
Added in version 42.0.0.

This is a keyword-only argument. If private_key is an RSAPrivateKey then this can be set to either PKCS1v15 or PSS to sign with those respective paddings. If this is None then RSA keys will default to PKCS1v15 padding. All other key types must not pass a value other than None .

Returns :

A new CertificateSigningRequest .

class cryptography.x509. Name [source] 

Added in version 0.8.

An X509 Name is an ordered list of attributes. The object is iterable to get every attribute or you can use Name.get_attributes_for_oid() to obtain the specific type you want. Names are sometimes represented as a slash or comma delimited string (e.g. /CN=mydomain.com/O=My Org/C=US or CN=mydomain.com,O=My Org,C=US ).

Technically, a Name is a list of sets of attributes, called Relative Distinguished Names or RDNs , although multi-valued RDNs are rarely encountered. The iteration order of values within a multi-valued RDN is preserved. If you need to handle multi-valued RDNs, the rdns property gives access to an ordered list of RelativeDistinguishedName objects.

A Name can be initialized with an iterable of NameAttribute (the common case where each RDN has a single attribute) or an iterable of RelativeDistinguishedName objects (in the rare case of multi-valued RDNs).

>>> len(cert.subject)
3
>>> for attribute in cert.subject:
...     print(attribute)
<NameAttribute(oid=<ObjectIdentifier(oid=2.5.4.6, name=countryName)>, value='US')>
<NameAttribute(oid=<ObjectIdentifier(oid=2.5.4.10, name=organizationName)>, value='Test Certificates 2011')>
<NameAttribute(oid=<ObjectIdentifier(oid=2.5.4.3, name=commonName)>, value='Good CA')>

rdns 

Added in version 1.6.

Type :: list of RelativeDistinguishedName

classmethod from_rfc4514_string ( data , attr_name_overrides = None ) [source] 

Parameters :

data ( str ) – An RFC 4514 string.
attr_name_overrides – Specify custom OID to name mappings, which can be used to match vendor-specific extensions. See NameOID for common attribute OIDs.

Returns :

A Name parsed from data .

>>> x509.Name.from_rfc4514_string("CN=cryptography.io")
<Name(CN=cryptography.io)>
>>> x509.Name.from_rfc4514_string("E=pyca@cryptography.io", {"E": NameOID.EMAIL_ADDRESS})
<Name(1.2.840.113549.1.9.1=pyca@cryptography.io)>

get_attributes_for_oid ( oid ) [source] 

Parameters :: oid – An ObjectIdentifier instance.
Returns :: A list of NameAttribute instances that match the OID provided. If nothing matches an empty list will be returned.

>>> cert.subject.get_attributes_for_oid(NameOID.COMMON_NAME)
[<NameAttribute(oid=<ObjectIdentifier(oid=2.5.4.3, name=commonName)>, value='Good CA')>]

public_bytes ( ) [source] 

Added in version 1.6.

Return bytes :: The DER encoded name.

rfc4514_string ( attr_name_overrides = None ) [source] 

Added in version 2.5.

Changed in version 36.0.0: Added attr_name_overrides parameter.

Format the given name as a RFC 4514 Distinguished Name string, for example CN=mydomain.com,O=My Org,C=US .

By default, attributes CN , L , ST , O , OU , C , STREET , DC , UID are represented by their short name. Unrecognized attributes are formatted as dotted OID strings.

Example:

>>> name = x509.Name([
...     x509.NameAttribute(NameOID.EMAIL_ADDRESS, "santa@north.pole"),
...     x509.NameAttribute(NameOID.COMMON_NAME, "Santa Claus"),
... ])
>>> name.rfc4514_string()
'CN=Santa Claus,1.2.840.113549.1.9.1=santa@north.pole'
>>> name.rfc4514_string({NameOID.EMAIL_ADDRESS: "E"})
'CN=Santa Claus,E=santa@north.pole'

Parameters :: attr_name_overrides (Dict-like mapping from ObjectIdentifier to str ) – Specify custom OID to name mappings, which can be used to match vendor-specific extensions. See NameOID for common attribute OIDs.
Return type :: str

class cryptography.x509. Version [source] 

Added in version 0.7.

An enumeration for X.509 versions.

v1 : For version 1 X.509 certificates.

v3 : For version 3 X.509 certificates.

class cryptography.x509. NameAttribute [source] 

Added in version 0.8.

An X.509 name consists of a list of RelativeDistinguishedName instances, which consist of a set of NameAttribute instances.

oid 

Type :: ObjectIdentifier

The attribute OID.

value 

Type :: str or bytes

The value of the attribute. This will generally be a str , the only times it can be a bytes is when oid is X500_UNIQUE_IDENTIFIER .

rfc4514_attribute_name 

Added in version 35.0.0.

Type :: str

The RFC 4514 short attribute name (for example “CN”), or the OID dotted string if a short name is unavailable.

rfc4514_string ( attr_name_overrides = None ) [source] 

Added in version 2.5.

Changed in version 36.0.0: Added attr_name_overrides parameter.

Return str :: Format the given attribute as a RFC 4514 Distinguished Name string.
Parameters :: attr_name_overrides (Dict-like mapping from ObjectIdentifier to str ) – Specify custom OID to name mappings, which can be used to match vendor-specific extensions.

class cryptography.x509. RelativeDistinguishedName ( attributes ) [source] 

Added in version 1.6.

A relative distinguished name is a non-empty set of name attributes. The object is iterable to get every attribute, preserving the original order. Passing duplicate attributes to the constructor raises ValueError .

get_attributes_for_oid ( oid ) [source] 

Parameters :: oid – An ObjectIdentifier instance.
Returns :: A list of NameAttribute instances that match the OID provided. The list should contain zero or one values.

rfc4514_string ( attr_name_overrides = None ) [source] 

Added in version 2.5.

Changed in version 36.0.0: Added attr_name_overrides parameter.

Return str :: Format the given RDN set as a RFC 4514 Distinguished Name string.
Parameters :: attr_name_overrides (Dict-like mapping from ObjectIdentifier to str ) – Specify custom OID to name mappings, which can be used to match vendor-specific extensions.

class cryptography.x509. ObjectIdentifier 

Added in version 0.8.

Object identifiers (frequently seen abbreviated as OID) identify the type of a value (see: NameAttribute ).

dotted_string 

Type :: str

The dotted string value of the OID (e.g. "2.5.4.3" )

General Name Classes 

class cryptography.x509. GeneralName [source] 

Added in version 0.9.

This is the generic interface that all the following classes are registered against.

class cryptography.x509. RFC822Name ( value ) [source] 

Added in version 0.9.

Changed in version 3.1: U-label support has been removed. Encode them to A-label before use.

This corresponds to an email address. For example, user@example.com .

Parameters :: value – The email address. If the address contains an internationalized domain name then it must be encoded to an A-label string before being passed.
Raises :: ValueError – If the provided string is not an A-label .

value 

Type :: str

class cryptography.x509. DNSName ( value ) [source] 

Added in version 0.9.

Changed in version 3.1: U-label support has been removed. Encode them to A-label before use.

This corresponds to a domain name. For example, cryptography.io .

Parameters :

value – The domain name. If it is an internationalized domain name then it must be encoded to an A-label string before being passed.

Raises :

ValueError –

If the provided string is not an A-label .

type :: str

value 

Type :: str

class cryptography.x509. DirectoryName ( value ) [source] 

Added in version 0.9.

This corresponds to a directory name.

value 

Type :: Name

class cryptography.x509. UniformResourceIdentifier ( value ) [source] 

Added in version 0.9.

Changed in version 3.1: U-label support has been removed. Encode them to A-label before use.

This corresponds to a uniform resource identifier. For example, https://cryptography.io .

Parameters :: value – The URI. If it contains an internationalized domain name then it must be encoded to an A-label string before being passed.
Raises :: ValueError – If the provided string is not an A-label .

value 

Type :: str

class cryptography.x509. IPAddress ( value ) [source] 

Added in version 0.9.

This corresponds to an IP address.

value 

Type :: IPv4Address , IPv6Address , IPv4Network , or IPv6Network .

class cryptography.x509. RegisteredID ( value ) [source] 

Added in version 0.9.

This corresponds to a registered ID.

value 

Type :: ObjectIdentifier

class cryptography.x509. OtherName ( type_id , value ) [source] 

Added in version 1.0.

This corresponds to an otherName. An otherName has a type identifier and a value represented in binary DER format.

type_id 

Type :: ObjectIdentifier

value 

Type :: bytes

X.509 Extensions 

class cryptography.x509. Extensions [source] 

Added in version 0.9.

An X.509 Extensions instance is an ordered list of extensions. The object is iterable to get every extension.

get_extension_for_oid ( oid ) [source] 

Parameters :: oid – An ObjectIdentifier instance.
Returns :: An instance of Extension .
Raises :: cryptography.x509.ExtensionNotFound – If the certificate does not have the extension requested.

>>> from cryptography.x509.oid import ExtensionOID
>>> cert.extensions.get_extension_for_oid(ExtensionOID.BASIC_CONSTRAINTS)
<Extension(oid=<ObjectIdentifier(oid=2.5.29.19, name=basicConstraints)>, critical=True, value=<BasicConstraints(ca=True, path_length=None)>)>

get_extension_for_class ( extclass ) [source] 

Added in version 1.1.

Parameters :: extclass – An extension class.
Returns :: An instance of Extension .
Raises :: cryptography.x509.ExtensionNotFound – If the certificate does not have the extension requested.

>>> from cryptography import x509
>>> cert.extensions.get_extension_for_class(x509.BasicConstraints)
<Extension(oid=<ObjectIdentifier(oid=2.5.29.19, name=basicConstraints)>, critical=True, value=<BasicConstraints(ca=True, path_length=None)>)>

class cryptography.x509. Extension [source] 

Added in version 0.9.

oid 

Type :: ObjectIdentifier

One of the ExtensionOID OIDs.

critical 

Type :: bool

Determines whether a given extension is critical or not. RFC 5280 requires that “A certificate-using system MUST reject the certificate if it encounters a critical extension it does not recognize or a critical extension that contains information that it cannot process”.

value : Returns an instance of the extension type corresponding to the OID.

class cryptography.x509. ExtensionType [source] 

Added in version 1.0.

This is the interface against which all the following extension types are registered.

oid 

Type :: ObjectIdentifier

Returns the OID associated with the given extension type.

public_bytes ( ) [source] 

Added in version 36.0.0.

Return bytes :: A bytes string representing the extension’s DER encoded value.

class cryptography.x509. KeyUsage ( digital_signature , content_commitment , key_encipherment , data_encipherment , key_agreement , key_cert_sign , crl_sign , encipher_only , decipher_only ) [source] 

Added in version 0.9.

The key usage extension defines the purpose of the key contained in the certificate. The usage restriction might be employed when a key that could be used for more than one operation is to be restricted.

oid 

Added in version 1.0.

Type :: ObjectIdentifier

Returns KEY_USAGE .

digital_signature 

Type :: bool

This purpose is set to true when the subject public key is used for verifying digital signatures, other than signatures on certificates ( key_cert_sign ) and CRLs ( crl_sign ).

content_commitment 

Type :: bool

This purpose is set to true when the subject public key is used for verifying digital signatures, other than signatures on certificates ( key_cert_sign ) and CRLs ( crl_sign ). It is used to provide a non-repudiation service that protects against the signing entity falsely denying some action. In the case of later conflict, a reliable third party may determine the authenticity of the signed data. This was called non_repudiation in older revisions of the X.509 specification.

key_encipherment 

Type :: bool

This purpose is set to true when the subject public key is used for enciphering private or secret keys.

data_encipherment 

Type :: bool

This purpose is set to true when the subject public key is used for directly enciphering raw user data without the use of an intermediate symmetric cipher.

key_agreement 

Type :: bool

This purpose is set to true when the subject public key is used for key agreement. For example, when a Diffie-Hellman key is to be used for key management, then this purpose is set to true.

key_cert_sign 

Type :: bool

This purpose is set to true when the subject public key is used for verifying signatures on public key certificates. If this purpose is set to true then ca must be true in the BasicConstraints extension.

crl_sign 

Type :: bool

This purpose is set to true when the subject public key is used for verifying signatures on certificate revocation lists.

encipher_only 

Type :: bool

When this purposes is set to true and the key_agreement purpose is also set, the subject public key may be used only for enciphering data while performing key agreement.

Raises :: ValueError – This is raised if accessed when key_agreement is false.

decipher_only 

Type :: bool

When this purposes is set to true and the key_agreement purpose is also set, the subject public key may be used only for deciphering data while performing key agreement.

Raises :: ValueError – This is raised if accessed when key_agreement is false.

class cryptography.x509. BasicConstraints ( ca , path_length ) [source] 

Added in version 0.9.

Basic constraints is an X.509 extension type that defines whether a given certificate is allowed to sign additional certificates and what path length restrictions may exist.

oid 

Added in version 1.0.

Type :: ObjectIdentifier

Returns BASIC_CONSTRAINTS .

ca 

Type :: bool

Whether the certificate can sign certificates.

path_length 

Type :: int or None

The maximum path length for certificates subordinate to this certificate. This attribute only has meaning if ca is true. If ca is true then a path length of None means there’s no restriction on the number of subordinate CAs in the certificate chain. If it is zero or greater then it defines the maximum length for a subordinate CA’s certificate chain. For example, a path_length of 1 means the certificate can sign a subordinate CA, but the subordinate CA is not allowed to create subordinates with ca set to true.

class cryptography.x509. ExtendedKeyUsage ( usages ) [source] 

Added in version 0.9.

This extension indicates one or more purposes for which the certified public key may be used, in addition to or in place of the basic purposes indicated in the key usage extension. The object is iterable to obtain the list of ExtendedKeyUsageOID OIDs present.

Parameters :: usages ( list ) – A list of ExtendedKeyUsageOID OIDs.

oid 

Added in version 1.0.

Type :: ObjectIdentifier

Returns EXTENDED_KEY_USAGE .

class cryptography.x509. OCSPNoCheck [source] 

Added in version 1.0.

This presence of this extension indicates that an OCSP client can trust a responder for the lifetime of the responder’s certificate. CAs issuing such a certificate should realize that a compromise of the responder’s key is as serious as the compromise of a CA key used to sign CRLs, at least for the validity period of this certificate. CA’s may choose to issue this type of certificate with a very short lifetime and renew it frequently. This extension is only relevant when the certificate is an authorized OCSP responder.

oid 

Added in version 1.0.

Type :: ObjectIdentifier

Returns OCSP_NO_CHECK .

class cryptography.x509. TLSFeature ( features ) [source] 

Added in version 2.1.

The TLS Feature extension is defined in RFC 7633 and is used in certificates for OCSP Must-Staple. The object is iterable to get every element.

Parameters :: features ( list ) – A list of features to enable from the TLSFeatureType enum. At this time only status_request or status_request_v2 are allowed.

oid 

Type :: ObjectIdentifier

Returns TLS_FEATURE .

class cryptography.x509. TLSFeatureType [source] 

Added in version 2.1.

An enumeration of TLS Feature types.

status_request : This feature type is defined in RFC 6066 and, when embedded in an X.509 certificate, signals to the client that it should require a stapled OCSP response in the TLS handshake. Commonly known as OCSP Must-Staple in certificates.

status_request_v2 : This feature type is defined in RFC 6961 . This value is not commonly used and if you want to enable OCSP Must-Staple you should use status_request .

class cryptography.x509. NameConstraints ( permitted_subtrees , excluded_subtrees ) [source] 

Added in version 1.0.

The name constraints extension, which only has meaning in a CA certificate, defines a name space within which all subject names in certificates issued beneath the CA certificate must (or must not) be in. For specific details on the way this extension should be processed see RFC 5280 .

oid 

Added in version 1.0.

Type :: ObjectIdentifier

Returns NAME_CONSTRAINTS .

permitted_subtrees 

Type :: list of GeneralName objects or None

The set of permitted name patterns. If a name matches this and an element in excluded_subtrees it is invalid. At least one of permitted_subtrees and excluded_subtrees will be non-None.

excluded_subtrees 

Type :: list of GeneralName objects or None

Any name matching a restriction in the excluded_subtrees field is invalid regardless of information appearing in the permitted_subtrees . At least one of permitted_subtrees and excluded_subtrees will be non-None.

class cryptography.x509. AuthorityKeyIdentifier ( key_identifier , authority_cert_issuer , authority_cert_serial_number ) [source] 

Added in version 0.9.

The authority key identifier extension provides a means of identifying the public key corresponding to the private key used to sign a certificate. This extension is typically used to assist in determining the appropriate certificate chain. For more information about generation and use of this extension see RFC 5280 section 4.2.1.1 .

oid 

Added in version 1.0.

Type :: ObjectIdentifier

Returns AUTHORITY_KEY_IDENTIFIER .

key_identifier 

Type :: bytes

A value derived from the public key used to verify the certificate’s signature.

authority_cert_issuer 

Type :: A list of GeneralName instances or None

The GeneralName (one or multiple) of the issuer’s issuer.

authority_cert_serial_number 

Type :: int or None

The serial number of the issuer’s issuer.

classmethod from_issuer_public_key ( public_key ) [source] 

Added in version 1.0.

Note

This method should be used if the issuer certificate does not contain a SubjectKeyIdentifier . Otherwise, use from_issuer_subject_key_identifier() .

Creates a new AuthorityKeyIdentifier instance using the public key provided to generate the appropriate digest. This should be the issuer’s public key . The resulting object will contain key_identifier , but authority_cert_issuer and authority_cert_serial_number will be None. The generated key_identifier is the SHA1 hash of the subjectPublicKey ASN.1 bit string. This is the first recommendation in RFC 5280 section 4.2.1.2.

Parameters :: public_key – One of CertificateIssuerPublicKeyTypes .

>>> from cryptography import x509
>>> issuer_cert = x509.load_pem_x509_certificate(pem_data)
>>> x509.AuthorityKeyIdentifier.from_issuer_public_key(issuer_cert.public_key())
<AuthorityKeyIdentifier(key_identifier=b'X\x01\x84$\x1b\xbc+R\x94J=\xa5\x10r\x14Q\xf5\xaf:\xc9', authority_cert_issuer=None, authority_cert_serial_number=None)>

classmethod from_issuer_subject_key_identifier ( ski ) [source] 

Added in version 1.3.

Note

This method should be used if the issuer certificate contains a SubjectKeyIdentifier . Otherwise, use from_issuer_public_key() .

Creates a new AuthorityKeyIdentifier instance using the SubjectKeyIdentifier from the issuer certificate. The resulting object will contain key_identifier , but authority_cert_issuer and authority_cert_serial_number will be None.

Parameters :: ski – The SubjectKeyIdentifier from the issuer certificate.

>>> from cryptography import x509
>>> issuer_cert = x509.load_pem_x509_certificate(pem_data)
>>> ski_ext = issuer_cert.extensions.get_extension_for_class(x509.SubjectKeyIdentifier)
>>> x509.AuthorityKeyIdentifier.from_issuer_subject_key_identifier(ski_ext.value)
<AuthorityKeyIdentifier(key_identifier=b'X\x01\x84$\x1b\xbc+R\x94J=\xa5\x10r\x14Q\xf5\xaf:\xc9', authority_cert_issuer=None, authority_cert_serial_number=None)>

class cryptography.x509. SubjectKeyIdentifier ( digest ) [source] 

Added in version 0.9.

The subject key identifier extension provides a means of identifying certificates that contain a particular public key.

oid 

Added in version 1.0.

Type :: ObjectIdentifier

Returns SUBJECT_KEY_IDENTIFIER .

key_identifier 

Added in version 35.0.0.

Type :: bytes

The binary value of the identifier.

digest 

Type :: bytes

The binary value of the identifier. An alias of key_identifier .

classmethod from_public_key ( public_key ) [source] 

Added in version 1.0.

Creates a new SubjectKeyIdentifier instance using the public key provided to generate the appropriate digest. This should be the public key that is in the certificate. The generated digest is the SHA1 hash of the subjectPublicKey ASN.1 bit string. This is the first recommendation in RFC 5280 section 4.2.1.2.

Parameters :: public_key – One of CertificatePublicKeyTypes .

>>> from cryptography import x509
>>> csr = x509.load_pem_x509_csr(pem_req_data)
>>> x509.SubjectKeyIdentifier.from_public_key(csr.public_key())
<SubjectKeyIdentifier(digest=b'\x8c"\x98\xe2\xb5\xbf]\xe8*2\xf8\xd2\'?\x00\xd2\xc7#\xe4c')>

class cryptography.x509. SubjectAlternativeName ( general_names ) [source] 

Added in version 0.9.

Subject alternative name is an X.509 extension that provides a list of general name instances that provide a set of identities for which the certificate is valid. The object is iterable to get every element.

Parameters :: general_names ( list ) – A list of GeneralName instances.

oid 

Added in version 1.0.

Type :: ObjectIdentifier

Returns SUBJECT_ALTERNATIVE_NAME .

get_values_for_type ( type ) [source] 

Parameters :: type – A GeneralName instance. This is one of the general name classes .
Returns :: A list of values extracted from the matched general names. The type of the returned values depends on the GeneralName .

>>> from cryptography import x509
>>> from cryptography.hazmat.primitives import hashes
>>> cert = x509.load_pem_x509_certificate(cryptography_cert_pem)
>>> # Get the subjectAltName extension from the certificate
>>> ext = cert.extensions.get_extension_for_oid(ExtensionOID.SUBJECT_ALTERNATIVE_NAME)
>>> # Get the dNSName entries from the SAN extension
>>> ext.value.get_values_for_type(x509.DNSName)
['www.cryptography.io', 'cryptography.io']

class cryptography.x509. IssuerAlternativeName ( general_names ) [source] 

Added in version 1.0.

Issuer alternative name is an X.509 extension that provides a list of general name instances that provide a set of identities for the certificate issuer. The object is iterable to get every element.

Parameters :: general_names ( list ) – A list of GeneralName instances.

oid 

Added in version 1.0.

Type :: ObjectIdentifier

Returns ISSUER_ALTERNATIVE_NAME .

get_values_for_type ( type ) [source] 

Parameters :: type – A GeneralName instance. This is one of the general name classes .
Returns :: A list of values extracted from the matched general names.

class cryptography.x509. PrecertificateSignedCertificateTimestamps ( scts ) [source] 

Added in version 2.0.

This extension contains SignedCertificateTimestamp instances which were issued for the pre-certificate corresponding to this certificate. These can be used to verify that the certificate is included in a public Certificate Transparency log.

It is an iterable containing one or more SignedCertificateTimestamp objects.

Parameters :: scts ( list ) – A list of SignedCertificateTimestamp objects.

oid 

Type :: ObjectIdentifier

Returns PRECERT_SIGNED_CERTIFICATE_TIMESTAMPS .

class cryptography.x509. PrecertPoison [source] 

Added in version 2.4.

This extension indicates that the certificate should not be treated as a certificate for the purposes of validation, but is instead for submission to a certificate transparency log in order to obtain SCTs which will be embedded in a PrecertificateSignedCertificateTimestamps extension on the final certificate.

oid 

Type :: ObjectIdentifier

Returns PRECERT_POISON .

class cryptography.x509. SignedCertificateTimestamps ( scts ) [source] 

Added in version 3.0.

This extension contains SignedCertificateTimestamp instances. These can be used to verify that the certificate is included in a public Certificate Transparency log. This extension is only found in OCSP responses. For SCTs in an X.509 certificate see PrecertificateSignedCertificateTimestamps .

It is an iterable containing one or more SignedCertificateTimestamp objects.

Parameters :: scts ( list ) – A list of SignedCertificateTimestamp objects.

oid 

Type :: ObjectIdentifier

Returns SIGNED_CERTIFICATE_TIMESTAMPS .

class cryptography.x509. DeltaCRLIndicator ( crl_number ) [source] 

Added in version 2.1.

The delta CRL indicator is a CRL extension that identifies a CRL as being a delta CRL. Delta CRLs contain updates to revocation information previously distributed, rather than all the information that would appear in a complete CRL.

Parameters :: crl_number ( int ) – The CRL number of the complete CRL that the delta CRL is updating.

oid 

Type :: ObjectIdentifier

Returns DELTA_CRL_INDICATOR .

crl_number 

Type :: int

class cryptography.x509. AuthorityInformationAccess ( descriptions ) [source] 

Added in version 0.9.

The authority information access extension indicates how to access information and services for the issuer of the certificate in which the extension appears. Information and services may include online validation services (such as OCSP) and issuer data. It is an iterable, containing one or more AccessDescription instances.

Parameters :: descriptions ( list ) – A list of AccessDescription objects.

oid 

Added in version 1.0.

Type :: ObjectIdentifier

Returns AUTHORITY_INFORMATION_ACCESS .

class cryptography.x509. SubjectInformationAccess ( descriptions ) [source] 

Added in version 3.0.

The subject information access extension indicates how to access information and services for the subject of the certificate in which the extension appears. When the subject is a CA, information and services may include certificate validation services and CA policy data. When the subject is an end entity, the information describes the type of services offered and how to access them. It is an iterable, containing one or more AccessDescription instances.

Parameters :: descriptions ( list ) – A list of AccessDescription objects.

oid 

Type :: ObjectIdentifier

Returns SUBJECT_INFORMATION_ACCESS .

class cryptography.x509. AccessDescription ( access_method , access_location ) [source] 

Added in version 0.9.

access_method 

Type :: ObjectIdentifier

The access method defines what the access_location means. It must be OCSP or CA_ISSUERS when used with AuthorityInformationAccess or CA_REPOSITORY when used with SubjectInformationAccess .

If it is OCSP the access location will be where to obtain OCSP information for the certificate. If it is CA_ISSUERS the access location will provide additional information about the issuing certificate. Finally, if it is CA_REPOSITORY the access location will be the location of the CA’s repository.

access_location 

Type :: GeneralName

Where to access the information defined by the access method.

class cryptography.x509. FreshestCRL ( distribution_points ) [source] 

Added in version 2.1.

The freshest CRL extension (also known as Delta CRL Distribution Point) identifies how delta CRL information is obtained. It is an iterable, containing one or more DistributionPoint instances.

Parameters :: distribution_points ( list ) – A list of DistributionPoint instances.

oid 

Type :: ObjectIdentifier

Returns FRESHEST_CRL .

class cryptography.x509. CRLDistributionPoints ( distribution_points ) [source] 

Added in version 0.9.

The CRL distribution points extension identifies how CRL information is obtained. It is an iterable, containing one or more DistributionPoint instances.

Parameters :: distribution_points ( list ) – A list of DistributionPoint instances.

oid 

Added in version 1.0.

Type :: ObjectIdentifier

Returns CRL_DISTRIBUTION_POINTS .

class cryptography.x509. DistributionPoint ( full_name , relative_name , reasons , crl_issuer ) [source] 

Added in version 0.9.

full_name 

Type :: list of GeneralName instances or None

This field describes methods to retrieve the CRL. At most one of full_name or relative_name will be non-None.

relative_name 

Type :: RelativeDistinguishedName or None

This field describes methods to retrieve the CRL relative to the CRL issuer. At most one of full_name or relative_name will be non-None.

Changed in version 1.6: Changed from Name to RelativeDistinguishedName .

crl_issuer 

Type :: list of GeneralName instances or None

Information about the issuer of the CRL.

reasons 

Type :: frozenset of ReasonFlags or None

The reasons a given distribution point may be used for when performing revocation checks.

class cryptography.x509. ReasonFlags [source] 

Added in version 0.9.

An enumeration for CRL reasons.

unspecified : It is unspecified why the certificate was revoked. This reason cannot be used as a reason flag in a DistributionPoint .

key_compromise : This reason indicates that the private key was compromised.

ca_compromise : This reason indicates that the CA issuing the certificate was compromised.

affiliation_changed : This reason indicates that the subject’s name or other information has changed.

superseded : This reason indicates that a certificate has been superseded.

cessation_of_operation : This reason indicates that the certificate is no longer required.

certificate_hold : This reason indicates that the certificate is on hold.

privilege_withdrawn : This reason indicates that the privilege granted by this certificate have been withdrawn.

aa_compromise : When an attribute authority has been compromised.

remove_from_crl : This reason indicates that the certificate was on hold and should be removed from the CRL. This reason cannot be used as a reason flag in a DistributionPoint .

class cryptography.x509. InhibitAnyPolicy ( skip_certs ) [source] 

Added in version 1.0.

The inhibit anyPolicy extension indicates that the special OID ANY_POLICY , is not considered an explicit match for other CertificatePolicies except when it appears in an intermediate self-issued CA certificate. The value indicates the number of additional non-self-issued certificates that may appear in the path before ANY_POLICY is no longer permitted. For example, a value of one indicates that ANY_POLICY may be processed in certificates issued by the subject of this certificate, but not in additional certificates in the path.

oid 

Added in version 1.0.

Type :: ObjectIdentifier

Returns INHIBIT_ANY_POLICY .

skip_certs 

Type :: int

class cryptography.x509. PolicyConstraints [source] 

Added in version 1.3.

The policy constraints extension is used to inhibit policy mapping or require that each certificate in a chain contain an acceptable policy identifier. For more information about the use of this extension see RFC 5280 .

oid 

Type :: ObjectIdentifier

Returns POLICY_CONSTRAINTS .

require_explicit_policy 

Type :: int or None

If this field is not None, the value indicates the number of additional certificates that may appear in the chain before an explicit policy is required for the entire path. When an explicit policy is required, it is necessary for all certificates in the chain to contain an acceptable policy identifier in the certificate policies extension. An acceptable policy identifier is the identifier of a policy required by the user of the certification path or the identifier of a policy that has been declared equivalent through policy mapping.

inhibit_policy_mapping 

Type :: int or None

If this field is not None, the value indicates the number of additional certificates that may appear in the chain before policy mapping is no longer permitted. For example, a value of one indicates that policy mapping may be processed in certificates issued by the subject of this certificate, but not in additional certificates in the chain.

class cryptography.x509. CRLNumber ( crl_number ) [source] 

Added in version 1.2.

The CRL number is a CRL extension that conveys a monotonically increasing sequence number for a given CRL scope and CRL issuer. This extension allows users to easily determine when a particular CRL supersedes another CRL. RFC 5280 requires that this extension be present in conforming CRLs.

oid 

Type :: ObjectIdentifier

Returns CRL_NUMBER .

crl_number 

Type :: int

class cryptography.x509. IssuingDistributionPoint ( full_name , relative_name , only_contains_user_certs , only_contains_ca_certs , only_some_reasons , indirect_crl , only_contains_attribute_certs ) [source] 

Added in version 2.5.

Issuing distribution point is a CRL extension that identifies the CRL distribution point and scope for a particular CRL. It indicates whether the CRL covers revocation for end entity certificates only, CA certificates only, attribute certificates only, or a limited set of reason codes. For specific details on the way this extension should be processed see RFC 5280 .

oid 

Type :: ObjectIdentifier

Returns ISSUING_DISTRIBUTION_POINT .

only_contains_user_certs 

Type :: bool

Set to True if the CRL this extension is embedded within only contains information about user certificates.

only_contains_ca_certs 

Type :: bool

Set to True if the CRL this extension is embedded within only contains information about CA certificates.

indirect_crl 

Type :: bool

Set to True if the CRL this extension is embedded within includes certificates issued by one or more authorities other than the CRL issuer.

only_contains_attribute_certs 

Type :: bool

Set to True if the CRL this extension is embedded within only contains information about attribute certificates.

only_some_reasons 

Type :: frozenset of ReasonFlags or None

The reasons for which the issuing distribution point is valid. None indicates that it is valid for all reasons.

full_name 

Type :: list of GeneralName instances or None

This field describes methods to retrieve the CRL. At most one of full_name or relative_name will be non-None.

relative_name 

Type :: RelativeDistinguishedName or None

This field describes methods to retrieve the CRL relative to the CRL issuer. At most one of full_name or relative_name will be non-None.

class cryptography.x509. UnrecognizedExtension [source] 

Added in version 1.2.

A generic extension class used to hold the raw value of extensions that cryptography does not know how to parse. This can also be used when creating new certificates, CRLs, or OCSP requests and responses to encode extensions that cryptography does not know how to generate.

oid 

Type :: ObjectIdentifier

Returns the OID associated with this extension.

value 

Type :: bytes

Returns the DER encoded bytes payload of the extension.

class cryptography.x509. MSCertificateTemplate ( template_id , major_version , minor_version ) [source] 

Added in version 41.0.0.

The Microsoft certificate template extension is a proprietary Microsoft PKI extension that is used to provide information about the template associated with the certificate.

oid 

Type :: ObjectIdentifier

Returns MS_CERTIFICATE_TEMPLATE .

template_id 

Type :: ObjectIdentifier

major_version 

Type :: int or None

minor_version 

Type :: int or None

class cryptography.x509. CertificatePolicies ( policies ) [source] 

Added in version 0.9.

The certificate policies extension is an iterable, containing one or more PolicyInformation instances.

Parameters :: policies ( list ) – A list of PolicyInformation instances.

As an example of how CertificatePolicies might be used, if you wanted to check if a certificated contained the CAB Forum’s “domain-validated” policy, you might write code like:

def contains_domain_validated(policies):
    return any(
        policy.policy_identifier.dotted_string == "2.23.140.1.2.1"
        for policy in policies
    )

oid 

Added in version 1.0.

Type :: ObjectIdentifier

Returns CERTIFICATE_POLICIES .

Certificate Policies Classes 

These classes may be present within a CertificatePolicies instance.

class cryptography.x509. PolicyInformation ( policy_identifier , policy_qualifiers ) [source] 

Added in version 0.9.

Contains a policy identifier and an optional list of qualifiers.

policy_identifier 

Type :: ObjectIdentifier

policy_qualifiers 

Type :: list

A list consisting of str and/or UserNotice objects. If the value is str it is a pointer to the practice statement published by the certificate authority. If it is a user notice it is meant for display to the relying party when the certificate is used.

class cryptography.x509. UserNotice ( notice_reference , explicit_text ) [source] 

Added in version 0.9.

User notices are intended for display to a relying party when a certificate is used. In practice, few if any UIs expose this data and it is a rarely encoded component.

notice_reference 

Type :: NoticeReference or None

The notice reference field names an organization and identifies, by number, a particular statement prepared by that organization.

explicit_text 

This field includes an arbitrary textual statement directly in the certificate.

Type :: str

class cryptography.x509. NoticeReference ( organization , notice_numbers ) [source] 

Notice reference can name an organization and provide information about notices related to the certificate. For example, it might identify the organization name and notice number 1. Application software could have a notice file containing the current set of notices for the named organization; the application would then extract the notice text from the file and display it. In practice this is rarely seen.

Added in version 0.9.

organization 

Type :: str

notice_numbers 

Type :: list

A list of integers.

CRL Entry Extensions 

These extensions are only valid within a RevokedCertificate object.

class cryptography.x509. CertificateIssuer ( general_names ) [source] 

Added in version 1.2.

The certificate issuer is an extension that is only valid inside RevokedCertificate objects. If the indirectCRL property of the parent CRL’s IssuingDistributionPoint extension is set, then this extension identifies the certificate issuer associated with the revoked certificate. The object is iterable to get every element.

Parameters :: general_names ( list ) – A list of GeneralName instances.

oid 

Type :: ObjectIdentifier

Returns CERTIFICATE_ISSUER .

get_values_for_type ( type ) [source] 

Parameters :: type – A GeneralName instance. This is one of the general name classes .
Returns :: A list of values extracted from the matched general names. The type of the returned values depends on the GeneralName .

class cryptography.x509. CRLReason ( reason ) [source] 

Added in version 1.2.

CRL reason (also known as reasonCode ) is an extension that is only valid inside RevokedCertificate objects. It identifies a reason for the certificate revocation.

Parameters :: reason – An element from ReasonFlags .

oid 

Type :: ObjectIdentifier

Returns CRL_REASON .

reason 

Type :: An element from ReasonFlags

class cryptography.x509. InvalidityDate ( invalidity_date ) [source] 

Added in version 1.2.

Invalidity date is an extension that is only valid inside RevokedCertificate objects. It provides the date on which it is known or suspected that the private key was compromised or that the certificate otherwise became invalid. This date may be earlier than the revocation date in the CRL entry, which is the date at which the CA processed the revocation.

Parameters :: invalidity_date – The datetime.datetime when it is known or suspected that the private key was compromised.

oid 

Type :: ObjectIdentifier

Returns INVALIDITY_DATE .

invalidity_date 

Type :: datetime.datetime

OCSP Extensions 

class cryptography.x509. OCSPNonce ( nonce ) [source] 

Added in version 2.4.

OCSP nonce is an extension that is only valid inside OCSPRequest and OCSPResponse objects. The nonce cryptographically binds a request and a response to prevent replay attacks. In practice nonces are rarely used in OCSP due to the desire to precompute OCSP responses at large scale.

oid 

Type :: ObjectIdentifier

Returns NONCE .

nonce 

Type :: bytes

class cryptography.x509. OCSPAcceptableResponses ( response ) [source] 

Added in version 41.0.0.

OCSP acceptable responses is an extension that is only valid inside OCSPRequest objects. This allows an OCSP client to tell the server what types of responses it supports. In practice this is rarely used, because there is only one kind of OCSP response in wide use.

oid 

Type :: ObjectIdentifier

Returns ACCEPTABLE_RESPONSES .

nonce 

Type :: bytes

X.509 Request Attributes 

class cryptography.x509. Attributes [source] 

Added in version 36.0.0.

An Attributes instance is an ordered list of attributes. The object is iterable to get every attribute. Each returned element is an Attribute .

get_attribute_for_oid ( oid ) [source] 

Added in version 36.0.0.

Parameters :: oid – An ObjectIdentifier instance.
Returns :: The Attribute or an exception if not found.
Raises :: cryptography.x509.AttributeNotFound – If the request does not have the attribute requested.

class cryptography.x509. Attribute [source] 

Added in version 36.0.0.

An attribute associated with an X.509 request.

oid 

Type :: ObjectIdentifier

Returns the object identifier for the attribute.

value 

Type :: bytes

Returns the value of the attribute.

Object Identifiers 

X.509 elements are frequently identified by ObjectIdentifier instances. The following common OIDs are available as constants.

class cryptography.x509.oid. NameOID [source] 

These OIDs are typically seen in X.509 names.

Added in version 1.0.

COMMON_NAME : Corresponds to the dotted string "2.5.4.3" . Historically the domain name would be encoded here for server certificates. RFC 2818 deprecates this practice and names of that type should now be located in a SubjectAlternativeName extension.

COUNTRY_NAME : Corresponds to the dotted string "2.5.4.6" .

LOCALITY_NAME : Corresponds to the dotted string "2.5.4.7" .

STATE_OR_PROVINCE_NAME : Corresponds to the dotted string "2.5.4.8" .

STREET_ADDRESS 

Added in version 1.6.

Corresponds to the dotted string "2.5.4.9" .

ORGANIZATION_IDENTIFIER 

Added in version 42.0.0.

Corresponds to the dotted string "2.5.4.97" .

ORGANIZATION_NAME : Corresponds to the dotted string "2.5.4.10" .

ORGANIZATIONAL_UNIT_NAME : Corresponds to the dotted string "2.5.4.11" .

SERIAL_NUMBER : Corresponds to the dotted string "2.5.4.5" . This is distinct from the serial number of the certificate itself (which can be obtained with serial_number ).

SURNAME : Corresponds to the dotted string "2.5.4.4" .

GIVEN_NAME : Corresponds to the dotted string "2.5.4.42" .

TITLE : Corresponds to the dotted string "2.5.4.12" .

INITIALS 

Added in version 41.0.0.

Corresponds to the dotted string "2.5.4.43" .

GENERATION_QUALIFIER : Corresponds to the dotted string "2.5.4.44" .

X500_UNIQUE_IDENTIFIER 

Added in version 1.6.

Corresponds to the dotted string "2.5.4.45" .

DN_QUALIFIER : Corresponds to the dotted string "2.5.4.46" . This specifies disambiguating information to add to the relative distinguished name of an entry. See RFC 2256 .

PSEUDONYM : Corresponds to the dotted string "2.5.4.65" .

USER_ID 

Added in version 1.6.

Corresponds to the dotted string "0.9.2342.19200300.100.1.1" .

DOMAIN_COMPONENT : Corresponds to the dotted string "0.9.2342.19200300.100.1.25" . A string holding one component of a domain name. See RFC 4519 .

EMAIL_ADDRESS : Corresponds to the dotted string "1.2.840.113549.1.9.1" .

JURISDICTION_COUNTRY_NAME : Corresponds to the dotted string "1.3.6.1.4.1.311.60.2.1.3" .

JURISDICTION_LOCALITY_NAME : Corresponds to the dotted string "1.3.6.1.4.1.311.60.2.1.1" .

JURISDICTION_STATE_OR_PROVINCE_NAME : Corresponds to the dotted string "1.3.6.1.4.1.311.60.2.1.2" .

BUSINESS_CATEGORY : Corresponds to the dotted string "2.5.4.15" .

POSTAL_ADDRESS 

Added in version 1.6.

Corresponds to the dotted string "2.5.4.16" .

POSTAL_CODE 

Added in version 1.6.

Corresponds to the dotted string "2.5.4.17" .

UNSTRUCTURED_NAME 

Added in version 3.0.

Corresponds to the dotted string "1.2.840.113549.1.9.2" .

class cryptography.x509.oid. SignatureAlgorithmOID [source] 

Added in version 1.0.

RSA_WITH_MD5 : Corresponds to the dotted string "1.2.840.113549.1.1.4" . This is an MD5 digest signed by an RSA key.

RSA_WITH_SHA1 : Corresponds to the dotted string "1.2.840.113549.1.1.5" . This is a SHA1 digest signed by an RSA key.

RSA_WITH_SHA224 : Corresponds to the dotted string "1.2.840.113549.1.1.14" . This is a SHA224 digest signed by an RSA key.

RSA_WITH_SHA256 : Corresponds to the dotted string "1.2.840.113549.1.1.11" . This is a SHA256 digest signed by an RSA key.

RSA_WITH_SHA384 : Corresponds to the dotted string "1.2.840.113549.1.1.12" . This is a SHA384 digest signed by an RSA key.

RSA_WITH_SHA512 : Corresponds to the dotted string "1.2.840.113549.1.1.13" . This is a SHA512 digest signed by an RSA key.

RSA_WITH_SHA3_224 : Corresponds to the dotted string "2.16.840.1.101.3.4.3.13" . This is a SHA3-224 digest signed by an RSA key.

RSA_WITH_SHA3_256 : Corresponds to the dotted string "2.16.840.1.101.3.4.3.14" . This is a SHA3-256 digest signed by an RSA key.

RSA_WITH_SHA3_384 : Corresponds to the dotted string "2.16.840.1.101.3.4.3.15" . This is a SHA3-384 digest signed by an RSA key.

RSA_WITH_SHA3_512 : Corresponds to the dotted string "2.16.840.1.101.3.4.3.16" . This is a SHA3-512 digest signed by an RSA key.

RSASSA_PSS 

Added in version 2.3.

Corresponds to the dotted string "1.2.840.113549.1.1.10" . This is signed by an RSA key using the Probabilistic Signature Scheme (PSS) padding from RFC 4055 . The hash function and padding are defined by signature algorithm parameters.

ECDSA_WITH_SHA1 : Corresponds to the dotted string "1.2.840.10045.4.1" . This is a SHA1 digest signed by an ECDSA key.

ECDSA_WITH_SHA224 : Corresponds to the dotted string "1.2.840.10045.4.3.1" . This is a SHA224 digest signed by an ECDSA key.

ECDSA_WITH_SHA256 : Corresponds to the dotted string "1.2.840.10045.4.3.2" . This is a SHA256 digest signed by an ECDSA key.

ECDSA_WITH_SHA384 : Corresponds to the dotted string "1.2.840.10045.4.3.3" . This is a SHA384 digest signed by an ECDSA key.

ECDSA_WITH_SHA512 : Corresponds to the dotted string "1.2.840.10045.4.3.4" . This is a SHA512 digest signed by an ECDSA key.

ECDSA_WITH_SHA3_224 : Corresponds to the dotted string "2.16.840.1.101.3.4.3.9" . This is a SHA3-224 digest signed by an ECDSA key.

ECDSA_WITH_SHA3_256 : Corresponds to the dotted string "2.16.840.1.101.3.4.3.10" . This is a SHA3-256 digest signed by an ECDSA key.

ECDSA_WITH_SHA3_384 : Corresponds to the dotted string "2.16.840.1.101.3.4.3.11" . This is a SHA3-384 digest signed by an ECDSA key.

ECDSA_WITH_SHA3_512 : Corresponds to the dotted string "2.16.840.1.101.3.4.3.12" . This is a SHA3-512 digest signed by an ECDSA key.

DSA_WITH_SHA1 : Corresponds to the dotted string "1.2.840.10040.4.3" . This is a SHA1 digest signed by a DSA key.

DSA_WITH_SHA224 : Corresponds to the dotted string "2.16.840.1.101.3.4.3.1" . This is a SHA224 digest signed by a DSA key.

DSA_WITH_SHA256 : Corresponds to the dotted string "2.16.840.1.101.3.4.3.2" . This is a SHA256 digest signed by a DSA key.

DSA_WITH_SHA384 

Added in version 36.0.0.

Corresponds to the dotted string "2.16.840.1.101.3.4.3.3" . This is a SHA384 digest signed by a DSA key.

DSA_WITH_SHA512 

Added in version 36.0.0.

Corresponds to the dotted string "2.16.840.1.101.3.4.3.4" . This is a SHA512 digest signed by a DSA key.

ED25519 

Added in version 2.8.

Corresponds to the dotted string "1.3.101.112" . This is a signature using an ed25519 key.

ED448 

Added in version 2.8.

Corresponds to the dotted string "1.3.101.113" . This is a signature using an ed448 key.

class cryptography.x509.oid. ExtendedKeyUsageOID [source] 

Added in version 1.0.

SERVER_AUTH : Corresponds to the dotted string "1.3.6.1.5.5.7.3.1" . This is used to denote that a certificate may be used for TLS web server authentication.

CLIENT_AUTH : Corresponds to the dotted string "1.3.6.1.5.5.7.3.2" . This is used to denote that a certificate may be used for TLS web client authentication.

CODE_SIGNING : Corresponds to the dotted string "1.3.6.1.5.5.7.3.3" . This is used to denote that a certificate may be used for code signing.

EMAIL_PROTECTION : Corresponds to the dotted string "1.3.6.1.5.5.7.3.4" . This is used to denote that a certificate may be used for email protection.

TIME_STAMPING : Corresponds to the dotted string "1.3.6.1.5.5.7.3.8" . This is used to denote that a certificate may be used for time stamping.

OCSP_SIGNING : Corresponds to the dotted string "1.3.6.1.5.5.7.3.9" . This is used to denote that a certificate may be used for signing OCSP responses.

ANY_EXTENDED_KEY_USAGE 

Added in version 2.0.

Corresponds to the dotted string "2.5.29.37.0" . This is used to denote that a certificate may be used for _any_ purposes. However, RFC 5280 additionally notes that applications that require the presence of a particular purpose _MAY_ reject certificates that include the anyExtendedKeyUsage OID but not the particular OID expected for the application. Therefore, the presence of this OID does not mean a given application will accept the certificate for all purposes.

SMARTCARD_LOGON 

Added in version 35.0.0.

Corresponds to the dotted string "1.3.6.1.4.1.311.20.2.2" . This is used to denote that a certificate may be used for PKINIT access on Windows.

KERBEROS_PKINIT_KDC 

Added in version 35.0.0.

Corresponds to the dotted string "1.3.6.1.5.2.3.5" . This is used to denote that a certificate may be used as a Kerberos domain controller certificate authorizing PKINIT access. For more information see RFC 4556 .

IPSEC_IKE 

Added in version 37.0.0.

Corresponds to the dotted string "1.3.6.1.5.5.7.3.17" . This is used to denote that a certificate may be assigned to an IPSEC SA, and can be used by the assignee to initiate an IPSec Internet Key Exchange. For more information see RFC 4945 .

CERTIFICATE_TRANSPARENCY 

Added in version 38.0.0.

Corresponds to the dotted string "1.3.6.1.4.1.11129.2.4.4" . This is used to denote that a certificate may be used as a pre-certificate signing certificate for Certificate Transparency log operation purposes. For more information see RFC 6962 .

class cryptography.x509.oid. AuthorityInformationAccessOID [source] 

Added in version 1.0.

OCSP : Corresponds to the dotted string "1.3.6.1.5.5.7.48.1" . Used as the identifier for OCSP data in AccessDescription objects.

CA_ISSUERS : Corresponds to the dotted string "1.3.6.1.5.5.7.48.2" . Used as the identifier for CA issuer data in AccessDescription objects.

class cryptography.x509.oid. SubjectInformationAccessOID [source] 

Added in version 3.0.

CA_REPOSITORY : Corresponds to the dotted string "1.3.6.1.5.5.7.48.5" . Used as the identifier for CA repository data in AccessDescription objects.

class cryptography.x509.oid. CertificatePoliciesOID [source] 

Added in version 1.0.

CPS_QUALIFIER : Corresponds to the dotted string "1.3.6.1.5.5.7.2.1" .

CPS_USER_NOTICE : Corresponds to the dotted string "1.3.6.1.5.5.7.2.2" .

ANY_POLICY : Corresponds to the dotted string "2.5.29.32.0" .

class cryptography.x509.oid. ExtensionOID [source] 

Added in version 1.0.

BASIC_CONSTRAINTS : Corresponds to the dotted string "2.5.29.19" . The identifier for the BasicConstraints extension type.

KEY_USAGE : Corresponds to the dotted string "2.5.29.15" . The identifier for the KeyUsage extension type.

SUBJECT_ALTERNATIVE_NAME : Corresponds to the dotted string "2.5.29.17" . The identifier for the SubjectAlternativeName extension type.

ISSUER_ALTERNATIVE_NAME : Corresponds to the dotted string "2.5.29.18" . The identifier for the IssuerAlternativeName extension type.

SUBJECT_KEY_IDENTIFIER : Corresponds to the dotted string "2.5.29.14" . The identifier for the SubjectKeyIdentifier extension type.

NAME_CONSTRAINTS : Corresponds to the dotted string "2.5.29.30" . The identifier for the NameConstraints extension type.

CRL_DISTRIBUTION_POINTS : Corresponds to the dotted string "2.5.29.31" . The identifier for the CRLDistributionPoints extension type.

CERTIFICATE_POLICIES : Corresponds to the dotted string "2.5.29.32" . The identifier for the CertificatePolicies extension type.

AUTHORITY_KEY_IDENTIFIER : Corresponds to the dotted string "2.5.29.35" . The identifier for the AuthorityKeyIdentifier extension type.

EXTENDED_KEY_USAGE : Corresponds to the dotted string "2.5.29.37" . The identifier for the ExtendedKeyUsage extension type.

AUTHORITY_INFORMATION_ACCESS : Corresponds to the dotted string "1.3.6.1.5.5.7.1.1" . The identifier for the AuthorityInformationAccess extension type.

SUBJECT_INFORMATION_ACCESS 

Added in version 3.0.

Corresponds to the dotted string "1.3.6.1.5.5.7.1.11" . The identifier for the SubjectInformationAccess extension type.

INHIBIT_ANY_POLICY : Corresponds to the dotted string "2.5.29.54" . The identifier for the InhibitAnyPolicy extension type.

OCSP_NO_CHECK : Corresponds to the dotted string "1.3.6.1.5.5.7.48.1.5" . The identifier for the OCSPNoCheck extension type.

TLS_FEATURE : Corresponds to the dotted string "1.3.6.1.5.5.7.1.24" . The identifier for the TLSFeature extension type.

CRL_NUMBER : Corresponds to the dotted string "2.5.29.20" . The identifier for the CRLNumber extension type. This extension only has meaning for certificate revocation lists.

DELTA_CRL_INDICATOR 

Added in version 2.1.

Corresponds to the dotted string "2.5.29.27" . The identifier for the DeltaCRLIndicator extension type. This extension only has meaning for certificate revocation lists.

PRECERT_SIGNED_CERTIFICATE_TIMESTAMPS 

Added in version 1.9.

Corresponds to the dotted string "1.3.6.1.4.1.11129.2.4.2" .

PRECERT_POISON 

Added in version 2.4.

Corresponds to the dotted string "1.3.6.1.4.1.11129.2.4.3" .

SIGNED_CERTIFICATE_TIMESTAMPS 

Added in version 3.0.

Corresponds to the dotted string "1.3.6.1.4.1.11129.2.4.5" .

POLICY_CONSTRAINTS : Corresponds to the dotted string "2.5.29.36" . The identifier for the PolicyConstraints extension type.

FRESHEST_CRL : Corresponds to the dotted string "2.5.29.46" . The identifier for the FreshestCRL extension type.

ISSUING_DISTRIBUTION_POINT 

Added in version 2.4.

Corresponds to the dotted string "2.5.29.28" .

POLICY_MAPPINGS : Corresponds to the dotted string "2.5.29.33" .

SUBJECT_DIRECTORY_ATTRIBUTES : Corresponds to the dotted string "2.5.29.9" .

MS_CERTIFICATE_TEMPLATE 

Added in version 41.0.0.

Corresponds to the dotted string "1.3.6.1.4.1.311.21.7" .

class cryptography.x509.oid. CRLEntryExtensionOID [source] 

Added in version 1.2.

CERTIFICATE_ISSUER : Corresponds to the dotted string "2.5.29.29" .

CRL_REASON : Corresponds to the dotted string "2.5.29.21" .

INVALIDITY_DATE : Corresponds to the dotted string "2.5.29.24" .

class cryptography.x509.oid. OCSPExtensionOID [source] 

Added in version 2.4.

NONCE : Corresponds to the dotted string "1.3.6.1.5.5.7.48.1.2" .

ACCEPTABLE_RESPONSES 

Added in version 41.0.0.

Corresponds to the dotted string "1.3.6.1.5.5.7.48.1.4" .

class cryptography.x509.oid. AttributeOID [source] 

Added in version 3.0.

CHALLENGE_PASSWORD : Corresponds to the dotted string "1.2.840.113549.1.9.7" .

UNSTRUCTURED_NAME : Corresponds to the dotted string "1.2.840.113549.1.9.2" .

Helper Functions 

cryptography.x509. random_serial_number ( ) [source] 

Added in version 1.6.

Generates a random serial number suitable for use when constructing certificates.

Exceptions 

class cryptography.x509. InvalidVersion [source] 

This is raised when an X.509 certificate has an invalid version number.

parsed_version 

Type :: int

Returns the raw version that was parsed from the certificate.

class cryptography.x509. DuplicateExtension [source] 

This is raised when more than one X.509 extension of the same type is found within a certificate.

oid 

Type :: ObjectIdentifier

Returns the OID.

class cryptography.x509. ExtensionNotFound [source] 

This is raised when calling Extensions.get_extension_for_oid() with an extension OID that is not present in the certificate.

oid 

Type :: ObjectIdentifier

Returns the OID.

class cryptography.x509. AttributeNotFound [source] 

This is raised when calling Attributes.get_attribute_for_oid() with an attribute OID that is not present in the request.

oid 

Type :: ObjectIdentifier

Returns the OID.

class cryptography.x509. UnsupportedGeneralNameType [source] 

This is raised when a certificate contains an unsupported general name type in an extension.

type 

Type :: int

The integer value of the unsupported type. The complete list of types can be found in RFC 5280 section 4.2.1.6 .

Read the Docs v: 42.0.7

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