RSA

RSA is an algorithm used to encrypt and decrypt messages.  The algorithm uses public and private keys along with modular arithmetic and prime factorization to make this type of encryption impossible to decode with large numbers.

The image below walks you through what an encryption and decryption would look like between two parties; Salt and Pepper, passing the message "STOP".

It might also be helpful to review the "Introduction to RSA" videos with Khan Academy

How to Use the App

1. Open the file RSA.ipynb in an environment that supports IPython Notebook.
2. Follow along each of the cells to become familiar with each function. -OR-
3. Skip to the main() function in the notebook and start encrypting and decrypting your own messages. Start with GetKeys, then Encode, followed by Decode, copying and pasting your results to save for the next step.
4. Enjoy!

Disclaimer

In this implementation letters are not grouped together for the encryption, as shown in the Salt and Pepper example pictured above. Instead each letter is given it's own encryption. This would make the codes easier to decrypt if one had the public keys. All they would need to do is find the prime factorization, i.e. the two prime numbers used in step 1 of the Salt and Pepper example. In real world implementations of RSA, letters are grouped together during the encryption process making it impossible to find the prime factorization and decrypt messages.