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Old 2009-06-23, 16:19   #11
lavalamp
 
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Oct 2007
London, UK

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Rainbow tables are good for alphanumeric passwords up to 8 chars in length, and some other types of password that are longer (all lower or all upper case, numeric etc.). Even with a salt, these can be recomputed.

And currently it seems that 200 PS3s in 3 days can find a specific string to match a hash (or 100 in 6 days, 50 in 12 etc.), tomorrows hardware will bring this within reasonable limits, and more and more progress is made in destroying MD5 every day. SHA-1 isn't far behind.

If that isn't a significant and practical break then I don't know what is. If you question the word "practical" there, consider just how many GFLOP/s users here throw at prime finding, or ask yourself what the thousands of members of the more militant wing of Anonymous might be able to do by only gaining read access to a websites database user table, or whether the RIAA and/or MPAA will be poisoning popular torrents they don't like with slightly altered pieces to corrupt the data, heck Microsoft could even do that for Linux torrent downloads.

So my main point remains, why bother with MD5 now? It's blatantly risky and there are far stronger hash functions available.

Edit: I should point out that although I don't know if the researchers used the graphics cards in the PS3s or just the cell CPUs, if it was just the cell CPUs then my graphics card is 12 times more powerful, 2.4 TFLOP/s to 0.2 TFLOP/s. The graphics cards in the PS3s can apparently bench press 1.8 TFLOP/s. This is all in single precision of course.

Last fiddled with by lavalamp on 2009-06-23 at 16:44
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