/
solver.py
executable file
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/
solver.py
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import gmpy
from Crypto.Util.number import *
from Crypto.Cipher import AES
f = open("enc.txt", "r")
A = []
for line in f:
a = int(line.strip())
A.append(a)
f.close()
X = [A[i]-A[i-1]-1 for i in xrange(1, len(A))]
q = X[0]
for x in X:
q = gmpy.gcd(q, x)
assert gmpy.is_prime(q)
print "[+]q:", q
# p = 2 * p1 * p2 -1
p1 = 9090368507916642523150386537322321669636426087368916042946887058939035329547274618743911402935105936038626517888669029591219526735351668782037241434579031
p2 = 9090368507916642523150386537322321669636426087368916042946887058939035329547274618743911402935105936038626517888669029591219526735351668782037241444579211
print "[+]p1:", p1
print "[+]p2:", p2
assert (p2 - p1 > 10**8) == 0
rand = (A[0] % q) - 1
print "[+]rand:", rand
bits = ""
for i, a in enumerate(A):
m = (a-(rand+i+1))/(q*(rand+i))
if pow(m, 2*p2, q) == 1:
bits += '0'
elif pow(m, 2*p1, q) == 1:
bits += '1'
else:
print "error"
exit()
benc = long_to_bytes(int(bits, 2))
key = long_to_bytes(rand)[:16]
IV = long_to_bytes(rand)[16:32]
aes = AES.new(key, AES.MODE_CBC, IV=IV)
flag = aes.decrypt(benc)
print flag