# Symmetric or Private Key Cryptography Seminar

Let’s look at the some of the Network Security and Software Development concepts, before going in to the further processes.

## Cryptography

Cryptography is one of the most important domains in the computer science department. Enigma machine is the widely known application used at the time of World War II by the German military to protect their sensitive communications. This is a technology used to exchange important data securely over a network hidden from eavesdroppers. This is achieved by encrypting the data at the transmission end and decrypting the data by the end user who is the receptor.

Cryptography protects information from theft or alteration and also provides user authentication. Cryptographic schemes are of three types:

• Secret key (or symmetric) cryptography
• Public-key (or asymmetric) cryptography
• Hash functions

The initial unencrypted data is referred to as plaintext and is encrypted into cipher text, which is again decrypted to usable plaintext.

In our project we are implementing both the Cryptographic suites to make use of the advantages they provide.

## Symmetric or Private Key Cryptography

Symmetric key encryption is the process of encrypting and decrypting secret message using a same key, which is distributed to the members whoever is participating in the communication. The strength of the encryption depends on the size of the key used; trivially larger keys are used for encrypting larger blocks of data where it is very difficult to decrypt the data by eavesdropper for those who don’t have the key pair.

The number of keys required to encrypt the data depends on the number of persons communicating. It is given by the formula

Number of keys = [n+ (n-1)]/2.

Symmetric key cryptography is of two types “stream ciphers” and “block Ciphers”. Stream ciphers divide the message into bits and processes individual bits whereas Block ciphers take a number of bits at a time and divide them into blocks of a fixed size and processes them. In general a block of 64 bits has been used for encryption; in the latest versions approved by NIST i.e. Advanced Encryption Standard (AES) a block of 128 bits has been taken.

This Project Paper is written & submitted by Deepak V.