add convenience methods for key_size on EC{Public,Private}Key (#3587)
diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 0e7619e..81aca4e 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -21,6 +21,12 @@
:meth:`~cryptography.hazmat.primitives.ciphers.AEADDecryptionContext.finalize_with_tag`.
* Fixed an issue preventing ``cryptography`` from compiling against
LibreSSL 2.5.x.
+* Added
+ :meth:`~cryptography.hazmat.primitives.asymmetric.ec.EllipticCurvePublicKey.key_size`
+ and
+ :meth:`~cryptography.hazmat.primitives.asymmetric.ec.EllipticCurvePrivateKey.key_size`
+ as convenience methods for determining the bit size of a secret scalar for
+ the curve.
* Accessing an unrecognized extension marked critical on an X.509 object will
no longer raise an ``UnsupportedExtension`` exception, instead an
:class:`~cryptography.x509.UnrecognizedExtension` object will be returned.
diff --git a/docs/hazmat/primitives/asymmetric/ec.rst b/docs/hazmat/primitives/asymmetric/ec.rst
index 3c595fa..46f2f5a 100644
--- a/docs/hazmat/primitives/asymmetric/ec.rst
+++ b/docs/hazmat/primitives/asymmetric/ec.rst
@@ -459,6 +459,15 @@
:return bytes: Signature.
+ .. attribute:: key_size
+
+ .. versionadded:: 1.9
+
+ :type: int
+
+ Size (in bits) of a secret scalar for the curve (as generated by
+ :func:`generate_private_key`).
+
.. class:: EllipticCurvePrivateKeyWithSerialization
@@ -565,6 +574,15 @@
:raises cryptography.exceptions.InvalidSignature: If the signature does
not validate.
+ .. attribute:: key_size
+
+ .. versionadded:: 1.9
+
+ :type: int
+
+ Size (in bits) of a secret scalar for the curve (as generated by
+ :func:`generate_private_key`).
+
.. class:: EllipticCurvePublicKeyWithSerialization
diff --git a/src/cryptography/hazmat/backends/openssl/ec.py b/src/cryptography/hazmat/backends/openssl/ec.py
index 68a35b2..3a81f91 100644
--- a/src/cryptography/hazmat/backends/openssl/ec.py
+++ b/src/cryptography/hazmat/backends/openssl/ec.py
@@ -135,6 +135,10 @@
curve = utils.read_only_property("_curve")
+ @property
+ def key_size(self):
+ return self.curve.key_size
+
def signer(self, signature_algorithm):
_check_signature_algorithm(signature_algorithm)
return _ECDSASignatureContext(
@@ -231,6 +235,10 @@
curve = utils.read_only_property("_curve")
+ @property
+ def key_size(self):
+ return self.curve.key_size
+
def verifier(self, signature, signature_algorithm):
if not isinstance(signature, bytes):
raise TypeError("signature must be bytes.")
diff --git a/src/cryptography/hazmat/primitives/asymmetric/ec.py b/src/cryptography/hazmat/primitives/asymmetric/ec.py
index a527387..7931b08 100644
--- a/src/cryptography/hazmat/primitives/asymmetric/ec.py
+++ b/src/cryptography/hazmat/primitives/asymmetric/ec.py
@@ -22,7 +22,7 @@
@abc.abstractproperty
def key_size(self):
"""
- The bit length of the base point of the curve.
+ Bit size of a secret scalar for the curve.
"""
@@ -63,6 +63,12 @@
"""
@abc.abstractproperty
+ def key_size(self):
+ """
+ Bit size of a secret scalar for the curve.
+ """
+
+ @abc.abstractproperty
def sign(self, data, signature_algorithm):
"""
Signs the data
@@ -98,6 +104,12 @@
The EllipticCurve that this key is on.
"""
+ @abc.abstractproperty
+ def key_size(self):
+ """
+ Bit size of a secret scalar for the curve.
+ """
+
@abc.abstractmethod
def public_numbers(self):
"""
diff --git a/tests/hazmat/primitives/test_ec.py b/tests/hazmat/primitives/test_ec.py
index ad4bbc5..d5db52a 100644
--- a/tests/hazmat/primitives/test_ec.py
+++ b/tests/hazmat/primitives/test_ec.py
@@ -277,6 +277,15 @@
@pytest.mark.requires_backend_interface(interface=EllipticCurveBackend)
+def test_ec_key_key_size(backend):
+ curve = ec.SECP256R1()
+ _skip_curve_unsupported(backend, curve)
+ key = ec.generate_private_key(curve, backend)
+ assert key.key_size == 256
+ assert key.public_key().key_size == 256
+
+
+@pytest.mark.requires_backend_interface(interface=EllipticCurveBackend)
class TestECWithNumbers(object):
@pytest.mark.parametrize(
("vector", "hash_type"),