Please briefly justify your choice, especially for a false statement; otherwise, no marks will be given. $1.$ In Vigen$`$ere Cipher, for a given secret key k$,$ longer ciphertexts achieve stronger security. $2.$ According to Kerckhoffs$$s principle, the internal details of a secret key generation algorithm of a cryptosystem should be secret to make sure it remains secure$.3.$ One$-$time pad is not secure against a brute$-$force attack: upon seeing a ciphertext c$,$ a brute$-$force attacker can try each candidate key k until finding the one that was used, and output plaintext m at that point. $4.$ Securely sharing the one$-$time pad key is a major challenge in practice, but its major limitation can be solved by secret$-$sharing. $5.$ Provable security guarantees that a scheme is immune to all possible types of attacks, both known and unknown. $6.$ When proving security via establishing two libraries are interchangeable L$1$ L$2,$ the calling program A calls the functions of both libraries simultaneously to distinguish them.