Seriously, I'd advise that you implement an HMAC today, and implement GCM tomorrow — using raw CTR mode really is that dangerous. And make sure that you never

Seriously, I'd advise that you implement an HMAC today, and implement GCM tomorrow — using raw CTR mode really is that dangerous. And make sure that you never ever ever reuse IVs, ever. This sort of thing is incredibly dangerous. Props to you for coming up with a great UX, but crypto is very, very difficult to get right.