[Petrushka]

I'll agree I could be a little less demeaning. The point is though that cryptography more then anything else is about its practicality, and so by ignoring the difficult parts of it you render any statement you make pointless. Also, although you are correct about noting that under infinite resources RSA et al is breakable, again, practicality. If it takes longer then the previous amount of time elapsed in the universe to break (assuming proper implementation etc.) then it is, for all intents and purposes, unbreakable.

[ColinWright]

Do you think that in an article aimed at students that's the right place to start? Side-channel attacks, timing attacks, differential analysis, weaknesses in key exchange, why padding is necessary, biases in pseudo-random number generation, etc, etc, etc ...

Or is it better to start with what crypto is, with key generation, encryption, decryption, then move on into the first level of complexity?

[betterunix]

For what it's worth, practical secure cryptosystems only exist under a number of assumptions that, thus far, have no proof. Commonly used public-key systems are in an even more precarious position: even if P!=NP, the RSA and discrete logarithm problems may still be computationally feasible (and thus RSA, Diffie-Hellman, and ElGamal would be insecure). Cryptography based on NP-hard problems is possible (e.g. Atjai's lattice system), but these remain research topics and have seen little real-world use.

The point is this: there is a lot we do not know about cryptography.