RSA Cryptosystem

Encrypts and decrypts messages using RSA.

First, enter lower and upper limit for primes, which will then be generated randomly, depending on given interall. Public and private key will be compted. Enter the message to be encrypted and confirm. Message will then be encrypted using parameters computed earlier.
Note: This function only serves as demonstration of the "real" algorithm, using an intervall bigger than 10^4 is not recommended.