4 files changed, 57 insertions, 1 deletions
diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 5a6d4b54..e4c747c8 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -20,6 +20,8 @@ Changelog
 * **BACKWARDS INCOMPATIBLE**: Removed ``cryptography.x509.Certificate.serial``,
   which had been deprecated for nearly 3 years. Use
   :attr:`~cryptography.x509.Certificate.serial_number` instead.
+* Add support for easily mapping an object identifier to its elliptic curve
+  class via :func:`~cryptography.hazmat.primitives.asymmetric.ec.get_curve_for_oid`.
 
 .. _v2-5:
 
diff --git a/docs/hazmat/primitives/asymmetric/ec.rst b/docs/hazmat/primitives/asymmetric/ec.rst
index d89fde3d..0035e5b0 100644
--- a/docs/hazmat/primitives/asymmetric/ec.rst
+++ b/docs/hazmat/primitives/asymmetric/ec.rst
@@ -926,6 +926,21 @@ Elliptic Curve Object Identifiers
 
         Corresponds to the dotted string ``"1.3.132.0.39"``.
 
+.. function:: get_curve_for_oid(oid)
+
+    .. versionadded:: 2.6
+
+    A function that takes an :class:`~cryptography.x509.ObjectIdentifier`
+    and returns the associated elliptic curve class.
+
+    :param oid: An instance of
+        :class:`~cryptography.x509.ObjectIdentifier`.
+
+    :returns: The matching elliptic curve class. The returned class conforms
+        to the :class:`EllipticCurve` interface.
+
+    :raises LookupError: Raised if no elliptic curve is found that matches
+        the provided object identifier.
 
 .. _`FIPS 186-3`: https://csrc.nist.gov/csrc/media/publications/fips/186/3/archive/2009-06-25/documents/fips_186-3.pdf
 .. _`FIPS 186-4`: https://csrc.nist.gov/publications/detail/fips/186/4/final
diff --git a/src/cryptography/hazmat/primitives/asymmetric/ec.py b/src/cryptography/hazmat/primitives/asymmetric/ec.py
index 1de0976a..529391f9 100644
--- a/src/cryptography/hazmat/primitives/asymmetric/ec.py
+++ b/src/cryptography/hazmat/primitives/asymmetric/ec.py
@@ -465,3 +465,36 @@ class EllipticCurvePrivateNumbers(object):
 
 class ECDH(object):
     pass
+
+
+_OID_TO_CURVE = {
+    EllipticCurveOID.SECP192R1: SECP192R1,
+    EllipticCurveOID.SECP224R1: SECP224R1,
+    EllipticCurveOID.SECP256K1: SECP256K1,
+    EllipticCurveOID.SECP256R1: SECP256R1,
+    EllipticCurveOID.SECP384R1: SECP384R1,
+    EllipticCurveOID.SECP521R1: SECP521R1,
+    EllipticCurveOID.BRAINPOOLP256R1: BrainpoolP256R1,
+    EllipticCurveOID.BRAINPOOLP384R1: BrainpoolP384R1,
+    EllipticCurveOID.BRAINPOOLP512R1: BrainpoolP512R1,
+    EllipticCurveOID.SECT163K1: SECT163K1,
+    EllipticCurveOID.SECT163R2: SECT163R2,
+    EllipticCurveOID.SECT233K1: SECT233K1,
+    EllipticCurveOID.SECT233R1: SECT233R1,
+    EllipticCurveOID.SECT283K1: SECT283K1,
+    EllipticCurveOID.SECT283R1: SECT283R1,
+    EllipticCurveOID.SECT409K1: SECT409K1,
+    EllipticCurveOID.SECT409R1: SECT409R1,
+    EllipticCurveOID.SECT571K1: SECT571K1,
+    EllipticCurveOID.SECT571R1: SECT571R1,
+}
+
+
+def get_curve_for_oid(oid):
+    try:
+        return _OID_TO_CURVE[oid]
+    except KeyError:
+        raise LookupError(
+            "The provided object identifier has no matching elliptic "
+            "curve class"
+        )
diff --git a/tests/hazmat/primitives/test_ec.py b/tests/hazmat/primitives/test_ec.py
index 1f3a67d3..cd30223c 100644
--- a/tests/hazmat/primitives/test_ec.py
+++ b/tests/hazmat/primitives/test_ec.py
@@ -11,7 +11,7 @@ from binascii import hexlify
 
 import pytest
 
-from cryptography import exceptions, utils
+from cryptography import exceptions, utils, x509
 from cryptography.hazmat.backends.interfaces import (
     EllipticCurveBackend, PEMSerializationBackend
 )
@@ -71,6 +71,12 @@ def _skip_exchange_algorithm_unsupported(backend, algorithm, curve):
         )
 
 
+def test_get_curve_for_oid():
+    assert ec.get_curve_for_oid(ec.EllipticCurveOID.SECP256R1) == ec.SECP256R1
+    with pytest.raises(LookupError):
+        ec.get_curve_for_oid(x509.ObjectIdentifier("1.1.1.1"))
+
+
 @utils.register_interface(ec.EllipticCurve)
 class DummyCurve(object):
     name = "dummy-curve"