Vigenere Cipher C++ implementation

Simple implementation of basic file encryption and decryption using the Vigenere algorithm.

After running the build and choosing the operation you will be required to pass 3 values:

• inputPath - an absolute path to a file containing values for transform

• outputPath - an absolute path to a file where your result will be stored

• keyword - mandatory string used for calculating the char position in the alphabet, this value is needed to perform both the encryption and decryption - eg. test

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note: double slash - \\ - is only required on windows, you can use a single slash in the unix based operating system

How does it work ?

Encryption and Decryption

To encrypt a character the position of the sign is evaluated based on the current key character and current word character

In the example above you can see that we treat both word chars index as a position of a final character, so for this case the index of M is our xOffset and index of H is our yOffset and we find a character that's located at the x, y coordinates.

To decrypt the character we basically treat the encrypted char index as our xOffset value and subtract the yOffset from it to revert the ecryption operation

Changing file content

To output the converted value to a new file the code iterates through all lines of the inputPath file. The Vigenere Cipher transformLine method is called for each line and a new converted line is returned as a result.