diff --git a/src/cryptography/x509/__init__.py b/src/cryptography/x509/__init__.py
index 04a94a3..9cc7842 100644
--- a/src/cryptography/x509/__init__.py
+++ b/src/cryptography/x509/__init__.py
@@ -25,29 +25,55 @@
 )
 from cryptography.x509.name import Name, NameAttribute
 from cryptography.x509.oid import (
-    OID_ANY_POLICY, OID_AUTHORITY_INFORMATION_ACCESS,
-    OID_AUTHORITY_KEY_IDENTIFIER, OID_BASIC_CONSTRAINTS, OID_CA_ISSUERS,
-    OID_CERTIFICATE_ISSUER, OID_CERTIFICATE_POLICIES, OID_CLIENT_AUTH,
+    ExtensionOID, OID_ANY_POLICY,
+    OID_CA_ISSUERS, OID_CERTIFICATE_ISSUER, OID_CLIENT_AUTH,
     OID_CODE_SIGNING, OID_COMMON_NAME, OID_COUNTRY_NAME, OID_CPS_QUALIFIER,
-    OID_CPS_USER_NOTICE, OID_CRL_DISTRIBUTION_POINTS, OID_CRL_REASON,
-    OID_DN_QUALIFIER, OID_DOMAIN_COMPONENT, OID_DSA_WITH_SHA1,
-    OID_DSA_WITH_SHA224, OID_DSA_WITH_SHA256, OID_ECDSA_WITH_SHA1,
-    OID_ECDSA_WITH_SHA224, OID_ECDSA_WITH_SHA256, OID_ECDSA_WITH_SHA384,
-    OID_ECDSA_WITH_SHA512, OID_EMAIL_ADDRESS, OID_EMAIL_PROTECTION,
-    OID_EXTENDED_KEY_USAGE, OID_FRESHEST_CRL, OID_GENERATION_QUALIFIER,
-    OID_GIVEN_NAME, OID_INHIBIT_ANY_POLICY, OID_INVALIDITY_DATE,
-    OID_ISSUER_ALTERNATIVE_NAME, OID_KEY_USAGE, OID_LOCALITY_NAME,
-    OID_NAME_CONSTRAINTS, OID_OCSP, OID_OCSP_NO_CHECK, OID_OCSP_SIGNING,
+    OID_CPS_USER_NOTICE, OID_CRL_REASON, OID_DN_QUALIFIER,
+    OID_DOMAIN_COMPONENT, OID_EMAIL_ADDRESS, OID_EMAIL_PROTECTION,
+    OID_GENERATION_QUALIFIER, OID_GIVEN_NAME, OID_INVALIDITY_DATE,
+    OID_LOCALITY_NAME, OID_OCSP, OID_OCSP_SIGNING,
     OID_ORGANIZATIONAL_UNIT_NAME, OID_ORGANIZATION_NAME,
-    OID_POLICY_CONSTRAINTS, OID_POLICY_MAPPINGS, OID_PSEUDONYM,
-    OID_RSA_WITH_MD5, OID_RSA_WITH_SHA1, OID_RSA_WITH_SHA224,
-    OID_RSA_WITH_SHA256, OID_RSA_WITH_SHA384, OID_RSA_WITH_SHA512,
-    OID_SERIAL_NUMBER, OID_SERVER_AUTH, OID_STATE_OR_PROVINCE_NAME,
-    OID_SUBJECT_ALTERNATIVE_NAME, OID_SUBJECT_DIRECTORY_ATTRIBUTES,
-    OID_SUBJECT_INFORMATION_ACCESS, OID_SUBJECT_KEY_IDENTIFIER, OID_SURNAME,
-    OID_TIME_STAMPING, OID_TITLE, _SIG_OIDS_TO_HASH
+    OID_PSEUDONYM, OID_SERIAL_NUMBER, OID_SERVER_AUTH,
+    OID_STATE_OR_PROVINCE_NAME, OID_SURNAME, OID_TIME_STAMPING, OID_TITLE,
+    SignatureAlgorithmOID, _SIG_OIDS_TO_HASH
 )
 
+
+OID_AUTHORITY_INFORMATION_ACCESS = ExtensionOID.AUTHORITY_INFORMATION_ACCESS
+OID_AUTHORITY_KEY_IDENTIFIER = ExtensionOID.AUTHORITY_KEY_IDENTIFIER
+OID_BASIC_CONSTRAINTS = ExtensionOID.BASIC_CONSTRAINTS
+OID_CERTIFICATE_POLICIES = ExtensionOID.CERTIFICATE_POLICIES
+OID_CRL_DISTRIBUTION_POINTS = ExtensionOID.CRL_DISTRIBUTION_POINTS
+OID_EXTENDED_KEY_USAGE = ExtensionOID.EXTENDED_KEY_USAGE
+OID_FRESHEST_CRL = ExtensionOID.FRESHEST_CRL
+OID_INHIBIT_ANY_POLICY = ExtensionOID.INHIBIT_ANY_POLICY
+OID_ISSUER_ALTERNATIVE_NAME = ExtensionOID.ISSUER_ALTERNATIVE_NAME
+OID_KEY_USAGE = ExtensionOID.KEY_USAGE
+OID_NAME_CONSTRAINTS = ExtensionOID.NAME_CONSTRAINTS
+OID_OCSP_NO_CHECK = ExtensionOID.OCSP_NO_CHECK
+OID_POLICY_CONSTRAINTS = ExtensionOID.POLICY_CONSTRAINTS
+OID_POLICY_MAPPINGS = ExtensionOID.POLICY_MAPPINGS
+OID_SUBJECT_ALTERNATIVE_NAME = ExtensionOID.SUBJECT_ALTERNATIVE_NAME
+OID_SUBJECT_DIRECTORY_ATTRIBUTES = ExtensionOID.SUBJECT_DIRECTORY_ATTRIBUTES
+OID_SUBJECT_INFORMATION_ACCESS = ExtensionOID.SUBJECT_INFORMATION_ACCESS
+OID_SUBJECT_KEY_IDENTIFIER = ExtensionOID.SUBJECT_KEY_IDENTIFIER
+
+OID_DSA_WITH_SHA1 = SignatureAlgorithmOID.DSA_WITH_SHA1
+OID_DSA_WITH_SHA224 = SignatureAlgorithmOID.DSA_WITH_SHA224
+OID_DSA_WITH_SHA256 = SignatureAlgorithmOID.DSA_WITH_SHA256
+OID_ECDSA_WITH_SHA1 = SignatureAlgorithmOID.ECDSA_WITH_SHA1
+OID_ECDSA_WITH_SHA224 = SignatureAlgorithmOID.ECDSA_WITH_SHA224
+OID_ECDSA_WITH_SHA256 = SignatureAlgorithmOID.ECDSA_WITH_SHA256
+OID_ECDSA_WITH_SHA384 = SignatureAlgorithmOID.ECDSA_WITH_SHA384
+OID_ECDSA_WITH_SHA512 = SignatureAlgorithmOID.ECDSA_WITH_SHA512
+OID_RSA_WITH_MD5 = SignatureAlgorithmOID.RSA_WITH_MD5
+OID_RSA_WITH_SHA1 = SignatureAlgorithmOID.RSA_WITH_SHA1
+OID_RSA_WITH_SHA224 = SignatureAlgorithmOID.RSA_WITH_SHA224
+OID_RSA_WITH_SHA256 = SignatureAlgorithmOID.RSA_WITH_SHA256
+OID_RSA_WITH_SHA384 = SignatureAlgorithmOID.RSA_WITH_SHA384
+OID_RSA_WITH_SHA512 = SignatureAlgorithmOID.RSA_WITH_SHA512
+
+
 __all__ = [
     "load_pem_x509_certificate",
     "load_der_x509_certificate",
@@ -99,27 +125,9 @@
     "CertificateSigningRequestBuilder",
     "CertificateBuilder",
     "Version",
-    "OID_SUBJECT_DIRECTORY_ATTRIBUTES",
-    "OID_SUBJECT_KEY_IDENTIFIER",
-    "OID_KEY_USAGE",
-    "OID_SUBJECT_ALTERNATIVE_NAME",
-    "OID_ISSUER_ALTERNATIVE_NAME",
-    "OID_BASIC_CONSTRAINTS",
     "OID_CRL_REASON",
     "OID_INVALIDITY_DATE",
     "OID_CERTIFICATE_ISSUER",
-    "OID_NAME_CONSTRAINTS",
-    "OID_CRL_DISTRIBUTION_POINTS",
-    "OID_CERTIFICATE_POLICIES",
-    "OID_POLICY_MAPPINGS",
-    "OID_AUTHORITY_KEY_IDENTIFIER",
-    "OID_POLICY_CONSTRAINTS",
-    "OID_EXTENDED_KEY_USAGE",
-    "OID_FRESHEST_CRL",
-    "OID_INHIBIT_ANY_POLICY",
-    "OID_AUTHORITY_INFORMATION_ACCESS",
-    "OID_SUBJECT_INFORMATION_ACCESS",
-    "OID_OCSP_NO_CHECK",
     "OID_COMMON_NAME",
     "OID_COUNTRY_NAME",
     "OID_LOCALITY_NAME",
@@ -135,20 +143,6 @@
     "OID_PSEUDONYM",
     "OID_DOMAIN_COMPONENT",
     "OID_EMAIL_ADDRESS",
-    "OID_RSA_WITH_MD5",
-    "OID_RSA_WITH_SHA1",
-    "OID_RSA_WITH_SHA224",
-    "OID_RSA_WITH_SHA256",
-    "OID_RSA_WITH_SHA384",
-    "OID_RSA_WITH_SHA512",
-    "OID_ECDSA_WITH_SHA1",
-    "OID_ECDSA_WITH_SHA224",
-    "OID_ECDSA_WITH_SHA256",
-    "OID_ECDSA_WITH_SHA384",
-    "OID_ECDSA_WITH_SHA512",
-    "OID_DSA_WITH_SHA1",
-    "OID_DSA_WITH_SHA224",
-    "OID_DSA_WITH_SHA256",
     "_SIG_OIDS_TO_HASH",
     "OID_CPS_QUALIFIER",
     "OID_CPS_USER_NOTICE",
diff --git a/src/cryptography/x509/base.py b/src/cryptography/x509/base.py
index a6a8be7..8eabee8 100644
--- a/src/cryptography/x509/base.py
+++ b/src/cryptography/x509/base.py
@@ -21,13 +21,7 @@
 from cryptography.x509.general_name import GeneralName, IPAddress, OtherName
 from cryptography.x509.name import Name
 from cryptography.x509.oid import (
-    OID_AUTHORITY_INFORMATION_ACCESS,
-    OID_AUTHORITY_KEY_IDENTIFIER, OID_BASIC_CONSTRAINTS,
-    OID_CA_ISSUERS, OID_CERTIFICATE_POLICIES, OID_CRL_DISTRIBUTION_POINTS,
-    OID_EXTENDED_KEY_USAGE, OID_INHIBIT_ANY_POLICY,
-    OID_ISSUER_ALTERNATIVE_NAME, OID_KEY_USAGE, OID_NAME_CONSTRAINTS,
-    OID_OCSP, OID_OCSP_NO_CHECK, OID_SUBJECT_ALTERNATIVE_NAME,
-    OID_SUBJECT_KEY_IDENTIFIER, ObjectIdentifier
+    ExtensionOID, OID_CA_ISSUERS, OID_OCSP, ObjectIdentifier
 )
 
 
@@ -172,7 +166,7 @@
 
 @utils.register_interface(ExtensionType)
 class ExtendedKeyUsage(object):
-    oid = OID_EXTENDED_KEY_USAGE
+    oid = ExtensionOID.EXTENDED_KEY_USAGE
 
     def __init__(self, usages):
         if not all(isinstance(x, ObjectIdentifier) for x in usages):
@@ -203,12 +197,12 @@
 
 @utils.register_interface(ExtensionType)
 class OCSPNoCheck(object):
-    oid = OID_OCSP_NO_CHECK
+    oid = ExtensionOID.OCSP_NO_CHECK
 
 
 @utils.register_interface(ExtensionType)
 class BasicConstraints(object):
-    oid = OID_BASIC_CONSTRAINTS
+    oid = ExtensionOID.BASIC_CONSTRAINTS
 
     def __init__(self, ca, path_length):
         if not isinstance(ca, bool):
@@ -247,7 +241,7 @@
 
 @utils.register_interface(ExtensionType)
 class KeyUsage(object):
-    oid = OID_KEY_USAGE
+    oid = ExtensionOID.KEY_USAGE
 
     def __init__(self, digital_signature, content_commitment, key_encipherment,
                  data_encipherment, key_agreement, key_cert_sign, crl_sign,
@@ -333,7 +327,7 @@
 
 @utils.register_interface(ExtensionType)
 class AuthorityInformationAccess(object):
-    oid = OID_AUTHORITY_INFORMATION_ACCESS
+    oid = ExtensionOID.AUTHORITY_INFORMATION_ACCESS
 
     def __init__(self, descriptions):
         if not all(isinstance(x, AccessDescription) for x in descriptions):
@@ -400,7 +394,7 @@
 
 @utils.register_interface(ExtensionType)
 class CertificatePolicies(object):
-    oid = OID_CERTIFICATE_POLICIES
+    oid = ExtensionOID.CERTIFICATE_POLICIES
 
     def __init__(self, policies):
         if not all(isinstance(x, PolicyInformation) for x in policies):
@@ -540,7 +534,7 @@
 
 @utils.register_interface(ExtensionType)
 class SubjectKeyIdentifier(object):
-    oid = OID_SUBJECT_KEY_IDENTIFIER
+    oid = ExtensionOID.SUBJECT_KEY_IDENTIFIER
 
     def __init__(self, digest):
         self._digest = digest
@@ -568,7 +562,7 @@
 
 @utils.register_interface(ExtensionType)
 class NameConstraints(object):
-    oid = OID_NAME_CONSTRAINTS
+    oid = ExtensionOID.NAME_CONSTRAINTS
 
     def __init__(self, permitted_subtrees, excluded_subtrees):
         if permitted_subtrees is not None:
@@ -635,7 +629,7 @@
 
 @utils.register_interface(ExtensionType)
 class CRLDistributionPoints(object):
-    oid = OID_CRL_DISTRIBUTION_POINTS
+    oid = ExtensionOID.CRL_DISTRIBUTION_POINTS
 
     def __init__(self, distribution_points):
         if not all(
@@ -759,7 +753,7 @@
 
 @utils.register_interface(ExtensionType)
 class InhibitAnyPolicy(object):
-    oid = OID_INHIBIT_ANY_POLICY
+    oid = ExtensionOID.INHIBIT_ANY_POLICY
 
     def __init__(self, skip_certs):
         if not isinstance(skip_certs, six.integer_types):
@@ -825,7 +819,7 @@
 
 @utils.register_interface(ExtensionType)
 class SubjectAlternativeName(object):
-    oid = OID_SUBJECT_ALTERNATIVE_NAME
+    oid = ExtensionOID.SUBJECT_ALTERNATIVE_NAME
 
     def __init__(self, general_names):
         self._general_names = GeneralNames(general_names)
@@ -854,7 +848,7 @@
 
 @utils.register_interface(ExtensionType)
 class IssuerAlternativeName(object):
-    oid = OID_ISSUER_ALTERNATIVE_NAME
+    oid = ExtensionOID.ISSUER_ALTERNATIVE_NAME
 
     def __init__(self, general_names):
         self._general_names = GeneralNames(general_names)
@@ -883,7 +877,7 @@
 
 @utils.register_interface(ExtensionType)
 class AuthorityKeyIdentifier(object):
-    oid = OID_AUTHORITY_KEY_IDENTIFIER
+    oid = ExtensionOID.AUTHORITY_KEY_IDENTIFIER
 
     def __init__(self, key_identifier, authority_cert_issuer,
                  authority_cert_serial_number):
diff --git a/src/cryptography/x509/oid.py b/src/cryptography/x509/oid.py
index a3cc065..87601f8 100644
--- a/src/cryptography/x509/oid.py
+++ b/src/cryptography/x509/oid.py
@@ -33,27 +33,30 @@
     dotted_string = utils.read_only_property("_dotted_string")
 
 
-OID_SUBJECT_DIRECTORY_ATTRIBUTES = ObjectIdentifier("2.5.29.9")
-OID_SUBJECT_KEY_IDENTIFIER = ObjectIdentifier("2.5.29.14")
-OID_KEY_USAGE = ObjectIdentifier("2.5.29.15")
-OID_SUBJECT_ALTERNATIVE_NAME = ObjectIdentifier("2.5.29.17")
-OID_ISSUER_ALTERNATIVE_NAME = ObjectIdentifier("2.5.29.18")
-OID_BASIC_CONSTRAINTS = ObjectIdentifier("2.5.29.19")
+class ExtensionOID(object):
+    SUBJECT_DIRECTORY_ATTRIBUTES = ObjectIdentifier("2.5.29.9")
+    SUBJECT_KEY_IDENTIFIER = ObjectIdentifier("2.5.29.14")
+    KEY_USAGE = ObjectIdentifier("2.5.29.15")
+    SUBJECT_ALTERNATIVE_NAME = ObjectIdentifier("2.5.29.17")
+    ISSUER_ALTERNATIVE_NAME = ObjectIdentifier("2.5.29.18")
+    BASIC_CONSTRAINTS = ObjectIdentifier("2.5.29.19")
+    NAME_CONSTRAINTS = ObjectIdentifier("2.5.29.30")
+    CRL_DISTRIBUTION_POINTS = ObjectIdentifier("2.5.29.31")
+    CERTIFICATE_POLICIES = ObjectIdentifier("2.5.29.32")
+    POLICY_MAPPINGS = ObjectIdentifier("2.5.29.33")
+    AUTHORITY_KEY_IDENTIFIER = ObjectIdentifier("2.5.29.35")
+    POLICY_CONSTRAINTS = ObjectIdentifier("2.5.29.36")
+    EXTENDED_KEY_USAGE = ObjectIdentifier("2.5.29.37")
+    FRESHEST_CRL = ObjectIdentifier("2.5.29.46")
+    INHIBIT_ANY_POLICY = ObjectIdentifier("2.5.29.54")
+    AUTHORITY_INFORMATION_ACCESS = ObjectIdentifier("1.3.6.1.5.5.7.1.1")
+    SUBJECT_INFORMATION_ACCESS = ObjectIdentifier("1.3.6.1.5.5.7.1.11")
+    OCSP_NO_CHECK = ObjectIdentifier("1.3.6.1.5.5.7.48.1.5")
+
+
 OID_CRL_REASON = ObjectIdentifier("2.5.29.21")
 OID_INVALIDITY_DATE = ObjectIdentifier("2.5.29.24")
 OID_CERTIFICATE_ISSUER = ObjectIdentifier("2.5.29.29")
-OID_NAME_CONSTRAINTS = ObjectIdentifier("2.5.29.30")
-OID_CRL_DISTRIBUTION_POINTS = ObjectIdentifier("2.5.29.31")
-OID_CERTIFICATE_POLICIES = ObjectIdentifier("2.5.29.32")
-OID_POLICY_MAPPINGS = ObjectIdentifier("2.5.29.33")
-OID_AUTHORITY_KEY_IDENTIFIER = ObjectIdentifier("2.5.29.35")
-OID_POLICY_CONSTRAINTS = ObjectIdentifier("2.5.29.36")
-OID_EXTENDED_KEY_USAGE = ObjectIdentifier("2.5.29.37")
-OID_FRESHEST_CRL = ObjectIdentifier("2.5.29.46")
-OID_INHIBIT_ANY_POLICY = ObjectIdentifier("2.5.29.54")
-OID_AUTHORITY_INFORMATION_ACCESS = ObjectIdentifier("1.3.6.1.5.5.7.1.1")
-OID_SUBJECT_INFORMATION_ACCESS = ObjectIdentifier("1.3.6.1.5.5.7.1.11")
-OID_OCSP_NO_CHECK = ObjectIdentifier("1.3.6.1.5.5.7.48.1.5")
 
 OID_COMMON_NAME = ObjectIdentifier("2.5.4.3")
 OID_COUNTRY_NAME = ObjectIdentifier("2.5.4.6")
@@ -71,36 +74,38 @@
 OID_DOMAIN_COMPONENT = ObjectIdentifier("0.9.2342.19200300.100.1.25")
 OID_EMAIL_ADDRESS = ObjectIdentifier("1.2.840.113549.1.9.1")
 
-OID_RSA_WITH_MD5 = ObjectIdentifier("1.2.840.113549.1.1.4")
-OID_RSA_WITH_SHA1 = ObjectIdentifier("1.2.840.113549.1.1.5")
-OID_RSA_WITH_SHA224 = ObjectIdentifier("1.2.840.113549.1.1.14")
-OID_RSA_WITH_SHA256 = ObjectIdentifier("1.2.840.113549.1.1.11")
-OID_RSA_WITH_SHA384 = ObjectIdentifier("1.2.840.113549.1.1.12")
-OID_RSA_WITH_SHA512 = ObjectIdentifier("1.2.840.113549.1.1.13")
-OID_ECDSA_WITH_SHA1 = ObjectIdentifier("1.2.840.10045.4.1")
-OID_ECDSA_WITH_SHA224 = ObjectIdentifier("1.2.840.10045.4.3.1")
-OID_ECDSA_WITH_SHA256 = ObjectIdentifier("1.2.840.10045.4.3.2")
-OID_ECDSA_WITH_SHA384 = ObjectIdentifier("1.2.840.10045.4.3.3")
-OID_ECDSA_WITH_SHA512 = ObjectIdentifier("1.2.840.10045.4.3.4")
-OID_DSA_WITH_SHA1 = ObjectIdentifier("1.2.840.10040.4.3")
-OID_DSA_WITH_SHA224 = ObjectIdentifier("2.16.840.1.101.3.4.3.1")
-OID_DSA_WITH_SHA256 = ObjectIdentifier("2.16.840.1.101.3.4.3.2")
+
+class SignatureAlgorithmOID(object):
+    RSA_WITH_MD5 = ObjectIdentifier("1.2.840.113549.1.1.4")
+    RSA_WITH_SHA1 = ObjectIdentifier("1.2.840.113549.1.1.5")
+    RSA_WITH_SHA224 = ObjectIdentifier("1.2.840.113549.1.1.14")
+    RSA_WITH_SHA256 = ObjectIdentifier("1.2.840.113549.1.1.11")
+    RSA_WITH_SHA384 = ObjectIdentifier("1.2.840.113549.1.1.12")
+    RSA_WITH_SHA512 = ObjectIdentifier("1.2.840.113549.1.1.13")
+    ECDSA_WITH_SHA1 = ObjectIdentifier("1.2.840.10045.4.1")
+    ECDSA_WITH_SHA224 = ObjectIdentifier("1.2.840.10045.4.3.1")
+    ECDSA_WITH_SHA256 = ObjectIdentifier("1.2.840.10045.4.3.2")
+    ECDSA_WITH_SHA384 = ObjectIdentifier("1.2.840.10045.4.3.3")
+    ECDSA_WITH_SHA512 = ObjectIdentifier("1.2.840.10045.4.3.4")
+    DSA_WITH_SHA1 = ObjectIdentifier("1.2.840.10040.4.3")
+    DSA_WITH_SHA224 = ObjectIdentifier("2.16.840.1.101.3.4.3.1")
+    DSA_WITH_SHA256 = ObjectIdentifier("2.16.840.1.101.3.4.3.2")
 
 _SIG_OIDS_TO_HASH = {
-    OID_RSA_WITH_MD5.dotted_string: hashes.MD5(),
-    OID_RSA_WITH_SHA1.dotted_string: hashes.SHA1(),
-    OID_RSA_WITH_SHA224.dotted_string: hashes.SHA224(),
-    OID_RSA_WITH_SHA256.dotted_string: hashes.SHA256(),
-    OID_RSA_WITH_SHA384.dotted_string: hashes.SHA384(),
-    OID_RSA_WITH_SHA512.dotted_string: hashes.SHA512(),
-    OID_ECDSA_WITH_SHA1.dotted_string: hashes.SHA1(),
-    OID_ECDSA_WITH_SHA224.dotted_string: hashes.SHA224(),
-    OID_ECDSA_WITH_SHA256.dotted_string: hashes.SHA256(),
-    OID_ECDSA_WITH_SHA384.dotted_string: hashes.SHA384(),
-    OID_ECDSA_WITH_SHA512.dotted_string: hashes.SHA512(),
-    OID_DSA_WITH_SHA1.dotted_string: hashes.SHA1(),
-    OID_DSA_WITH_SHA224.dotted_string: hashes.SHA224(),
-    OID_DSA_WITH_SHA256.dotted_string: hashes.SHA256()
+    SignatureAlgorithmOID.RSA_WITH_MD5.dotted_string: hashes.MD5(),
+    SignatureAlgorithmOID.RSA_WITH_SHA1.dotted_string: hashes.SHA1(),
+    SignatureAlgorithmOID.RSA_WITH_SHA224.dotted_string: hashes.SHA224(),
+    SignatureAlgorithmOID.RSA_WITH_SHA256.dotted_string: hashes.SHA256(),
+    SignatureAlgorithmOID.RSA_WITH_SHA384.dotted_string: hashes.SHA384(),
+    SignatureAlgorithmOID.RSA_WITH_SHA512.dotted_string: hashes.SHA512(),
+    SignatureAlgorithmOID.ECDSA_WITH_SHA1.dotted_string: hashes.SHA1(),
+    SignatureAlgorithmOID.ECDSA_WITH_SHA224.dotted_string: hashes.SHA224(),
+    SignatureAlgorithmOID.ECDSA_WITH_SHA256.dotted_string: hashes.SHA256(),
+    SignatureAlgorithmOID.ECDSA_WITH_SHA384.dotted_string: hashes.SHA384(),
+    SignatureAlgorithmOID.ECDSA_WITH_SHA512.dotted_string: hashes.SHA512(),
+    SignatureAlgorithmOID.DSA_WITH_SHA1.dotted_string: hashes.SHA1(),
+    SignatureAlgorithmOID.DSA_WITH_SHA224.dotted_string: hashes.SHA224(),
+    SignatureAlgorithmOID.DSA_WITH_SHA256.dotted_string: hashes.SHA256()
 }
 
 OID_SERVER_AUTH = ObjectIdentifier("1.3.6.1.5.5.7.3.1")
@@ -133,47 +138,47 @@
     OID_PSEUDONYM: "pseudonym",
     OID_DOMAIN_COMPONENT: "domainComponent",
     OID_EMAIL_ADDRESS: "emailAddress",
-    OID_RSA_WITH_MD5: "md5WithRSAEncryption",
-    OID_RSA_WITH_SHA1: "sha1WithRSAEncryption",
-    OID_RSA_WITH_SHA224: "sha224WithRSAEncryption",
-    OID_RSA_WITH_SHA256: "sha256WithRSAEncryption",
-    OID_RSA_WITH_SHA384: "sha384WithRSAEncryption",
-    OID_RSA_WITH_SHA512: "sha512WithRSAEncryption",
-    OID_ECDSA_WITH_SHA1: "ecdsa-with-SHA1",
-    OID_ECDSA_WITH_SHA224: "ecdsa-with-SHA224",
-    OID_ECDSA_WITH_SHA256: "ecdsa-with-SHA256",
-    OID_ECDSA_WITH_SHA384: "ecdsa-with-SHA384",
-    OID_ECDSA_WITH_SHA512: "ecdsa-with-SHA512",
-    OID_DSA_WITH_SHA1: "dsa-with-sha1",
-    OID_DSA_WITH_SHA224: "dsa-with-sha224",
-    OID_DSA_WITH_SHA256: "dsa-with-sha256",
+    SignatureAlgorithmOID.RSA_WITH_MD5: "md5WithRSAEncryption",
+    SignatureAlgorithmOID.RSA_WITH_SHA1: "sha1WithRSAEncryption",
+    SignatureAlgorithmOID.RSA_WITH_SHA224: "sha224WithRSAEncryption",
+    SignatureAlgorithmOID.RSA_WITH_SHA256: "sha256WithRSAEncryption",
+    SignatureAlgorithmOID.RSA_WITH_SHA384: "sha384WithRSAEncryption",
+    SignatureAlgorithmOID.RSA_WITH_SHA512: "sha512WithRSAEncryption",
+    SignatureAlgorithmOID.ECDSA_WITH_SHA1: "ecdsa-with-SHA1",
+    SignatureAlgorithmOID.ECDSA_WITH_SHA224: "ecdsa-with-SHA224",
+    SignatureAlgorithmOID.ECDSA_WITH_SHA256: "ecdsa-with-SHA256",
+    SignatureAlgorithmOID.ECDSA_WITH_SHA384: "ecdsa-with-SHA384",
+    SignatureAlgorithmOID.ECDSA_WITH_SHA512: "ecdsa-with-SHA512",
+    SignatureAlgorithmOID.DSA_WITH_SHA1: "dsa-with-sha1",
+    SignatureAlgorithmOID.DSA_WITH_SHA224: "dsa-with-sha224",
+    SignatureAlgorithmOID.DSA_WITH_SHA256: "dsa-with-sha256",
     OID_SERVER_AUTH: "serverAuth",
     OID_CLIENT_AUTH: "clientAuth",
     OID_CODE_SIGNING: "codeSigning",
     OID_EMAIL_PROTECTION: "emailProtection",
     OID_TIME_STAMPING: "timeStamping",
     OID_OCSP_SIGNING: "OCSPSigning",
-    OID_SUBJECT_DIRECTORY_ATTRIBUTES: "subjectDirectoryAttributes",
-    OID_SUBJECT_KEY_IDENTIFIER: "subjectKeyIdentifier",
-    OID_KEY_USAGE: "keyUsage",
-    OID_SUBJECT_ALTERNATIVE_NAME: "subjectAltName",
-    OID_ISSUER_ALTERNATIVE_NAME: "issuerAltName",
-    OID_BASIC_CONSTRAINTS: "basicConstraints",
+    ExtensionOID.SUBJECT_DIRECTORY_ATTRIBUTES: "subjectDirectoryAttributes",
+    ExtensionOID.SUBJECT_KEY_IDENTIFIER: "subjectKeyIdentifier",
+    ExtensionOID.KEY_USAGE: "keyUsage",
+    ExtensionOID.SUBJECT_ALTERNATIVE_NAME: "subjectAltName",
+    ExtensionOID.ISSUER_ALTERNATIVE_NAME: "issuerAltName",
+    ExtensionOID.BASIC_CONSTRAINTS: "basicConstraints",
     OID_CRL_REASON: "cRLReason",
     OID_INVALIDITY_DATE: "invalidityDate",
     OID_CERTIFICATE_ISSUER: "certificateIssuer",
-    OID_NAME_CONSTRAINTS: "nameConstraints",
-    OID_CRL_DISTRIBUTION_POINTS: "cRLDistributionPoints",
-    OID_CERTIFICATE_POLICIES: "certificatePolicies",
-    OID_POLICY_MAPPINGS: "policyMappings",
-    OID_AUTHORITY_KEY_IDENTIFIER: "authorityKeyIdentifier",
-    OID_POLICY_CONSTRAINTS: "policyConstraints",
-    OID_EXTENDED_KEY_USAGE: "extendedKeyUsage",
-    OID_FRESHEST_CRL: "freshestCRL",
-    OID_INHIBIT_ANY_POLICY: "inhibitAnyPolicy",
-    OID_AUTHORITY_INFORMATION_ACCESS: "authorityInfoAccess",
-    OID_SUBJECT_INFORMATION_ACCESS: "subjectInfoAccess",
-    OID_OCSP_NO_CHECK: "OCSPNoCheck",
+    ExtensionOID.NAME_CONSTRAINTS: "nameConstraints",
+    ExtensionOID.CRL_DISTRIBUTION_POINTS: "cRLDistributionPoints",
+    ExtensionOID.CERTIFICATE_POLICIES: "certificatePolicies",
+    ExtensionOID.POLICY_MAPPINGS: "policyMappings",
+    ExtensionOID.AUTHORITY_KEY_IDENTIFIER: "authorityKeyIdentifier",
+    ExtensionOID.POLICY_CONSTRAINTS: "policyConstraints",
+    ExtensionOID.EXTENDED_KEY_USAGE: "extendedKeyUsage",
+    ExtensionOID.FRESHEST_CRL: "freshestCRL",
+    ExtensionOID.INHIBIT_ANY_POLICY: "inhibitAnyPolicy",
+    ExtensionOID.AUTHORITY_INFORMATION_ACCESS: "authorityInfoAccess",
+    ExtensionOID.SUBJECT_INFORMATION_ACCESS: "subjectInfoAccess",
+    ExtensionOID.OCSP_NO_CHECK: "OCSPNoCheck",
     OID_OCSP: "OCSP",
     OID_CA_ISSUERS: "caIssuers",
     OID_CPS_QUALIFIER: "id-qt-cps",