Cryptography – Revisited

Jun.18, 2008 in Cryptography

Cryptography, or cryptology, derived from the Greek words for “hidden” writing or speaking, is the practice and study of hiding information.

Until modern times, cryptography referred almost exclusively to encryption, the process of converting ordinary information (plain text) into unintelligible gibberish (confidentiality). Cryptography is now considered to be a branch of both mathematics and computer science, and is closely related to the study of information theory, computer security, and engineering. Now we apply this technology to achieve the other two objectives – integrity (using a digital signature) and availability (protecting the data from being corrupted and destroyed).

The key, a parameter that determines the functional output of a cryptographic algorithm, is the important element of cryptography. In encryption, a key specifies the particular transformation of plaintext into ciphertext (or vice versa during decryption).

This concept was introduced in cryptography in 1466 by Leon Battista Alberti, the famous Italian Renaissance architect.

Let’s consider a parallel situation in the physical world to describe how a key works in cryptography. Your own front door lock is mass produced by a company, and each lock is sold with a unique key that works only with the door locking mechanism within the door lock that it is designed for. Other people may own the same lock model made by the company, with the same basic locking mechanism. However, you are the only one who can unlock the door because your key, which is different from the keys of other people, is the only one in the world that fits the specific combination design inside of your door lock, making your home secure (theoretically!).

Computer security works in a similar way. A key used to “unlock” a cryptographic algorithm. And the longer the key, the more difficult it is to break into the system by trial and error. The hacking technique of attempting to break a cryptographic algorithm by trial and error is called a brute force attack, and the time and effort needed to break the system is called the work factor.

For more information about cryptography, refer to various posts in the blog found here:

http://www.bestinternetsecurity.net/category/cryptography/

Tags: Cryptographic Key

Tags: availability, ciphertext, confidentiality, Cryptographic Key, Cryptography, cryptology, decryption, encryption, integrity, Leon Battista Alberti, work factor

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Cryptography – Revisited

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