[RC5] Time to completion

Bruce Ford b.ford at qut.edu.au
Fri Jun 5 14:50:39 EDT 1998


Data used is RC5 2^28 blocks completed each GMT day as reported on the
rc5stats main page.

Regression basis:

1. Assuming linear growth. 
   Data from 4 Dec 97 to 12 Jan 97 (excluding 10 Dec 97) and 
   2 Mar 98 to 4 Jun 98.

2. Assuming linear growth.
   Data from 2 Mar 98 to 4 Jun 98.

3. Assuming exponential growth.
   Data from 4 Dec 97 to 12 Jan 97 (excluding 10 Dec 97) and 
   2 Mar 98 to 4 Jun 98.

4. Assuming exponential growth.
   Data from 2 Mar 98 to 4 Jun 98.

These give: (with previous regressions from 28 May 98 and 21 May 98)

1. Rate grows at 15300 blocks per day. (14598, 13980)
   Keyspace complete in 7.2 years.     (7.4, 7.6)
   50% chance of finding key before 8 Apr 2003.

2. Rate grows at 25392 blocks per day. (24736, 24395)
   Keyspace complete in 5.7 years.     (5.8, 5.9)
   50% chance of finding key before 18 Apr 2002.

3. Rate doubles every 196 days.    (201, 207)
   Keyspace complete in 2.9 years. (3.0, 3.1)
   50% chance of finding key before 23 Oct 2000.

4. Rate doubles every 133 days.    (133, 133)
   Keyspace complete in 2.1 years. (2.2, 2.2)
   50% chance of finding key before 15 Mar 2000.


Eric's factor of 2.8 matches closely that predicted by 4 above.
For 213 days (7 months) 4 gives a factor of 3.0 [2^(213/133)].

Bruce Ford

Bruce Ford                                      b.ford at qut.edu.au
Systems Programmer
Teaching and Learning Support Services          Ph: +61 7 3864 3383
Queensland University of Technology
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