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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: Security GatewaysDid somebody attempt to design specialized hardware to do UMAC? Julo Jim McKinney <jmck+@ece.cmu.edu>@ece.cmu.edu on 03-08-2001 21:55:06 Please respond to Jim McKinney <jmck+@ece.cmu.edu> Sent by: owner-ips@ece.cmu.edu To: ips@ece.cmu.edu cc: Subject: RE: Security Gateways Approved: sskm1 > Bernard Aboba wrote: > > Integrity protection via new MACs such as UMAC is *not* > expensive. This is > a myth. See http://www.cs.ucdavis.edu/~rogaway/umac/perf00.html > Bernard, Thanks for the pointer to some current research in this area. That paper gave cycles/byte numbers for their algorithm, on a Pentium III and PowerPC. For now, I'll comment on the PPC numbers, because that family is available as an embeddable core that can be integrated into hardware, while the Pentium III is not. For 1500-byte messages, it looks like UMAC will take between 2.7 and 3.7 CPU clocks per byte (estimates, as no numbers were given for the full UMAC function on PPC). That indicates that I'd have to run my core at 600-800 Mhz to handle a single full duplex Gigabit Ethernet port, assuming I have the packets in memory that's fast enough to not stall the CPU, and that there's some way of getting packets into and out of that memory without interfering with the CPU. I grant you that is "do-able," and it certainly is less expensive than HMAC-SHA1, but I wouldn't call it "cheap." At least for some portion of the audience here, "cheap" may be measured by how many thousands of gates the implementation adds to the existing data path logic, and "fast" by how many gate delays were introduced into that path. So, I guess that puts me in agreement with Jim William's comments; security protocols MUST be supported, and supported in the context of a single standard, not a "de jure" standard and a "de facto" alternative. And, if that means the standard must embrace non-monolithic "system level" compliance, then let's figure out how to do that properly, rather than declaring it illegal and hoping it will go away. - milan
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