def test_chacha_256bit_key(self):
msg2 = unhexlify("12345678901234567890123456")
key2 = "z" * 32 # 256-bit key
iv2 = "b" * 8
ciphertext2 = chacha(key2, iv2, msg2)
assert hexlify(ciphertext2) == b"5b7e78078d16c5efb7c46aa2a3"
assert chacha(key2, iv2, ciphertext2) == msg2
def test_chacha_128bit_key(self):
msg1 = unhexlify("12345678901234567890123456")
key1 = "x" * 16 # 128-bit key
iv1 = "a" * 8
ciphertext1 = chacha(key1, iv1, msg1)
assert hexlify(ciphertext1) == b"f4d00b7237791f237a2ddebd20"
assert chacha(key1, iv1, ciphertext1) == msg1
def decrypt(key, cipher):
"""Decrypts the msg using chacha20
Args:
key (str): A 16 byte key that will be used for decryption.
cipher (str): A message to be decrypted
Returns:
str: The decrypted msg
Raises:
ValueError: If `key` is not 16 bytes
"""
if len(key) != 16:
raise ValueError('key must be 16 bytes')
iv = cipher[:8]
msg = chacha(key, iv, cipher[8:])
return msg
def encrypt(key, msg):
"""Encrypts the msg using chacha20
Args:
key (bytes): A 16 byte key that will be used for encryption.
msg (bytes): A message to be encrypted
Returns:
str: A string where the first 8 bytes represent the iv
used in the encryption process then followed by
the encrypted msg.
Raises:
ValueError: If `key` is not 16 bytes
"""
if len(key) != 16:
raise ValueError('key must be 16 bytes')
iv = PuzzleSolver.compute_rand(64) # 8 byte iv
cipher = chacha(key, iv, msg)
return iv + cipher
def decrypt(key, cipher):
iv = cipher[:8]
msg = chacha(key, iv, cipher[8:])
return msg
def encrypt(key, msg):
iv = Puzzle_Solver.compute_rand(64) # 8 byte iv
cipher = chacha(key, iv, msg)
return iv + cipher