Created
October 4, 2015 20:14
-
-
Save rikaardhosein/57c91dcbdd9af7a6ab43 to your computer and use it in GitHub Desktop.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
from z3 import * | |
ciphertext = "320b1c5900180a034c74441819004557415b0e0d1a316918011845524147384f5700264f48091e4500110e41030d1203460b1d0752150411541b455741520544111d0000131e0159110f0c16451b0f1c4a74120a170d460e13001e120a1106431e0c1c0a0a1017135a4e381b16530f330006411953664334593654114e114c09532f271c490630110e0b0b".decode("hex") | |
length = len(ciphertext) | |
ct = [ ord(ciphertext[i]) for i in range(0,length) ] | |
def encrypt(s): | |
c = [] | |
space = IntVal(0xa) | |
for i in range(0, length): | |
pos = space+i | |
idx = If( pos < (length-1), space+i, space) | |
val = Select(s,i) ^ Select(s, idx) | |
c.append(val) | |
space = If( (Select(s,i)&1) == 0, space+1, space-1) | |
return c | |
s = Solver() | |
A = Array('plaintext', IntSort(), BitVecSort(8)) | |
solution = encrypt(A) | |
for i in range(0, length): | |
s.add(solution[i] == ct[i]) | |
s.check() | |
k = s.model() | |
solution= k[A].as_list() | |
solution = solution[:len(solution)-1] | |
plaintext = {} | |
for t in solution: | |
idx = t[0].as_long() | |
val = t[1].as_long() | |
plaintext[idx] = chr(val) | |
print (''.join([plaintext[i] for i in range(0,length)])) |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment