picoctf/misc/codebook/code.py

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2024-09-01 22:10:44 +02:00
#!/usr/bin/env python3
import random
import sys
def str_xor(secret, key):
#extend key to secret length
new_key = key
i = 0
while len(new_key) < len(secret):
new_key = new_key + key[i]
i = (i + 1) % len(key)
return "".join([chr(ord(secret_c) ^ ord(new_key_c)) for (secret_c,new_key_c) in zip(secret,new_key)])
flag_enc = chr(0x13) + chr(0x01) + chr(0x17) + chr(0x07) + chr(0x2c) + chr(0x3a) + chr(0x2f) + chr(0x1a) + chr(0x0d) + chr(0x53) + chr(0x0c) + chr(0x47) + chr(0x0a) + chr(0x5f) + chr(0x5e) + chr(0x02) + chr(0x3e) + chr(0x5a) + chr(0x56) + chr(0x5d) + chr(0x45) + chr(0x5d) + chr(0x58) + chr(0x31) + chr(0x5e) + chr(0x05) + chr(0x5f) + chr(0x53) + chr(0x5a) + chr(0x10) + chr(0x5f) + chr(0x0e) + chr(0x13)
def print_flag():
try:
codebook = open('codebook.txt', 'r').read()
password = codebook[4] + codebook[14] + codebook[13] + codebook[14] +\
codebook[23]+ codebook[25] + codebook[16] + codebook[0] +\
codebook[25]
flag = str_xor(flag_enc, password)
print(flag)
except FileNotFoundError:
print('Couldn\'t find codebook.txt. Did you download that file into the same directory as this script?')
def main():
print_flag()
if __name__ == "__main__":
main()