zahiryahya1 / encryption-decryption

Implemented a list of common cryptography methods to encode messages

encryption-decryption

overview:

Implemented a list of common cryptography methods to encode messages. These methods range from a simple alphabet shift, to more complex modular arithmetic. This program implements Euclidean Algorithm to check relatively prime, find GCD, and mod inverse.

A video demo can be found here: https://www.youtube.com/watch?v=sdLhdzQcasU

ciphers:

1. ceaser cipher - basic

choose a number 0-25 (if larger, then mod 26) and shift the alphabet by that many letters.

ie. abcde...xyz (shift 3)
    defgh...abc 

2. Vigenere - advance ceaser cipher

choose a key word that will shift each letter of the word with its acociated letter.
ie. key: key ---> 10,4,24,10,04
  text: hello --> 07,4,11,11,14, 
  code: rijvs --> 17,8,15,21,18

3. RSA - advance (not good for messages. better for encoding a key for a different encryption algorithm)

a. choose 2 prime numbers b. compute n =qp c. phi = (q-1)(p-1) d. choose e such that gcd(e, phi) = 1 e. compute d: d = e^-1 mod phi d. converte message into an integer e. encrypt: code = message^e (mod phi) d. decrypt: message = code^d (mod phi)

Bugs/Known Issues:

RSA

• case: p = 1, q = 2 does not work.
• 'e' can be 1

Ceaser cypher:

• none

Vigenère cipher:

• none