Cryptography. Essay

1347 WordsApr 17, 20116 Pages
Cryptography. (or cryptology; from Greek κρυπτός, kryptos, "hidden, secret"; and γράφειν, gráphin, "writing", or -λογία, -logia, "study", respectively)[1] is the practice and study of hiding information. Modern cryptography intersects the disciplines of mathematics, computer science, and electrical engineering. Applications of cryptography include ATM cards, computer passwords, and electronic commerce. Cryptology prior to the modern age was almost synonymous with encryption, the conversion of information from a readable state to apparent nonsense. The sender retained the ability to decrypt the information and therefore avoid unwanted persons being able to read it. Since WWI and the advent of the computer, the methods used to carry out cryptology have become increasingly complex and its application more widespread. Modern cryptography follows a strongly scientific approach, and designs cryptographic algorithms around computational hardness assumptions, making such algorithms hard to break by an adversary. Such systems are not unbreakable in theory but it is infeasible to do so by any practical means. These schemes are therefore computationally secure. There exist information-theoretically secure schemes that provably cannot be broken--an example is the one-time pad--but these schemes are more difficult to implement than the theoretically breakable but computationally secure mechanisms. Cryptology-related technology has raised a number of legal issues, some of which remain unresolved. Terminology Until modern times cryptography referred almost exclusively to encryption, which is the process of converting ordinary information (called plaintext) into unintelligible gibberish (called ciphertext).[2] Decryption is the reverse, in other words, moving from the unintelligible ciphertext back to plaintext. A cipher (or cypher) is a pair of algorithms that create

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