This code was submitted as part of my IB extended essay entitled 'How does RSA work and how secure is it?'. Read the paper here.

RSA

Here's an example usage, from rsa.py.

    #Alice = Reciever, Bob = Sender
    '''ENCRYPTION'''

    #Alice generates keys
    e,d,n = genKeys(100,9999)
    print('public : ',e,n)
    print('private: ',d,n)

    #Bob; public key = (e,n)
    m = 126 #message Bob wants to send Alice. Encrypts using Alice's public key
    c = encrypt(m, e, n) #ciphertext, Bob transmits

    print('\nmessage =', m)
    print('ciphertext =', c)
    
    #Alice; private key = (d,n)
    p = decrypt(c, d, n) #Alice recieves ciphertext and decrypts using her private key
    print('plaintext  =', p)


    '''SIGNING'''
    #Alice: uses same keys (e,d,n)
    data = 986 #Alice wishes to sign data to verify that she sent it
    s = decrypt(data, d, n) #signature; Alice signs using her private key, (d, n)
    #signiture, s, is transmitted along with data

    print('\ndata =', data)
    print('signature =', s)

    #Bob recieves data & signature
    v = encrypt(s, e, n) #Bob encrypts s, to p (using Alice's public key)
    #if (v==data), Bob knows only Alice could have sent the data, and that it has not been altered
    print('verification =', v)