Complexity Theory - Cryptograp
One important, yet practical, application of complexity theory is cryptography. It has become one of the main tools for privacy, trust, electronic payments, and other forms of security. It is no longer just a military tool and the advantages it provides should be used to the fullest extent. This paper will discuss basic terminology and popular methods of cryptography. Cryptography is the science of scrambling text so that no one can read it except for the intended recipient. The art of breaking ciphers without the proper key is called cryptanalysis. Cryptography deals with the secure message, digital signatures, authentication, and other similar applications. Cryptology is the branch of mathematics that studies the foundation of cryptographic methods. The process of transforming plaintext into a form that is meaningless to anyone that might intercept it is called encryption. The process of decoding the message is called decryption. This can be done by using an encryption algorithm, a decryption algorithm, and a secret or private key. The sender uses the encryption algorithm to encode the message, and the receiver uses the decryption algorithm and
Theoretically, it is possible to break any cryptographic method that contains a key, simply by trying all of the keys in sequence. With the use of brute force to try all keys, the required computing power would exponentially increase with the length of the key. The longer the key, the longer it will take to break the key. A 32 bit key takes 232 steps. Today, this can be done easily on a typical home computer. If an efficient algorithm were used, a 40 bit key would take approximately one week to break on a modern home computer. A 56 bit key (such as used with DES) would take a lot more effort, but a large number of home computers using distributed effort can break it in just a few months. Most keys with 64 bits are breakable by governments, organized criminals, and major companies within a few years. Keys with 80 bits appear to be secure for a few more years, and 128 bit keys should remain unbreakable by brute force for the foreseeable future, ergo Microsoft'sc recent upgrade to 128 bit encryption. 3. Non-repudiation; the creator cannot deny at a later stage his intention in the creation and transmission of the information. Sir Francis Bacon's biliteral cipher employed an arrangement of the alphabetic letters 'a' and 'b' in five-letter combinations each representing a letter of the alphabet. This illustrates the principle that a code employing only two different signs can be used to transmit data. 5. Letter frequency analysis: In normal text, some letters, like "e", appear more often
Some common words found in the essay are:
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Approximate Word count = 3439
Approximate Pages = 14 (250 words per page double spaced)
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