[majke]

Assuming a candidate without super-strong experience:

1) Good code sample showing non-trivial piece of code, ideally in C. (craftsmanship)

2) Reasonable github profile, showing ability to contribute to some opensource projects (which means: basic git skills, communication skills, testing) (craftsmanship)

3) Reasonable experience from CV (assuming we're not talking about hiring for junior role) (craftsmanship)

4) Genuine interest and experience in one of crypto or security or networking. (depth)

5) Debugging skills. Systemtap? Valgrind? (depth)

6) Basic understanding of different programming paradigms. Haskell, erlang, scala or prolog count. (breadth)