title: Why is public key cryptography used in sites like Google, Facebook (what is the need to encode data in these sites)?
body: <p>The RSA algorithm is used for encryption (plain text to cipher text) and decryption (cipher text to plain text) of data. What is the need for using public keys in these sites; why is data encrypted as everything is viewed by everyone?</p>
  
  <p>Why do we need to use public key cryptography in Google; how does it provide security?</p>