[hashcash] Re: Problem with PowerPC Altivec engine
- From: Jonathan Morton <chromi@xxxxxxxxxxxxxxxxxxxxx>
- To: hashcash@xxxxxxxxxxxxx
- Date: Mon, 31 Jan 2005 22:22:04 +0000
It fails about one time in 5 or so.
I'm guessing that it fails more often when higher bit counts are used
- the bug appears to be in the "wraparound" code used when more than
2^31 iterations are needed to find a collision. The problem is that
when wrapping, the "tail" position is not reset, but it is updated in
the body of the loop.
This indeed seems to be the case - I fixed that bug, and got 10 good
stamps in a row immediately afterwards.
Arowana:~/download/hashcash-1.16 chromi$ ./hashcash -m -b 29 -r
71672bc400000017-000003c2-0001.rpow.net
hashcash token:
1:29:050131:71672bc400000017-000003c2-0001.rpow.net::PFQGGOfPKOqjhbaH:
000000000000000000000Bz0iQ
Arowana:~/download/hashcash-1.16 chromi$ ./hashcash -m -b 29 -r
71672bc400000017-000003c2-0001.rpow.net
hashcash token:
1:29:050131:71672bc400000017-000003c2-0001.rpow.net::dMztK30vhsezAoYa:
0000000000000000000007nR7k
Arowana:~/download/hashcash-1.16 chromi$ ./hashcash -m -b 29 -r
71672bc400000017-000003c2-0001.rpow.net
hashcash token:
1:29:050131:71672bc400000017-000003c2-0001.rpow.net::XhZt2zcDoqAtL6yR:
0000000000000000000006N7nk
Arowana:~/download/hashcash-1.16 chromi$ ./hashcash -m -b 29 -r
71672bc400000017-000003c2-0001.rpow.net
hashcash token:
1:29:050131:71672bc400000017-000003c2-0001.rpow.net::sL8B5qLFKoj8duDF:
000000000000000000000kpbPL
Arowana:~/download/hashcash-1.16 chromi$ ./hashcash -m -b 29 -r
71672bc400000017-000003c2-0001.rpow.net
hashcash token:
1:29:050131:71672bc400000017-000003c2-0001.rpow.net::0CWPrpTceaFJFxCY:
000000000000000000000Jx1Cd
Arowana:~/download/hashcash-1.16 chromi$ ./hashcash -m -b 29 -r
71672bc400000017-000003c2-0001.rpow.net
hashcash token:
1:29:050131:71672bc400000017-000003c2-0001.rpow.net::343tGahxKEBnbjgw:
000000000000000000000dfzkm
Arowana:~/download/hashcash-1.16 chromi$ ./hashcash -m -b 29 -r
71672bc400000017-000003c2-0001.rpow.net
hashcash token:
1:29:050131:71672bc400000017-000003c2-0001.rpow.net::ZIw+oWdHFLQ3Spno:
000000000000000000000WjvrU
Arowana:~/download/hashcash-1.16 chromi$ ./hashcash -m -b 29 -r
71672bc400000017-000003c2-0001.rpow.net
hashcash token:
1:29:050131:71672bc400000017-000003c2-0001.rpow.net::OU3oKHlEPdxt2eoa:
0000000000000000000004EtCU
Arowana:~/download/hashcash-1.16 chromi$ ./hashcash -m -b 29 -r
71672bc400000017-000003c2-0001.rpow.net
hashcash token:
1:29:050131:71672bc400000017-000003c2-0001.rpow.net::watWd9k1NxsOgbNv:
0000000000000000000003y+1m
Arowana:~/download/hashcash-1.16 chromi$ ./hashcash -m -b 29 -r
71672bc400000017-000003c2-0001.rpow.net
hashcash token:
1:29:050131:71672bc400000017-000003c2-0001.rpow.net::tvr0Rh0pt4lrfPYi:
000000000000000000000Sg2NP
--------------------------------------------------------------
from: Jonathan "Chromatix" Morton
mail: chromi@xxxxxxxxxxxxxxxxxxxxx
website: http://www.chromatix.uklinux.net/
tagline: The key to knowledge is not to rely on people to teach you it.
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