Fix bug in generating EC curves

The EC curves use 'crv' to store the curve name, not curve.
Support both and make sure params['crv'] is set once generation is done or
the generated key will be non-functional as get_curve() will fail.

Signed-off-by: Simo Sorce <[email protected]>
Closes #12

Author: simo5

jwcrypto/jwk.py

@@ -250,10 +250,16 @@ def _generate_EC(self, params):
         if 'curve' in params:
             curve = params['curve']
             del params['curve']
-        key = ec.generate_private_key(self._get_curve_by_name(curve),
-                                      default_backend())
+        # 'curve' is for backwards compat, if 'crv' is defined it takes
+        # precedence
+        if 'crv' in params:
+            curve = params['crv']
+            del params['crv']
+        curve_name = self._get_curve_by_name(curve)
+        key = ec.generate_private_key(curve_name, default_backend())
         pn = key.private_numbers()
         params['kty'] = 'EC'
+        params['crv'] = curve
         params['x'] = self._encode_int(pn.public_numbers.x)
         params['y'] = self._encode_int(pn.public_numbers.y)
         params['d'] = self._encode_int(pn.private_value)

jwcrypto/tests.py

@@ -204,6 +204,18 @@ def test_generate_oct_key(self):
         E.deserialize(e, key)
         self.assertEqual(E.payload.decode('utf-8'), 'test')
 
+    def test_generate_EC_key(self):
+        # Backwards compat curve
+        key = jwk.JWK(generate='EC', curve='P-256')
+        key.get_curve('P-256')
+        # New param
+        key = jwk.JWK(generate='EC', crv='P-521')
+        key.get_curve('P-521')
+        # New param prevails
+        key = jwk.JWK(generate='EC', curve='P-256', crv='P-521')
+        key.get_curve('P-521')
+
+
 # RFC 7515 - A.1
 A1_protected = \
     [123, 34, 116, 121, 112, 34, 58, 34, 74, 87, 84, 34, 44, 13, 10, 32,