add ability to precompute for verification

speed.py

@@ -20,14 +20,15 @@ def do(setup_statements, statement):
     S3 = "msg = six.b('msg')"
     S4 = "sig = sk.sign(msg)"
     S5 = "vk = sk.get_verifying_key()"
-    S6 = "vk.verify(sig, msg)"
+    S6 = "vk.precompute()"
+    S7 = "vk.verify(sig, msg)"
     # We happen to know that .generate() also calculates the
     # verifying key, which is the time-consuming part. If the code
     # were changed to lazily calculate vk, we'd need to change this
     # benchmark to loop over S5 instead of S2
     keygen = do([S1], S2)
     sign = do([S1,S2,S3], S4)
-    verf = do([S1,S2,S3,S4,S5], S6)
+    verf = do([S1,S2,S3,S4,S5,S6], S7)
     import ecdsa
     c = getattr(ecdsa, curve)
     sig = ecdsa.SigningKey.generate(c).sign(six.b("msg"))

src/ecdsa/keys.py

@@ -47,6 +47,10 @@ def from_public_point(klass, point, curve=NIST192p, hashfunc=sha1):
         self.pubkey.order = curve.order
         return self
 
+    def precompute(self):
+        self.pubkey.point = ellipticcurve.PointJacobi.from_weierstrass(
+            self.pubkey.point, True)
+
     @staticmethod
     def _from_raw_encoding(string, curve, validate_point):
         order = curve.order