----- Original Message ----- From: "Brian J. Beesley" <[EMAIL PROTECTED]> To: "Torben Schlüntz" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Sent: Saturday, September 21, 2002 8:51 AM Subject: Re: Mersenne: TF - an easy way to cheat
> On Friday 20 September 2002 22:42, Torben Schlüntz wrote: > > Anyone receiving a TF task could edit the worktodo.ini from > > Factor=20.abc.def,59 > > to > > Factor=20.abc.def,65 > > He would receive approx. twice the credit the effort is worth. > > Not quite - even allowing for the 1/2^6 effort involved in TF through 59 bits > ... through 64 bits the algorithm runs much faster than it does for 65 bits > and above. The factor is around 1.6 rather than 2. Good point, and one which I didn't consider in my reply. But the ratio must be different for the P4, which uses SSE2 code for factorisation over 64 bits. > Suggestion: TF should report completion of each "bit" to PrimeNet, not just > the on completion to the target depth. I don't see how this would require > changes to the server, though there would be a (relatively small) increase in > load. According to undoc.txt:- "You can limit how far the program tries to factor a number. This feature should not be used with the Primenet server.", which implies that something bad will happen if you do. > Suggestion: the TF savefile should be modified to contain an internal > consistency check (say the MD5 checksum of the decimal expansion of the > current factoring position) so that cheating by editing the savefile, causing > "jumping" past a large range of possible factors, would be made a great deal > more difficult. Easily cracked. Why not just encrypt it? > Regards > Brian Beesley Daran G. _________________________________________________________________________ Unsubscribe & list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
