[RC5] blocksize suggestion
swasson at arrowpoint.com
Wed Jan 13 14:34:07 EST 1999
>Steve Bird (sbird at UATC.com) wrote:
>Blocksize is irrelevant. I'm leaving mine at 2^31. I'll set my buffer to
>handle as many blocks as I can compute in 1 hour and let it roll. SO
>technically, if I do find the key, I could cause d.net to waste its time
>for an hour. But, to be perfectly honest, I don't think they'll mind.
The main concern is keeping the system busy for ~12 hours (I dial in about
twice a day), without hoarding blocks. If the preferred blocksize is set
to 31, and I set input buffers to 20, then I *might* get 8*20=160 blocks,
right? That would be just about right for my system without excessive
The problem is, though, it's only a preferred blocksize. I might get as
many as 160 blocks. But then again I might get all 2^28 blocks, for a
total of only 20 blocks. :-( You just don't know what you're going to get.
To circumvent this, I do one of two things, depending on which test is
1. When RC5 is running, I set preferred blocksize to 31, and RC5 input
blocks to 100. There's no way of running out of work any time soon, and
hoarding RC5 blocks is a non-issue.
2. When I hear that a DES contest is about to start, I reduce the preferred
blocksize to 28 so that I get a very deterministic number of DES blocks. I
have DES input set to 160, which I know takes about 10 hours to process.
This way I'm not forced to hoard excessively in order to guarantee that I
It just would be nice if this reduction to 28 could happen automatically.
-Scott Wasson, ArrowPoint Communications
-swasson at arrowpoint.com
-(978) 692-5875 x530
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