Add comments in example.py

Author: pspaul

example.py

@@ -5,7 +5,11 @@
 
 import requests
 
-
+# This function has to be implemented and will be passed to the PaddingOracle constructor.
+# It gets a hex encoded cipher text and has to return True if it can be decrypted successfully,
+# False otherwise.
+# 
+# Here is an example implementation that I used for P.W.N. CTF 2018.
 def oracle(cipher_hex):
     headers = {'Cookie': 'vals={}'.format(cipher_hex)}
     r = requests.get('http://converter.uni.hctf.fun/convert', headers=headers)
@@ -17,9 +21,11 @@ def oracle(cipher_hex):
         return False
 
 
+# Instantiate the helper with the oracle implementation
 o = PaddingOracle(oracle, max_retries=-1)
 
-# Decrypt the plain text
+# Decrypt the plain text.
+# To make the guesswork faster, use an alphabet optimized for JSON data.
 cipher = 'b5290bd594ba08fa58b1d5c7a19f876c338191a51eeeac94c2b434bdb8adbfb8596f996d6eddca93c059e3dc35f7bef36b57a5611250ec4528c11e1573799d2178c54c034b9ea8fda8ae9a4a41c67763'
 plain, padding = o.decrypt(cipher, optimized_alphabet=json_alphabet())
 print('Plaintext: {}'.format(plain))