def decrypt_fp(secret_key, cipher_fp, plaintext_fp):
key = pre_process_raw(secret_key,
func=key_pre_process_func)
keys = key_schedule_s(key)[::-1]
length = len_fp(cipher_fp)
while True:
block = cipher_fp.read(8)
plaintext_block = ''.join(map(lambda x: chr(int(x, base=2)),
feistel_s(pre_process_raw(block),
keys)))
if cipher_fp.tell() == length:
plaintext_block = plaintext_block[:-ord(plaintext_block[-1])]
plaintext_fp.write(plaintext_block)
break
plaintext_fp.write(plaintext_block)
return plaintext_fp
def encrypt_fp(secret_key, plaintext_fp, cipher_fp):
key = pre_process_raw(secret_key,
func=key_pre_process_func)
keys = key_schedule_s(key)
length = len_fp(plaintext_fp)
while True:
block = plaintext_fp.read(8)
pos = plaintext_fp.tell()
block_len = len(block)
if block_len < 8:
block += padding(block_len)
pos += 8 - block_len
cipher_fp.write(''.join(map(lambda x: chr(int(x, base=2)),
feistel_s(pre_process_raw(block),
keys))))
if pos > length:
break
return cipher_fp
