[bug, enhancement] Prime inconsistance

[arthurvergacas]

I was reading your article, and then decided to check this code! everything worked nice, but sometimes I experienced some weird issues happening with the decryption. After some debugging, I found that low or equal primes (such as 3 and 2, or 13 and 13) caused this issue.

I've already made a pull request for you :), with some other stuff that I specify in the PR description.

Here's the PR: #2

Cheers! 😄