Приветствую!

*** MAKS TV [2020-03-24 01:40]:
>Здравствуйте, какого типа должен быть key и data?

Для какой функции и библиотеки?
В pygost.gost28147 везде вот вроде бы прописано:

    def ecb(key, data, ...):
        [...]
        :param bytes key: encryption key
        :param data: plaintext
        :type data: bytes, multiple of BLOCKSIZE
        [...]

    def cbc_encrypt(key, data, ...):
        [...]
        :param bytes key: encryption key
        :param bytes data: plaintext
        [...]

    def cbc_decrypt(key, data, ...):
        [...]
        :param bytes key: encryption key
        :param bytes data: ciphertext
        [...]

    def cnt(key, data, ...):
        [...]
        :param bytes key: encryption key
        :param bytes data: plaintext
        [...]

    def cfb_encrypt(key, data, ...):
        [...]
        :param bytes key: encryption key
        :param bytes data: plaintext
        [...]

    def cfb_decrypt(key, data, ...):
        [...]
        :param bytes key: encryption key
        :param bytes data: plaintext
        [...]

-- 
Sergey Matveev (http://www.stargrave.org/)
OpenPGP: CF60 E89A 5923 1E76 E263  6422 AE1A 8109 E498 57EF