some small fixes

CTFs_and_WarGames/2014-ASIS-CTF/crypto_paillier/answer_pallier.py

@@ -0,0 +1,93 @@
+#!/usr/bin/python
+
+__author__ = "bt3gl"
+__email__ = "bt3gl@gmail.com"
+
+import decimal
+import socket
+from constants import mod
+
+def print_hex(secret):
+
+    # cutting L in the end
+    a = hex(secret)[:-1]
+
+    # cutting the \x symbol
+    b = a[2:].decode('hex')
+
+    return b
+
+
+
+def convolution(e1, e2, m2, mod):
+
+    return (e1 * e2 )%(mod*mod)
+
+
+
+def nc_paillier(mod):
+
+    # create socket
+    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+    s.connect((HOST, PORT))
+
+
+    # answer the initial question
+    s.recv(4096)
+    s.send(b'paillier')
+    s.recv(4096)
+    m = s.recv(4096)
+    m = (m.split(": ")[1]).split('\n')[0]
+    mdec = decimal.Decimal(m)
+
+
+    # encrypt 1
+    e = '1'
+    m2 = decimal.Decimal(e)
+    s.send(b'E')
+    s.recv(4096)
+    s.send(e)
+    e2 = s.recv(4096)
+    e2 = e2.split(": ")[1]
+    e2dec = decimal.Decimal(e2)
+
+
+
+    # convolute the enc messages
+    answer = convolution(mdec, e2dec, m2, mod)
+
+
+    # get the description from the answer
+    s.send(b'D')
+    s.recv(4096)
+    s.recv(4096)
+    s.send(str(answer))
+    md = s.recv(4096)
+    md = md.split(": ")[1].strip()
+
+
+
+    # get the flag, remember to add d(e(1)) = 1
+    secret = long(md) + 1
+    flag = print_hex(secret)
+    print("The flag is: ")
+    print flag
+
+
+
+
+
+if __name__ == "__main__":
+
+    # really long numbers
+    decimal.getcontext().prec = 1240
+
+    PORT = 12445
+    HOST = 'asis-ctf.ir'
+
+    nc_paillier(mod)
+
+
+
+
+