JVCL Help:TJvVigenereCipher

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Class Hierarchy

TJvCustomCipher
TJvVigenereCipher
run\JvCipher.pas


Summary

A component that encodes and decodes according to the Vigenere cipher method

run\JvCipher.pas


Pascal

 run\JvCipher.pas
 TJvVigenereCipher = class(TJvCustomCipher);


Description

  1. JVCLInfo

Here is a short explanation of the vigenere cipher, inspired by the much more complete description available at this address: http://www.trincoll.edu/depts/cpsc/cryptography/vigenere.html

For each letter of the Key, a new alphabet is created by shifting the usual alphabet to start at the same letter as in the key. For instance, if the key is CUP then three alphabets are created:

CDEFGHIJKLMNOPQRSTUVWXYZAB
UVWXYZABCDEFGHIJKLMNOPQRST
PQRSTUVWXYZABCDEFGHIJKLMNO 

When encoding a string, each alphabet is used in turn as a lookup table. For instance, if we encode HELLO, then we have this:

H --> J

E --> Y L --> A L --> N

O --> I

As you can see, the same letter is not always encoded by the same letter, thus making statistical analysis a bit harder. The implementation in this component considers an alphabet of 255 characters, thus encoding every single character no matter what its value is.

run\JvCipher.pas


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run\JvCipher.pas



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