Program File Name: vigenere.py
Author: Tyler S. Budd
Completion Date: 9/12/2019
A modified version of the classic Vigenere Cypher. Instead of using just letters that are confined to uppercase or lowercase, I've allowed it to accept all ASCII characters from 32 [space] to 126 [~]. This gives the message much more security and much harder to crack with human eyes.
At first, I was going to approach the problem by creating the matrix and using the analog "search and find" method, like what we would use in the image below. Instead, I found a better approach to use only mathematics.
For example, if we were to encrypt a message with only the original 26x26 matrix, I would use the formula:
- Encryption(i) = (Plaintext(i) + Key(i)) mod 26
- i = index of the string
To decode, I use the formula:
- Decryption(i) = (Encryption(i) - Key(i) + 26) mod 26
- i = index of the string
Because I used 94 ASCII characters as my matrix, I modified the formulas.
Welcome to the Vigenere Cypher Program!
Created by: TYLER S. BUDD
Creation date: September 12th, 2021
NOTE: This encryption program only encrypts/decrypts letters, numbers, and basic punctuation.
Any symbol/letter not found on a US keyboard will result in failure.
To ENCRYPT a message, type 'encrypt' and press ENTER
To DECRYPT a message, type 'decrypt' and press ENTER
Selection: encrypt
COPY/PASTE or TYPE plaintext message here and press ENTER: this is a test
Type in the key phrase to encrypt and press ENTER: holiday
Encrypted Message: ^RS]hS]hKh^O]^
To close the program press Ctrl+C
Copy the encrypted message: ^RS]hS]hKh^O]^
Restart the program
Welcome to the Vigenere Cypher Program!
Created by: TYLER S. BUDD
Creation date: September 12th, 2021
NOTE: This encryption program only encrypts/decrypts letters, numbers, and basic punctuation.
Any symbol/letter not found on a US keyboard will result in failure.
To ENCRYPT a message, type 'encrypt' and press ENTER
To DECRYPT a message, type 'decrypt' and press ENTER
Selection: decrypt
COPY/PASTE or TYPE encrypted message here and press ENTER: ^RS]hS]hKh^O]^
Type in the key phrase to decrypt and press ENTER: holiday
Decrypted Message: this is a test
To close the program press Ctrl+C
94x94 ASCII matrix used available on the file vigenereCypherMatrix.txt
Original 26x26 Matrix and encoding example: 
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