add IDP OID and docs (#4533)

diff --git a/docs/x509/reference.rst b/docs/x509/reference.rst
index 07a692a..5e81491 100644
--- a/docs/x509/reference.rst
+++ b/docs/x509/reference.rst
@@ -2934,6 +2934,12 @@
         Corresponds to the dotted string ``"2.5.29.46"``. The identifier for the
         :class:`~cryptography.x509.FreshestCRL` extension type.
 
+    .. attribute:: ISSUING_DISTRIBUTION_POINT
+
+        .. versionadded:: 2.4
+
+        Corresponds to the dotted string ``"2.5.29.28"``.
+
 
 .. class:: CRLEntryExtensionOID
 
diff --git a/src/cryptography/x509/oid.py b/src/cryptography/x509/oid.py
index bc65464..d121a80 100644
--- a/src/cryptography/x509/oid.py
+++ b/src/cryptography/x509/oid.py
@@ -82,6 +82,7 @@
     EXTENDED_KEY_USAGE = ObjectIdentifier("2.5.29.37")
     FRESHEST_CRL = ObjectIdentifier("2.5.29.46")
     INHIBIT_ANY_POLICY = ObjectIdentifier("2.5.29.54")
+    ISSUING_DISTRIBUTION_POINT = ObjectIdentifier("2.5.29.28")
     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")
@@ -265,6 +266,9 @@
     ExtensionOID.EXTENDED_KEY_USAGE: "extendedKeyUsage",
     ExtensionOID.FRESHEST_CRL: "freshestCRL",
     ExtensionOID.INHIBIT_ANY_POLICY: "inhibitAnyPolicy",
+    ExtensionOID.ISSUING_DISTRIBUTION_POINT: (
+        "issuingDistributionPoint"
+    ),
     ExtensionOID.AUTHORITY_INFORMATION_ACCESS: "authorityInfoAccess",
     ExtensionOID.SUBJECT_INFORMATION_ACCESS: "subjectInfoAccess",
     ExtensionOID.OCSP_NO_CHECK: "OCSPNoCheck",