Ahmed and one of his close friend, Ali, used to send e-mail using public and private key encryption. He can send e-mail to Ali using the following two methods:

1.He encrypts an e-mail with Ali's public key and decrypts it with his own private key.

2.He encrypts an e-mail with his own private key and Ali decrypts it with his public key.

(a)In fact, anyone can have Ahmed's public key and hence can read the e-mail sent out by Him through second method. Why he might still want to use second method? (2 mark)

Briefly describe and suggest a method of using public and private key encryption which would be better than first and Second method for allowing Ali to read e-mail sent by Ahmed