In 1874 Stanley Jevons realised the existence of trapdoor functions. The multiplications of two primes is a very easy task. But given the product it is very hard to figure out which two primes were used. He stated
"Can the reader say what two numbers multiplied together will produce the number 8616460799? I think it unlikely that anyone but myself will ever know."
However his statement was far too optimistic. Ever is a very long time and advances in science and computer technology make computations possible that were impossible only few years back. Nowadays on my computer it takes almost no time at all to figure out that he used 89681 and 96079.
This case gives us an important warning. Cryptography that we use today may be broken in ten years. Whatever we send public but encrypted may come to light in the future. It is safe now, but not indefinitely. For real security use a few extra bits and a quantum resistant algorithm. But even that may not be enough for a human lifetime.
Nowadays we know much larger primes than in 1874, for example 2^45 - 229. Everyone can build cryptography that will protect data for the moment. But dont assume this is absolute security.
[0, 1, 6] all later giggle praise
