Fix TypeError when passing INFINITY to VerifyingKey.from_public_point()

src/ecdsa/ecdsa.py

@@ -148,6 +148,8 @@ def __init__(self, generator, point, verify=True):
         self.point = point
         n = generator.order()
         p = self.curve.p()
+        if point == ellipticcurve.INFINITY:
+            raise InvalidPointError("The public point is the point at infinity.")
         if not (0 <= point.x() < p) or not (0 <= point.y() < p):
             raise InvalidPointError(
                 "The public point has x or y out of range."

src/ecdsa/keys.py

@@ -162,6 +162,8 @@ def from_public_point(
         self = cls(_error__please_use_generate=True)
         if isinstance(curve.curve, CurveEdTw):
             raise ValueError("Method incompatible with Edwards curves")
+        if point == ellipticcurve.INFINITY:
+            raise MalformedPointError("Cannot use the point at infinity as a public key")
         if not isinstance(point, ellipticcurve.PointJacobi):
             point = ellipticcurve.PointJacobi.from_affine(point)
         self.curve = curve

src/ecdsa/test_pyecdsa.py

@@ -65,7 +65,7 @@
     curve_brainpoolp384r1,
     curve_brainpoolp512r1,
 )
-from .ellipticcurve import Point
+from .ellipticcurve import Point, INFINITY
 from . import der
 from . import rfc6979
 from . import ecdsa
@@ -957,6 +957,12 @@ def test_decoding_with_point_at_infinity(self):
         with self.assertRaises(MalformedPointError):
             VerifyingKey.from_string(b"\x00")
 
+    def test_from_public_point_with_infinity_raises_malformed(self):
+        # passing INFINITY to from_public_point must raise MalformedPointError,
+        # not TypeError (GitHub issue #341)
+        with self.assertRaises(MalformedPointError):
+            VerifyingKey.from_public_point(INFINITY)
+
     def test_not_lying_on_curve(self):
         enc = number_to_string(NIST192p.curve.p(), NIST192p.curve.p() + 1)