Introduction to cryptography

A brief introduction to cryptography

Modern cryptography offers solutions to problems of an operation network.

Cryptography- If we want to protect sensitive communication we use some kind of code or cipher, replacing the “real” words with code words or shifting characters to hide the real meaning of our messages. Governments and military organizations have always needed to protect their communications.

Objective: keeping the secrets secret.

The whole point of cryptography is to keep information out of hands of anyone but its intended recipient. Even if the message gets intercepted the meaning won’t be apparent to the interceptor unless the interceptor is able to decipher it.

Cryptography uses encryption to transform plain texts into encrypted texts. The idea behind modern encryption methods is to make it so costly in time and resources for an interceptor to interpret a message that is not practical to even attempt it, while keeping it easy for an authorized recipient to read.

Coders and ciphers- A code actually uses some method of interchanging vocabularies so that each code word represents some other non code words. Codes require special code books which act like dictionaries, if the code book is lost, anyone having the code book can read encoded text.

Ciphers are the basis of encryption schemes. Traditional ciphers use a single key, which the sender and recipient share and try to keep secret from anyone else. The sender runs the algorithm using the key to turn the plain text message into an encrypted message and the recipient runs the same algorithm in reverse to decrypt the message. This is known are symmetric cryptography.

Breaking encryption schemes- Cryptographers accept that all ciphers are vulnerable to brute force attacks and they design ciphers with this in mind. The key to security is usually the cipher key size. A cipher key can be compared to a combination lock; if you have a correct key you can unlock the message. But the 3 digit lock is easily traceable.

Increasing the size of the key is important and makes it more secure over a longer period of time.

Data Encryption Standard- One widely distributed secret key solution is DES. The US, National Bureau of Standards published DES in late 1970s for commercial uses. For instance automatic teller machine networks use DES to encrypt consumers’ PINs when they are transmitted through shared network and data communication lines.

DES is considered safe against all but brute force attacks which are considered to be impractical against DES for all but the very largest and most determined organizations. DES can be implemented reasonably efficiently for bulk encryption like that required by electronic commerce applications.