Search This Blog

Tuesday, August 12, 2008

What is Cryptography


Cryptography is a centuries-old method of communicating sensitive information between two parties in such a way that a third party is restricted from obtaining it. For example, Rose and Fred need to communicate sensitive information. Rose uses an algorithm, called a cipher, to convert the message into unintelligible cipher text (encryption), which can then be sent through an open channel. Fred receives the message and must apply a matching cipher to convert the message back into plain text (decryption). The ciphers are controlled by a set of parameters, called a key. The key is a tool used to encrypt and decrypt. Both parties, Fred and Rose, must have a key.


There are two types of Cryptography, Public Key Cryptography and Private Key Cryptography. The method in which the keys are distributed is the differentiator. The simplest and the most ancient form of key sharing uses private keys. Private Key Cryptography uses identical keys for encryption and decryption. Rose takes a message, puts it in a safe box, locks it with a key, and ships the box to Fred. Fred uses the same key to unlock the message.

The issue is that two keys are needed in separate locations. Frequent and reliable key distribution is needed with this type of cryptography. If the key were compromised, it would be difficult to replace. Public Key Cryptography was ushered into existence by the computer age. With this method, different keys are used for encryption and decryption. Encryption is done with a publicly announced key, which encrypts with bits. Today, 128 bit encryption is being used. Decryption is completed using a private key, which is not shared. The idea is that individuals looking to receive encrypted messages send out encryption keys publicly, while keeping private keys for themselves. The secrecy of the keys relies on computational complexity of certain hard mathematical problems. However, mathematics is constantly advancing. Someone could develop an algorithm that could break or solve the current mathematical problem. In addition, eavesdropping on the key is currently not detectable. That means that users do not know if someone is tampering with their keys.

1 comment:

Jimmy Jarred said...

You have created a very nice blog. I read so many article on it and find each of them very informative. Some latest and important concepts are being covered about which I do wanted to learn. Thanks and keep posting.
e signatures