[RC5] Random block dupe probability (was Win95 GUI Lurk?)

Jason Bechtel jbechtel at eng.utoledo.edu
Sun May 3 02:33:27 EDT 1998


Dan Petrak wrote:
> 
> [begin quote]
> generating a random block during that time. When you've calculated all this, add a bunch anyway because random blocks have a high probability of being duplicated work. If you want, you could increase the blocksize
> [end quote]
> 
> Given the small percentage of keyspace exhausted so far, I don't think
> random blocks are going to have a "high probability" of duping.

	But since this keyspace is like 256 RC5-56 keyspaces, and there is a
strict hardware limit on how large the current working space can be, we
are limited to doing up to 4 56-bit subspaces at once.  I think I recall
that four are currently open and the master keyserver is reassigning
blocks from some of those subspaces until they are complete.  This way,
when a subspace is complete, the keyserver just says subspace XX is
complete and doesn't have to remember which blocks are done and which
are not.  Then it can begin handing out blocks in another subspace.  So,
as we near the end of a 56-bit subspace, the probability of a randomly
generated block being a duplicate is higher.

Jason Bechtel

PS:  Someone please correct me if I'm wrong, but I'm working on the
assumption that the subspace for random block generation is currently
set to be somewhere within the four open 56-bit subspaces.
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