def has_valid_padding(cipher, init_vector):
"""Checks if cipher has valid padding."""
try:
Crypto.decrypt_aes(cipher, key, AES.MODE_CBC, init_vector)
except ValueError:
return False
return True
def has_valid_padding(cipher, init_vector):
"""Checks if cipher has valid padding."""
try:
Crypto.decrypt_aes(cipher, key, AES.MODE_CBC, init_vector)
except ValueError:
return False
return True
def edit(cipher, offset, newtext):
counter = Crypto.gen_aes_stream_counter_mt19973(seed);
text = Crypto.decrypt_aes(
cipher, key, AES.MODE_CTR, counter=counter)
text = text[:offset] + newtext + text[offset + 1:]
counter = Crypto.gen_aes_stream_counter_mt19973(seed);
return Crypto.encrypt_aes(text, key, AES.MODE_CTR, counter=counter)
def edit_fast(cipher, newtext):
counter = Crypto.gen_aes_stream_counter_mt19973(seed);
text = Crypto.decrypt_aes(
cipher, key, AES.MODE_CTR, counter=counter)
text = newtext
counter = Crypto.gen_aes_stream_counter_mt19973(seed);
return Crypto.encrypt_aes(text, key, AES.MODE_CTR, counter=counter)
def test_break_random_access_read_write(self):
"""Challenge 25"""
f = open('data/25.txt')
data = f.read()
f.close()
key = 'YELLOW SUBMARINE'
known = Crypto.decrypt_aes(base64.b64decode(data), key, AES.MODE_ECB)
seed = 23232232;
def edit(cipher, offset, newtext):
counter = Crypto.gen_aes_stream_counter_mt19973(seed);
text = Crypto.decrypt_aes(
cipher, key, AES.MODE_CTR, counter=counter)
text = text[:offset] + newtext + text[offset + 1:]
counter = Crypto.gen_aes_stream_counter_mt19973(seed);
return Crypto.encrypt_aes(text, key, AES.MODE_CTR, counter=counter)
def edit_fast(cipher, newtext):
counter = Crypto.gen_aes_stream_counter_mt19973(seed);
text = Crypto.decrypt_aes(
cipher, key, AES.MODE_CTR, counter=counter)
text = newtext
counter = Crypto.gen_aes_stream_counter_mt19973(seed);
return Crypto.encrypt_aes(text, key, AES.MODE_CTR, counter=counter)
counter = Crypto.gen_aes_stream_counter_mt19973(seed);
cipher = Crypto.encrypt_aes(known, key, AES.MODE_CTR, counter=counter)
text = edit_fast(cipher, cipher)
# replacing text with cipher is same is decrypting cipher.
#for i in range(len(cipher)):
# text += edit(cipher, i, cipher[i])[i]
self.assertEqual(known, text)
def test_break_if_iv_is_same_as_key(self):
"""Challenge 27"""
key = Crypto.gen_random_key(16)
iv = key
oracle = lambda c: Crypto.decrypt_aes(c, key, AES.MODE_CBC, iv)
cipher = Crypto.encrypt_aes("X" * 48, key, AES.MODE_CBC, iv)
self.assertEquals(
key, Crypto.extract_key_if_key_is_same_as_key(cipher, oracle))
def has_admin(cipher):
"""Checks if cipher has admin."""
counter = Crypto.gen_aes_stream_counter_mt19973(3453243)
text = Crypto.decrypt_aes(cipher,
key,
AES.MODE_CTR,
counter=counter)
return text.find(';admin=true;') != -1
def test_break_if_iv_is_same_as_key(self):
"""Challenge 27"""
key = Crypto.gen_random_key(16)
iv = key
oracle = lambda c: Crypto.decrypt_aes(c, key, AES.MODE_CBC, iv)
cipher = Crypto.encrypt_aes("X"*48, key, AES.MODE_CBC, iv)
self.assertEquals(key,
Crypto.extract_key_if_key_is_same_as_key(cipher, oracle))
def test_aes_ctr_encryption(self):
"""Challenge 18"""
counter = Crypto.gen_aes_stream_counter_simple()
key = "YELLOW SUBMARINE"
cipher = base64.b64decode("L77na/nrFsKvynd6HzOoG7GHTLXsTVu9qvY/2syLX" +\
"zhPweyyMTJULu/6/kXX0KSvoOLSFQ==")
text = "Yo, VIP Let's kick it Ice, Ice, baby Ice, Ice, baby "
self.assertEqual(text, Crypto.decrypt_aes(
cipher, key, AES.MODE_CTR, counter=counter))
# another test
key = Crypto.gen_random_key(16)
text = "Let there be light!"
counter = Crypto.gen_aes_stream_counter_simple()
cipher = Crypto.encrypt_aes(text, key, AES.MODE_CTR, counter=counter)
counter = Crypto.gen_aes_stream_counter_simple()
self.assertEqual(text, Crypto.decrypt_aes(
cipher, key, AES.MODE_CTR, counter=counter))
def edit_fast(cipher, newtext):
counter = Crypto.gen_aes_stream_counter_mt19973(seed)
text = Crypto.decrypt_aes(cipher,
key,
AES.MODE_CTR,
counter=counter)
text = newtext
counter = Crypto.gen_aes_stream_counter_mt19973(seed)
return Crypto.encrypt_aes(text, key, AES.MODE_CTR, counter=counter)
def edit(cipher, offset, newtext):
counter = Crypto.gen_aes_stream_counter_mt19973(seed)
text = Crypto.decrypt_aes(cipher,
key,
AES.MODE_CTR,
counter=counter)
text = text[:offset] + newtext + text[offset + 1:]
counter = Crypto.gen_aes_stream_counter_mt19973(seed)
return Crypto.encrypt_aes(text, key, AES.MODE_CTR, counter=counter)
def test_aes_ctr_encryption(self):
"""Challenge 18"""
counter = Crypto.gen_aes_stream_counter_simple()
key = "YELLOW SUBMARINE"
cipher = base64.b64decode("L77na/nrFsKvynd6HzOoG7GHTLXsTVu9qvY/2syLX" +\
"zhPweyyMTJULu/6/kXX0KSvoOLSFQ==")
text = "Yo, VIP Let's kick it Ice, Ice, baby Ice, Ice, baby "
self.assertEqual(
text, Crypto.decrypt_aes(cipher,
key,
AES.MODE_CTR,
counter=counter))
# another test
key = Crypto.gen_random_key(16)
text = "Let there be light!"
counter = Crypto.gen_aes_stream_counter_simple()
cipher = Crypto.encrypt_aes(text, key, AES.MODE_CTR, counter=counter)
counter = Crypto.gen_aes_stream_counter_simple()
self.assertEqual(
text, Crypto.decrypt_aes(cipher,
key,
AES.MODE_CTR,
counter=counter))
def test_break_random_access_read_write(self):
"""Challenge 25"""
f = open('data/25.txt')
data = f.read()
f.close()
key = 'YELLOW SUBMARINE'
known = Crypto.decrypt_aes(base64.b64decode(data), key, AES.MODE_ECB)
seed = 23232232
def edit(cipher, offset, newtext):
counter = Crypto.gen_aes_stream_counter_mt19973(seed)
text = Crypto.decrypt_aes(cipher,
key,
AES.MODE_CTR,
counter=counter)
text = text[:offset] + newtext + text[offset + 1:]
counter = Crypto.gen_aes_stream_counter_mt19973(seed)
return Crypto.encrypt_aes(text, key, AES.MODE_CTR, counter=counter)
def edit_fast(cipher, newtext):
counter = Crypto.gen_aes_stream_counter_mt19973(seed)
text = Crypto.decrypt_aes(cipher,
key,
AES.MODE_CTR,
counter=counter)
text = newtext
counter = Crypto.gen_aes_stream_counter_mt19973(seed)
return Crypto.encrypt_aes(text, key, AES.MODE_CTR, counter=counter)
counter = Crypto.gen_aes_stream_counter_mt19973(seed)
cipher = Crypto.encrypt_aes(known, key, AES.MODE_CTR, counter=counter)
text = edit_fast(cipher, cipher)
# replacing text with cipher is same is decrypting cipher.
#for i in range(len(cipher)):
# text += edit(cipher, i, cipher[i])[i]
self.assertEqual(known, text)
def has_admin(cipher):
"""Checks if cipher has admin."""
text = Crypto.decrypt_aes(cipher, key, AES.MODE_CBC)
return text.find(';admin=true;') != -1
def has_admin(cipher):
"""Checks if cipher has admin."""
counter = Crypto.gen_aes_stream_counter_mt19973(3453243);
text = Crypto.decrypt_aes(cipher, key, AES.MODE_CTR, counter=counter)
return text.find(';admin=true;') != -1
def test_aes_decryption_ecb_mode(self):
"""Challenge 7"""
cipher = base64.b64decode(open("data/7.txt").read())
key = 'YELLOW SUBMARINE'
text = Crypto.decrypt_aes(cipher, key, AES.MODE_ECB)
self.assertEqual(open('data/plaintext.txt').read(), text)
def test_aes_decryption_ecb_mode(self):
"""Challenge 7"""
cipher = base64.b64decode(open("data/7.txt").read())
key = 'YELLOW SUBMARINE'
text = Crypto.decrypt_aes(cipher, key, AES.MODE_ECB)
self.assertEqual(open('data/plaintext.txt').read(), text)
