[RC5] old clients and DES-II-1 blocks

Mike Silbersack silby at execpc.com
Sat Jul 11 20:28:50 EDT 1998

On Sat, 11 Jul 1998 14:22:10 +1200, dan carter wrote:

>         What about old DES buffers?
>         A: The 2.7100 clients will identify DES blocks from DES-II-1
>that may be sitting in disk buffers and discard
>         them. The older clients will process them. Theoretically, the
>buffers simply tell the client which part of the
>         keyspace to check, so no harm will come, it will just mean
>your work won't be coordinated by the
>         keyserver which may cause a small amount of duplicated work.
>Perhaps a coder would like to coment on
>         this.
>Is this true, or do the buffers contain something more important like
>the cyphertext?
>If so are the proxies equiped to discard the results of DES-II-1

DES-II-1 blocks ARE different than DES-II-2 blocks, as the
cyphertext/etc is different for each contest.  Here's a rundown of the
handling of des-ii-1 blocks:

2.7100 clients check the cyphertext of each block before they begin
processing and throw away any block that was from des-ii-1.  Older
clients will process des-ii-1 blocks just as happily as des-ii-2
blocks, however.

Newer (280) pproxies and fullproxies will filter out COMPLETED des-ii-1
blocks, but will not hesistate to hand them out.

So, the situation is this:  If you're running 2.7100, you don't have to
worry at all, the client will throw out old blocks automatically.

If you're running pre-2.7100 clients, make sure that any old
buff-in.des files have been deleted.  In addition, if you're running a
pproxy, make sure its des in buffers are empty as well.

So basically, run 2.7100 (if you have a client), or make sure that old
buff-in.des files are gone before des-ii-2 starts.

Mike "Silby" Silbersack
silby at execpc.com
Distributed.Net Tech Support

We cracked RC5-56.  We cracked DES.  Can you help us with RC5-64?
Put your idle CPU to work:  Add it to the world's LARGEST computer.

To unsubscribe, send 'unsubscribe rc5' to majordomo at lists.distributed.net
rc5-digest subscribers replace rc5 with rc5-digest

More information about the rc5 mailing list