Date: Thu, 13 Oct 2005 17:08:45 +0200 (CEST) From: sebastian.rother@...erlin.de To: john-users@...ts.openwall.com Subject: Re: Using Hardwareaccelerators to speed up John > Sebastian, > > I'll add a few more comments to my response, please see inline: > > On Thu, Oct 13, 2005 at 06:33:49AM +0400, Solar Designer wrote: >> The current implementation of the MD5-based crypt(3) in John (that does >> not yet use MMX/SSE/AltiVec and the like, -- great speedups are possible >> here!) achieves 5k c/s on a typical Pentium 4 processor (and up to 10k >> c/s on the fastest ones available). The 5k c/s correspond to 5 million >> invocations of the MD5 compression function a second, plus a lot of >> "high level" overhead. The compression function takes a 64-byte data >> block and a 16-byte vector as its input, and produces another 16-byte >> vector as its output. That's 96 bytes of data to transfer per >> invocation. (In practice, it is likely that a crypto card would not >> offer the compression function on its own, resulting in more overhead.) >> Ignoring any protocol overhead, that would amount to 480 Mbytes/second >> of data transfer to/from the card. That's almost 4 times the PCI >> bandwidth. Of course, faster buses do exist, but didn't we want an >> economical solution and also one allowing to use multiple cards in a >> system (with all sharing the same bus)? > > FWIW, the particular crypto card you've been referring to: > > http://www.soekris.com/vpn1461.htm > > can only do 720 Mbps at MD5. This barely fits in regular PCI, but it is > several times slower than what John currently achieves on typical CPUs: > > 5000 c/s * 1000 * 64 * 8 / 10**6 = 2.5 Gbps at MD5 > >> > Offen you'll find just some realy lame Chips on VPN-Hardware but if >> you >> > don#t buy such a Cisco-Junk solution you could also get such a device >> here >> > (not sold yet): >> > >> > http://www.soekris.com/vpn1461.htm >> > >> > This card could, depends to the algorithm, do e.g. up to 920Mbps of >> DES. > > Having reviewed this URL, I think that the 920 Mbps might correspond to > RC4 and not DES, although I do not rule out the possibility that it > actually refers to both of them. > >> Now this is not that bad, however, John already achieves better than >> that on modern CPUs. In particular, it achieves 1M c/s for traditional >> crypt(3) on PPC G5 1.8 GHz or P4 3.6 GHz (the latter with non-public SSE >> code, I must admit). This roughly corresponds to 1.6 Gbps at DES. >> PPC G5 2.7 GHz does over 1.6M c/s, which roughly corresponds to 2.5 Gbps >> at DES. >> >> More importantly, please see above for why this rate likely does not >> apply to password cracking. > > Please don't get me wrong, -- these cards are very good for their > intended purpose. Their performance is in fact very impressive for > their low power consumption. > > They're just not good at password cracking. > > -- > Alexander Peslyak <solar at openwall.com> > GPG key ID: B35D3598 fp: 6429 0D7E F130 C13E C929 6447 73C3 A290 B35D > 3598 > http://www.openwall.com - bringing security into open computing > environments > > Was I helpful? Please give your feedback here: > http://rate.affero.net/solar Ok I understand your arguments. I guess Soekris is a nice company and "maybe" they'll develop a Card useable for john. So if a "normal" CPU is normaly faster: What's about SMP? John does not use more then 1 CPU at the moment so if a normal CPU works (mostly) much better then a Crypto-Card why doesn't john support this function? :-) Kind regards, Sebastian -- Don't buy anything from YeongYang. Their Computercases are expensiv, they WTX-powersuplies start burning and their support refuse any RMA even there's still some warenty.
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