NETWORK SECURITY AND CRYPTOGRAPHY

ABSTRACT

For the first few decades of the existence of the computer networks, they were primarily used for email and for sharing printers. Under these conditions, security did not get a lot of attention. But now, as millions of ordinary citizens are using networks for banking, business dealings, military etc.., network security is looming on the horizon as a potentially massive problem. Most security problems are intentionally caused by malicious people trying to gain some benefit or harm someone.

Many methods like firewalls, VPN, authentication, encryption and cryptography have been devised to provide proper security strategy. Among all these methods, the most secured method is cryptography. Cryptography is the process of converting the message into coded language (encryption). The breaking of the coded message is called decryption. Cryptography covers the areas of authentication and encryption.
Cryptography includes methods like code and code books, steganography and ciphers. Ciphers play the key role in cryptography. Symmetric cipher consists of a key called secret key used for both encryption and decryption. Asymmetric cipher consists of keys called public key (non-secret key) and private key (secret key). Substitution and transposition are the two methods of encryption. Substitution is the method of replacing the original letter with the duplicate. Transposition is the rearrangement of the given plain-text.
Encrypting the message deals with many algorithms like DES, AES, RSA, MD5, SHA-1,etc...
DES is a secret key algorithm. RSA is a public key algorithm. Algorithms like DES, RSA cannot shorten the long length messages. The solution is to digest the messages using a hash function. The two most common hash functions are called MD5 and SHA-1. MD5 is ideal for authentication purposes. MD5 algorithm produces 128-bit message digest output. It is slightly faster than SHA-1. Thus without proper network security, whatever may be the developments in the networks, we cannot efficiently utilize the benefits.