I need to write something like this anyway. I'll work on it tonight, and send it to you tomorrow.
John
On Thursday, October 17, 2002, at 04:30 PM, Richard Levitte - VMS Whacker wrote:
In message <[EMAIL PROTECTED]> on Thu, 17 Oct 2002 16:19:23 -0400, John Viega <[EMAIL PROTECTED]> said:
viega> > viega> Also, why isn't counter mode implemented in a generic fashion?
viega> > It's
viega> > viega> so simple, it should be usable with any block cipher without
viega> > having to
viega> > viega> write additional code.
viega> >
viega> > Ask yourself why OFB, CFB, CBC and ECB modes aren't implemented
viega> > generically. A hint: speed. Someone made a test having a generic CBC
viega> > that would take a pointer to the cipher function to use. The speed
viega> > apparently decreased enough for it to be an issue.
viega>
viega> I mean have a generic implementation, not necessarily a generic
viega> interface. I was more thinking a counter mode macro that could be used
viega> to create counter mode instances for all block ciphers quickly.
That's something I've thought of just a few days ago. I'll add that
to my TODO.
viega> Additionally, if you were to create a COUNTER wrapper along the lines
viega> of the HMAC wrapper (clearly it'd need to be a bit different), you
viega> wouldn't need the indirection of a function pointer whatsoever, and
viega> would not need to explicitly instantiate macros.
All the HMAC stuff I see (quick look) call EVP functions. If the mode
functions did that, we'd see dramatic slowdown. Not a good thought.
--
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