Cryptography


is the science of encoding a message into a form that is unreadable and making sure only the proper people are capable of decoding the message back into its original form. This is usually done by using an encryption algorithm and a decryption algorithm (these two are often the same) and very often a secret key. Some of the early cryptographic systems did not use a key but instead kept the algorithm itself secret. The message sender uses the encryption algorithm and the key to encode the message, and then sends it to the receiver. The receiver then uses the decryption algorithm and the key to turn back the encrypted message into its original form and read it.
If the message is intercepted ...

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and could only be decoded using special staff keys. The key actually consisted of a physical object, which was applied on the message to get the decrypted version of it. In 50 Bc., one of the most simple cryptographic algorithms ever used was the one called the Caesar cipher, that was used by Julius Caesar to send messages to his generals. It consisted simply of switching each letter with the letter that was 3 letters further down the alphabet.
For example "Stephen" would become "Vwhskhq". To decrypt the message, the receivers would simply subtract 3 letters from each letter. This algorithm was later improved and called ROT13, where the letters could be shifted to any number between 1 and 25, and the number of letters shifted was the secret key. This very simple algorithm has been used on Usenet successfully to prevent people from inadvertently reading materials they might find offensive.
Monoalphabetic substitution is another simple step away from the ROT13 algorithm. In ...

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developed by the Allies, the key, like in the Vigenere cipher, is based on a little table and a short keyword, which were both changed periodically. The rules used with the table were much more complex and made it fairly safe.

In World War II, however, the Germans gave up on abstract algorithms and came up with a physical encrypting/decrypting machine called the Enigma. It had different wheels of different sizes which were to be tuned differently depending on the date, the different turnings were listed in a little booklet that came with the machine. It wasn't broken before the Allies finally managed to capture enough pieces of the machine and collect enough data from operating ...

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"Cryptography." Essayworld.com. December 15, 2005. Accessed May 23, 2018. http://www.essayworld.com/essays/Cryptography/38010.
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PAPER DETAILS
Added: 12/15/2005 12:59:15 AM
Category: Technology
Type: Premium Paper
Words: 3143
Pages: 12

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