[RC5] Time to Completion

gindrup at okway.okstate.edu gindrup at okway.okstate.edu
Fri Apr 3 11:19:06 EST 1998


     Well, a month ago it was 50 years.  Four months ago, it was 500 
     years.  Assuming exponential growth in the effort (born out by the 
     data to date), our time to complete halving rate is about 7 weeks.  
     In 7 months it will have halved 4 more times to 2.5 years.  In 14 
     months it will have halved 8 more times to 0.16 years, so a 
     reasonable estimate for the complete exhaustion of the keyspace is a 
     year.
     
     Of course, reality must intrude at some point.  After 4 doublings, 
     it will take more than 24 hours for stats to update.  We'd be doing 
     something like 200Gkps ~= 745 blocks/second ~= 373kBps of proxy 
     transmissions (assuming ~500 bytes per block in and out for 
     amortized handshaking and data payload).  That's rather a load on 
     the proxy network.
     
     Also, is it reasonable to expect continued doublings on this 
     schedule?  I think so since we've pretty much held this rate through 
     RC5-56 and DES-II (although for a brief period after DES-I the 
     RC5-56 doubling rate was closer to 4 weeks).
            -- Eric Gindrup ! gindrup at okway.okstate.edu


______________________________ Reply Separator _________________________________
Subject: [RC5] Time to Completion 
Author:  <rc5 at llamas.net> at SMTP
Date:    3/31/98 10:04 AM


     
Hi --
     
Sorry if this is redundant, stupid, etc. I've been running a client 
for a while but I just joined this list.
     
Doing a naieve calculation based on rc5stats:
     
 ((1 - "keyspace exhausted") / "keyspace completed yesterday" ) / 365
     
yields something like 39 years.
     
I know: this does not take into account anticipated growth 
in participants, client speed, etc. Do we have a better 
estimate for TTC? 
     
Robert
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