fix py3.2 compatibility

unhexlify("ff") doesn't work in py3.2: strings don't support the buffer
interface. It works in py3.3.

Author: warner

ecdsa/test_pyecdsa.py

@@ -568,7 +568,7 @@ def test_1(self):
         self._do(
             generator = Point(None, 0, 0, int("4000000000000000000020108A2E0CC0D99F8A5EF", 16)),
             secexp = int("09A4D6792295A7F730FC3F2B49CBC0F62E862272F", 16),
-            hsh = unhexlify("AF2BDBE1AA9B6EC1E2ADE1D694F41FC71A831D0268E9891562113D8A62ADD1BF"),
+            hsh = unhexlify(b("AF2BDBE1AA9B6EC1E2ADE1D694F41FC71A831D0268E9891562113D8A62ADD1BF")),
             hash_func = sha256,
             expected = int("23AF4074C90A02B3FE61D286D5C87F425E6BDD81B", 16))
 

ecdsa/util.py

@@ -168,7 +168,7 @@ def number_to_string(num, order):
 def number_to_string_crop(num, order):
     l = orderlen(order)
     fmt_str = "%0" + str(2*l) + "x"
-    string = binascii.unhexlify(fmt_str % num)
+    string = binascii.unhexlify((fmt_str % num).encode())
     return string[:l]
 
 def string_to_number(string):