Never roll your own crypto no matter how convenient.
Wait a minute, I support fully what OP is doing here. He seems to be taking an opportunity to dig into the technology and learn about it. Rolling your own __ is the best way to learn about __, imo. Of course, if you're new, you need to be careful, but that's what OP seems to be doing.
I wish I was savvy enough to comment on the particulars of this method/library, but alas...
For learning, yes, but it's easy to introduce a bug into crypto take a look at what happened to blockchain.info. So you shouldn't use stuff you wrote yourself for important purposes unless it's been analyzed and tested by millions of people.