def prepare(self, input_string):
comment1 = b'comment1=cooking%20MCs;userdata='
comment2 = b';comment2=%20like%20a%20pound%20of%20bacon'
table = str.maketrans(dict.fromkeys('=;'))
clean_input_string = input_string.decode().translate(table)
plain_text_pad = pad_pkcs(comment1 + clean_input_string.encode() + comment2, 16)
return aes128_cbc_encrypt(plain_text_pad, self.iv, self.key)
def encrypt(self, plain_text):
plain_text_pad = pad_pkcs(plain_text + b64decode(self.data), 16)
cipher_text = aes128_ecb_encrypt(plain_text_pad, self.key)
return cipher_text
def encrypt(self, plain_text):
# the difference between this challenge and challenge12 are the random bytes
plain_text_pad = pad_pkcs(
self.random_bytes + plain_text + b64decode(self.data), 16)
cipher_text = aes128_ecb_encrypt(plain_text_pad, self.key)
return cipher_text
ctr_substitution[i]['cipher'], key_stream)
print(i, ctr_substitution[i]['plain'],
len(ctr_substitution[i]['plain']), "refined:",
ctr_substitution[i]['refined'])
print("\n", count_not_refined(ctr_substitution), "texts to be refined")
# At this point, the beginning of sentences can be read, but the end is definitely not readable.
# We can conclude that the first block is correctly, and the followings are deviated due the padding chars.
# Let's try to refine our results, starting by block number two:
ctr_substitution = refine_block(ctr_substitution,
1) # 1 is the block number two
key_stream_refined = b''
for i in range(len(ctr_substitution)):
if ctr_substitution[i]['refined']:
pad_plain = pad_pkcs(ctr_substitution[i]['plain'],
16) # pad any refined text correctly
# plain xor cipher = keystream
key_stream_refined = xor_bytes(
pad_plain,
ctr_substitution[i]['cipher']) # Calculate keystream again
break
# The keystream calculated from refined only sizes two blocks.
# For the last block we use the keystream calculated before
key_stream = key_stream_refined[:32] + key_stream[32:]
# decrypt using the new keystream
print("\nSecond attempt using the new keystream:")
print("Keystream 2:", key_stream)
for i in range(len(ctr_substitution)):
if not ctr_substitution[i]['refined']:
def encrypt_profile(self, email):
'''Create profile from email and encrypt it using random key'''
profile = profile_factory.profile_for(email)
formatted_profile_pad = pad_pkcs(profile, 16)
cipher_text = aes128_ecb_encrypt(formatted_profile_pad, self.key)
return cipher_text
# Implement PKCS#7 padding
from utils import pad_pkcs
if __name__ == '__main__':
x = b"YELLOW SUBMARINE"
y = pad_pkcs(x, 20)
print(y)
def encrypt(self, str):
str_pad = pad_pkcs(str, 16)
cipher_text = aes128_cbc_encrypt(str_pad, self.iv, self.key)
return cipher_text, self.iv