One of the main objectives of information security is protecting the confidentiality of the data. In a web application, the aim is to ensure that the data exchanged between the user and the application is secure and hidden from any third party. The data, when stored at the server also needs to be secured from hackers. Cryptography is used to protect the confidentiality as well as the integrity of data.

Encryption is the most widely accepted form of cryptography that is used to protect information. It is used to protect sensitive data against threats like sniffing or data being altered during storage and transmission. When the data flows on the network unencrypted, the attacker can tap in and sniff the data. If the sniffed data contains the authentication credentials, the attacker can hijack the session. Hence, we need encryption. When the data is encrypted, the plaintext is converted into cipher text, which can only be decrypted with the help of a secret...