To fulfill the above objectives the following formats of cryptography are practiced- Symmetric cryptography- also known as secret key cryptography, it is a method in which both sender and receiver share the same secret code and key for encryption and decryption.

This technique is useful if you are communicating with a limited number of people, however, it is not much useful for mass communication. Asymmetric cryptography- this is also known as public key cryptography in which, separate keys are used for encryption and decryption. This is useful for key exchange and digital signatures such as RSA, digital signature algorithm, public-key cryptography standard etc.