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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