> ok, sorry for my strictness...
>
> I need create some codes with fixed lenght with deny of ability of other
> people to create such identifiers...
>
> Something similar to phone cards with ID, which I must enter into phone
> before I dial phone number and going to talk...
>
> The code should be
Well, I was confused about how you were confused. I guess you're
saying the HMAC makes 32 printable characters, and this would be
because it is being translated fron binary into hex. What I was
trying to say is that if the hash makes k binary output bits,
it is easy to fold them together with som
