I have a friend with that attitude. It's led him to implementing his own encryption libraries, UI libraries and so forth, and... Well, I have to admit he's sma

I have a friend with that attitude. It's led him to implementing his own encryption libraries, UI libraries and so forth, and... Well, I have to admit he's smart, but the software he writes outside of work is some of the worst I've ever used. Furthermore, I was able to crack his RSA implementation with a straightforward timing attack. Some things shouldn't be reimplemented. Perhaps he could have implemented them, then used something else? True, but that's a hard sell.