gapcrypt refences

http://en.wikipedia.org/wiki/RSA_%28cryptosystem%29#A_worked_example
http://en.wikipedia.org/wiki/Euler%27s_totient_function
http://en.wikipedia.org/wiki/Modular_multiplicative_inverse
http://terrytao.wordpress.com/2014/12/16/long-gaps-between-primes/
http://en.wikipedia.org/wiki/Prime_gap