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Re: MD5 versus SHA

 > c) my argument against MD5 in IPv6 is that the requirements state
 >         that IPv6 should run at least as fast as IPv4.
 >         "At least as fast" presumes the existing hardware;
 >         I can do IPv4 at 75 Mbps with no real effort, and 120 Mbps
 >         with some effort (i.e., user-level protocols sharing a
 >         kernel-based port). 
 >         That's in software on the existing hardware.
 >         If I ran IPv6 on the same hardware, it'd have to be
 >         an all-software implementation, which would slow it to
 >         around 40 Mbps.

I am somewhat familiar with the IPv6 requirements. The intent of the
text is that, everything else being equal, the two protocols should
be roughly the same speed. Now, 40 and 75 are not "roughly the same
speed", true. But everything else is NOT equal. Your note implies
that, for v4 there is some hardware assist, whilst v6 would not
benefit from that assist. It would not be reasonable to expect, and I
imagine that the authors of the v6 requirements document do not
expect, that IPv6 runs 'at least as fast' as v4 when v4 has hardware
assists and v6 does not.

The question to ask is what speeds can be reached with the _same_
level of assist.

Frank Kastenholz    "The dogmas of the quiet past are inadequate to the stormy
                     present... As our case is new, so we must think anew, and
                     act anew" - A. Lincoln