?A.Rahman wants to digitally sign a message for sending to Samer so that Samer can confirm that the message came from him without any modification during transit. What key should A.Rahman use to encrypt the message digest A.Rahman's public key O A.Rahman's private key O Samer's public key O Samer's Private key O 17 ? What is HMAC Heuristic MAC function O Hash function based on MAC O MAC based on a hash functione O Hash function based on a block cipher 18 ?Sultan wants to generate a message digest of a 2,048-byte message and send to AbdulAziz. If Sultanconsiders the SHA-1 algorithm, what will be size of the message digest bits 160 O bits 512 O bits 1,024 O bits 2,048