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Network Security: What is Cryptography?

written by: Ashwin Satyanarayana•edited by: Ronda Bowen•updated: 7/4/2011

Do you like solving puzzles? Well, most of the puzzles out there are made such that can be solved. What if you made one that cannot be solved? Well, what if it is difficult to do so? Enter the world of cryptography which deals with a lot of things secretive. What is Cryptography? How does it work?

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    Cryptography is derived from a rough Greek translation for “Secret Writing”. Cryptography is all about mangling information into a block of characters that apparently don’t make any sense. However, all of this mangled information can be unmangled by deploying some secret methods.

    Cryptography is very useful from an IT company or an IT user’s point of view because it provides for the following:

    • Enhanced Security: Cryptography is now the standard protocol to deploy enhanced security levels in anything that has “digital” written all over it. Increased business dependence on email correspondence and internet has led to an insatiable need for sustaining methodologies that use Cryptography.
    • Integrity Checks: Using cryptography, tremendous amount of reassurance is possible for the recipients because they would have a way to find out if the incoming message has been tampered with in any way. It enables to find out if the message is coming from a legitimate source.
    • Authentication: As first line of defense, cryptography is increasingly used for authentication purposes which, in effect, help to verify the identity of someone or something.

    The original message that is intended for cryptography to be applied on (to be encrypted) is called as “plaintext” or “cleartext”. The process of changing into unintelligible blocks of characters is called encryption and the process of turning it back into “plaintext” is called “decryption” (this is the reverse of encryption).

    The people who are able to do all of this encryption are called cryptographers and they have a formidable opposing camp called as cryptanalysts (whose expertise is decryption). These opposing camps are forever at logger ahead and are trying to outdo each other.

    An Algorithm and a secret value is always an integral part of the Cryptographic systems. This secret value is called as a “key”. For a said system, an algorithm is devised once and the knowledge is made public. However, all message transmission is encrypted or decrypted using the key that is unique for each user. Just knowing how an algorithm works isn’t going to help anyone decrypt with the key which only the person holding it would know.

    Think of the entire cryptographic system as a combination lock. You know how combination locks are made, don't you? When you purchase a lock, you are allowed to set your own combination which would allow you access to whatever it is that is being locked up.