Question $22$

Not yet answered

Which of the following statement $($s$)$ is $($are$)$ correct?

$1.$ Cryptography does not mean only encryption and decryption.

$2.$ The Electronic Code Book $($ECB$)$ is a secure mode of operation for block ciphers.

$3.$ PKl is needed to validate and verify public keys.

$4.$ In a digital signature scheme, the signer signs a message with his$/$her public key