!!! Overview [1]
[Cryptography|http://en.wikipedia.org/wiki/Cryptography] (or cryptology; from Greek κρυπτός, kryptos, "hidden, secret"; and γράφω, gráphō, "I write", or -λογία, -logia, respectively) s the practice and study of techniques for secure communication in the presence of third parties (called adversaries)

!! The story
We often see and use [{$pagename}] where the desire is for [Alice] to send a [Message] to [Bob] in presence of (the adversaries) [Eve] and [Mallory].


is the practice and study of hiding information. In modern times, cryptography is considered a branch of both mathematics and computer science, and is affiliated closely with information theory, computer security, and engineering. Cryptography is used in applications present in technologically advanced societies; examples include the security of ATM cards, computer passwords, and electronic commerce, which all depend on cryptography.[1]

In [{$pagename}] discussions we typically make a [Computational Hardness Assumption].

!! [Cryptography Objectives]
There are some differing opinions on [Cryptography Objectives]

!! [{$pagename}] and [Security]
"''[Security] is only as strong as the weakest link, and the mathematics of [{$pagename}] is almost never the weakest link. The fundamentals of [{$pagename}] are important, but far more important is how those fundamentals are [implemented|Implementation] and used. Arguing about whether a key should be 112 bits or 128 bits long is rather like pounding a huge stake into the ground and hoping the [attacker] runs right into it. You can argue whether the stake should be a mile or a mile-and-a-half high, but the [attacker] is simply going to walk around the stake. [Security] is a broad stockade: it’s the things around the cryptography that make the cryptography effective. ''" - Preface to Practical Cryptography (the 1st Edition) 

!! Major Types of [{$pagename}]
* [Symmetric Key Cryptography] - When using [Symmetric Key Cryptography] all parties [MUST] [trust] each other, because they can read each other's messages.
* [Asymmetric Key Cryptography] - each participant possesses a private and a public key. 
* [hybrid cryptosystem] - 
!! Cryptographic Systems
Cryptographic Systems are what provide [{$pagename}]. Taking any [Cryptographic Primitive] or isolated [{$pagename}] piece will not allow meeting the objectives. Most breaches are caused by a [Cryptographically Weak]ness that has been introduced in the Cryptographic process, often by improper implementation.

!! [Cryptographic Hash Functions|Cryptographic Hash Function]
A [Cryptographic Hash Function] or [Message Digest|Message-Digest] is the output of a [Secure Hash Algorithm] which permeates a source message of variable length into a highly unique, fixed-length [digital fingerprint (signature)|http://en.wikipedia.org/wiki/Digital_signature]. [Cryptographic Hash Functions|Cryptographic Hash Function] cannot be used to reconstitute the original message but can be used by one participant to prove that another participant possesses some secret material (for example, a password). This proof can then be used to establish an identity.

!! More Information
There might be more information for this subject on one of the following:
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* [#1] - [Cryptography|Wikipedia:http://en.wikipedia.org/wiki/Cryptography|target='_blank'] - based on information obtained 2013-04-10