def f1(plaintext):
global key
global nonce
sanitised = plaintext.replace(";","';'").replace("=","'='")
data = "comment1=cooking%20MCs;userdata="+sanitised+";comment2=%20like%20a%20pound%20of%20bacon"
return ctr(bytearray(data,"ascii"),key,nonce)
def main():
key = "YELLOW SUBMARINE"
INPUT = "L77na/nrFsKvynd6HzOoG7GHTLXsTVu9qvY/2syLXzhPweyyMTJULu/6/kXX0KSvoOLSFQ=="
nonce = 0
data = base64.b64decode(INPUT)
print(ctr(data, key, nonce))
def f2(ciphertext):
global key
global nonce
plaintext = ctr(ciphertext,key,nonce)
if ";admin=true;" in str(plaintext):
return True
else:
return False
def site_profile_token(input_str):
good_nonce = ""
for i in range(8):
good_nonce += chr(random.randint(0, 255))
input_str = input_str.replace(';', '.')
input_str = input_str.replace('=', '.')
plaintext = ('comment1=cooking%20MCs;userdata=' + input_str +
';comment2=%20like%20a%20pound%20of%20bacon;')
return [
cryptopals.ctr(plaintext, ctr_key, good_nonce, "little"), good_nonce
]
def site_profile_token(input_str):
good_nonce = ""
for i in range(8):
good_nonce += chr(random.randint(0,255))
input_str = input_str.replace(';', '.')
input_str = input_str.replace('=', '.')
plaintext = ('comment1=cooking%20MCs;userdata='
+ input_str
+ ';comment2=%20like%20a%20pound%20of%20bacon;')
return [cryptopals.ctr(plaintext, ctr_key, good_nonce, "little")
, good_nonce]
def main():
global key #put it here for the edit_api() function
global nonce #put it here for the edit_api() function
INPUT = recover_input()
key = random_aes_key()
nonce = 0
ciphertext = ctr(INPUT, key, nonce)
#print ctr(ciphertext,key,nonce)[:255]
junk = bytearray("A" * len(ciphertext), "ascii")
mask = edit_api(ciphertext, 0, junk)
keystream = xor(junk, mask)
plaintext = xor(ciphertext, keystream)
print(plaintext)
# chal19.py - Fixed-nonce CTR via substitutions
#
# Copyright (C) 2015 Andrew J. Zimolzak <*****@*****.**>,
# and licensed under GNU GPL version 3. Full notice is found in
# the file 'LICENSE' in the same directory as this file.
import base64
from cryptopals import warn, ctr, xor_str
key = open('unknown_key.txt', 'r').read().splitlines()[0]
nonce = "\x00\x00\x00\x00\x00\x00\x00\x00"
ciphertexts = []
for b64 in open('19.txt', 'r').read().splitlines():
ciphertexts = ciphertexts + [
ctr(base64.b64decode(b64), key, nonce, "little")
]
guesses = [''] * 256
for i in range(len(ciphertexts)):
# This loop is for manual use only. Serves no purpose in the final
# decryption step. Manually adjust the [i][15] number, and examine
# the printout for strings that look like slices of English text
# (mainly lowercase and spaces, few punctuation marks, no ASCII >
# 127). First char of each string is the J'th byte in the
# keystream.
for c in range(256):
if i == 0:
guesses[c] = guesses[c] + chr(c)
def edit(ciphertext, key, nonce, offset, newtext):
plaintext = cryptopals.ctr(ciphertext, key, nonce, "little")
nchars = len(newtext)
plaintext = plaintext[0:offset] + newtext + plaintext[offset+nchars:]
return cryptopals.ctr(plaintext, key, nonce, "little")
#!/usr/bin/env python
# chal18.py - Implement CTR
#
# Copyright (C) 2015 Andrew J. Zimolzak <*****@*****.**>,
# and licensed under GNU GPL version 3. Full notice is found in
# the file 'LICENSE' in the same directory as this file.
import base64
from cryptopals import warn, ctr
ciphertext = base64.b64decode(
"L77na/nrFsKvynd6HzOoG7GHTLXsTVu9qvY/2syLXzhPweyyMTJULu/6/kXX0KSvoOLSFQ==")
key = "YELLOW SUBMARINE"
nonce = "\x00\x00\x00\x00\x00\x00\x00\x00" # 8 byte nonce
plaintext = ctr(ciphertext, key, nonce, "little")
print plaintext
#### tests ####
assert plaintext[-5:] == "baby "
warn("Passed assertions (" + __file__ + ")")
def ctr_cheat(ciphertext):
return cryptopals.ctr(ciphertext, ctr_key, ctr_nonce, "little")
def profile_is_admin(cipher_nonce_list):
token = cipher_nonce_list[0]
nonce = cipher_nonce_list[1]
plaintext = cryptopals.ctr(token, ctr_key, nonce, "little")
return ';admin=true;' in plaintext
def ctr_cheat(ciphertext):
return cryptopals.ctr(ciphertext, ctr_key, ctr_nonce, "little")
def profile_token_cheat(cipher_nonce_list):
ciphertext = cipher_nonce_list[0]
nonce = cipher_nonce_list[1]
return cryptopals.ctr(ciphertext, ctr_key, nonce, "little")
#### CTR
ecb_encrypted = base64.b64decode(''.join(
open('25.txt', 'r').read().splitlines()))
plain = AES.new("YELLOW SUBMARINE", AES.MODE_ECB).decrypt(ecb_encrypted)
ctr_key = open('unknown_key.txt', 'r').read().splitlines()[0]
ctr_nonce = ""
for i in range(8):
# I believe this sets it upon import of this file, not for each
# encrypt/decrypt. Not the most secure, but in any case I don't
# use a nonce attack to "cheat" at CTR challenges.
ctr_nonce += chr(random.randint(0, 255))
ctr_ciphertext = cryptopals.ctr(plain, ctr_key, ctr_nonce, "little")
def edit(ciphertext, key, nonce, offset, newtext):
plaintext = cryptopals.ctr(ciphertext, key, nonce, "little")
nchars = len(newtext)
plaintext = plaintext[0:offset] + newtext + plaintext[offset + nchars:]
return cryptopals.ctr(plaintext, key, nonce, "little")
def edit_public(ciphertext, offset, newtext):
# closure
return edit(ciphertext, ctr_key, ctr_nonce, offset, newtext)
def ctr_cheat(ciphertext):
def edit(ciphertext, key, nonce, offset, newtext):
plaintext = cryptopals.ctr(ciphertext, key, nonce, "little")
nchars = len(newtext)
plaintext = plaintext[0:offset] + newtext + plaintext[offset + nchars:]
return cryptopals.ctr(plaintext, key, nonce, "little")
return cipher.encrypt(message)
#### CTR
ecb_encrypted = base64.b64decode(''.join(open('25.txt', 'r').
read().splitlines()))
plain = AES.new("YELLOW SUBMARINE", AES.MODE_ECB).decrypt(ecb_encrypted)
ctr_key = open('unknown_key.txt', 'r').read().splitlines()[0]
ctr_nonce = ""
for i in range(8):
# I believe this sets it upon import of this file, not for each
# encrypt/decrypt. Not the most secure, but in any case I don't
# use a nonce attack to "cheat" at CTR challenges.
ctr_nonce += chr(random.randint(0,255))
ctr_ciphertext = cryptopals.ctr(plain, ctr_key, ctr_nonce, "little")
def edit(ciphertext, key, nonce, offset, newtext):
plaintext = cryptopals.ctr(ciphertext, key, nonce, "little")
nchars = len(newtext)
plaintext = plaintext[0:offset] + newtext + plaintext[offset+nchars:]
return cryptopals.ctr(plaintext, key, nonce, "little")
def edit_public(ciphertext, offset, newtext):
# closure
return edit(ciphertext, ctr_key, ctr_nonce, offset, newtext)
def ctr_cheat(ciphertext):
return cryptopals.ctr(ciphertext, ctr_key, ctr_nonce, "little")
def profile_token_cheat(cipher_nonce_list):
def profile_token_cheat(cipher_nonce_list):
ciphertext = cipher_nonce_list[0]
nonce = cipher_nonce_list[1]
return cryptopals.ctr(ciphertext, ctr_key, nonce, "little")
#!/usr/bin/env python
# chal18.py - Implement CTR
#
# Copyright (C) 2015 Andrew J. Zimolzak <*****@*****.**>,
# and licensed under GNU GPL version 3. Full notice is found in
# the file 'LICENSE' in the same directory as this file.
import base64
from cryptopals import warn, ctr
ciphertext = base64.b64decode(
"L77na/nrFsKvynd6HzOoG7GHTLXsTVu9qvY/2syLXzhPweyyMTJULu/6/kXX0KSvoOLSFQ==")
key = "YELLOW SUBMARINE"
nonce = "\x00\x00\x00\x00\x00\x00\x00\x00" # 8 byte nonce
plaintext = ctr(ciphertext, key, nonce, "little")
print plaintext
#### tests ####
assert plaintext[-5:] == "baby "
warn("Passed assertions (" + __file__ + ")")
# chal20.py - Fixed-nonce CTR via statistics
#
# Copyright (C) 2015 Andrew J. Zimolzak <*****@*****.**>,
# and licensed under GNU GPL version 3. Full notice is found in
# the file 'LICENSE' in the same directory as this file.
import base64
from cryptopals import warn, ctr, xor_str, xor_uneq
from rkxor import break_cipher_given_keysize, xor_char_str
key = open('unknown_key.txt', 'r').read().splitlines()[0]
nonce = "\x00\x00\x00\x00\x00\x00\x00\x00"
ciphertexts = []
for b64 in open('20.txt', 'r').read().splitlines():
ciphertexts = ciphertexts + [ctr(base64.b64decode(b64),
key, nonce, "little")]
#### Decrypt the hard way (statistics) ####
maximum = 0
for i in range(len(ciphertexts)):
if len(ciphertexts[i]) > maximum:
maximum = len(ciphertexts[i])
keystream = ""
for k in range(maximum):
concat = ""
for c in ciphertexts:
try:
concat += c[k]
except IndexError:
def profile_is_admin(cipher_nonce_list):
token = cipher_nonce_list[0]
nonce = cipher_nonce_list[1]
plaintext = cryptopals.ctr(token, ctr_key, nonce, "little")
return ';admin=true;' in plaintext
