Communications and Security - Past, Present, Future

The need for communication is very ancient. It includes being able to communicate over long distances without being eavesdropped. This is where security for communication comes in.

Julius Caeser  used a unique (for his time) method of encrypting his messages. He used what is today known as the Caeser Cipher.

Caeser cipher is a simple substitution type of encryption method in which the encrypting as well as the decrypting key is the alphabet shifted by a certain number of places(either backwards or forward). So if the key was the English alphabet shifted backwards by 3 places then every 'a' in the original message would be replaced with a 'x'.

Example - Original Message - " How do you do "
 Encrypted message- " ELT AL VLR AL "

The encrypted message will in itself be completely useless even if had been opened by unauthorized people.

The need for security while communicating is still paramount and in recent times even gained more importance. The importance of this can be gauged from the following.

During the Second World War the Germans had the engima machine which they used to communicate with each other. The British had broken this code by 1940 and used this to their advantage. The Germans eventually lost.

Since then encryption for communications has come a long way and can be divided into two major parts
1. Symmetric encryption
2. Asymmetric encryption

We will have a look at both of these briefly -

1. Symmetric encryption - In this type of encryption both the parties use the same key to encrypt and decrypt messages. These keys are decided using the Diffie - Hellman protocol. Example of such type of protocols are AES encryption, DES, Triple DES etc

2. Asymmetric encryption (Public key encryption) - In Asymmetric encryption in general there are two different keys which are used. For example in RSA there are two keys, a public key and a private key. The private key is kept secure by the server which uses this key to encrypt as well as decrypt messages while all other people who wish to communicate with the server need to use the public key to encrypt and decrypt data.

Asymmetric encryption

The major difference between the two is that Asymmetric encryption or Public key encryption is costly in terms of computation as compared to symmetric key encryption.

Security in communications is here to stay and will continue to be important. As technology develops and computation power increases it will be easier to break existing protocols and hence there will be a need to come up with new protocol which will be more secure and attuned to the surrounding technology. The race between the good guys and bad guys is on. I'm happy so long as the good guys are one step ahead of the bad guys !!