Refactor EC public key construction to share more code (#14285)

Author: alex

ci-constraints-requirements.txt

@@ -49,7 +49,7 @@ coverage==7.6.1 ; python_full_version < '3.9'
     # via pytest-cov
 coverage==7.10.7 ; python_full_version == '3.9.*'
     # via pytest-cov
-coverage==7.13.1 ; python_full_version >= '3.10'
+coverage==7.13.4 ; python_full_version >= '3.10'
     # via pytest-cov
 dependency-groups==1.3.1
     # via nox
@@ -316,7 +316,7 @@ urllib3==2.2.3 ; python_full_version < '3.9'
     # via requests
 urllib3==2.6.3 ; python_full_version >= '3.9'
     # via requests
-uv==0.10.0
+uv==0.10.1
     # via nox
 virtualenv==20.36.1
     # via nox

src/rust/src/backend/ec.rs

@@ -135,12 +135,10 @@ pub(crate) fn public_key_from_pkey(
 ) -> CryptographyResult<ECPublicKey> {
     let ec = pkey.ec_key()?;
     let curve = py_curve_from_curve(py, ec.group())?;
-    check_key_infinity(&ec)?;
-    Ok(ECPublicKey {
-        pkey: pkey.to_owned(),
-        curve: curve.into(),
-    })
+
+    ECPublicKey::new(pkey.to_owned(), curve.into())
 }
+
 #[pyo3::pyfunction]
 #[pyo3(signature = (curve, backend=None))]
 fn generate_private_key(
@@ -198,10 +196,7 @@ fn from_public_bytes(
     let ec = openssl::ec::EcKey::from_public_key(&curve, &point)?;
     let pkey = openssl::pkey::PKey::from_ec_key(ec)?;
 
-    Ok(ECPublicKey {
-        pkey,
-        curve: py_curve.into(),
-    })
+    ECPublicKey::new(pkey, py_curve.into())
 }
 
 #[pyo3::pymethods]
@@ -382,6 +377,18 @@ impl ECPrivateKey {
     }
 }
 
+impl ECPublicKey {
+    fn new(
+        pkey: openssl::pkey::PKey<openssl::pkey::Public>,
+        curve: pyo3::Py<pyo3::PyAny>,
+    ) -> CryptographyResult<ECPublicKey> {
+        let ec = pkey.ec_key()?;
+        check_key_infinity(&ec)?;
+
+        Ok(ECPublicKey { pkey, curve })
+    }
+}
+
 #[pyo3::pymethods]
 impl ECPublicKey {
     #[getter]
@@ -628,10 +635,7 @@ impl EllipticCurvePublicNumbers {
 
         let pkey = openssl::pkey::PKey::from_ec_key(public_key)?;
 
-        Ok(ECPublicKey {
-            pkey,
-            curve: self.curve.clone_ref(py),
-        })
+        ECPublicKey::new(pkey, self.curve.clone_ref(py))
     }
 
     fn __eq__(