What is symmetric key encryption? Compare symmetric and asymmetric encryption with examples.

What are the differences between message confidentiality and message integrity? Can you have one without another? Use the additive cipher with k = 5 to encrypt the plaintext "BU". Then decrypt the message to get the original plaintext.

 What is RSA algorithm? Alice wants to send message a to Bob. Then Bob need to select keys. Suppose, Bob chosen p = 7 and q = 13 in the RSA algorithm. Now, find the value of d. Also, encrypt the message "CSE" using Bob's public key so that he can only decrypt. For simplicity, do the encryption and decryption character by character.

Alice uses a mobile app to hide messages in image pixels. Is this encryption or steganography? Explain.