Implementation of Bram's trust metric
I've implemented Bram's probablistic trust metric: see this Advogato diary entry:
http://www.advogato.org/person/ciphergoth/diary.html?start=5
Update: - just got mail from Bram indicating that this isn't the metric he wanted to propose. More to follow.
The metric is very simple - it measures the probability that a person is reachable from the "trust source" if half the nodes at random are removed. It does this simply by marking every node invalid with probability 0.5, finding out which nodes are reachable, incrementing a counter on them all, then re-sampling 1000 times.
It seems to give plausible results, and on the Advogato graph (4000 active nodes, 40000 arcs) it takes 6 seconds to do 1000 iterations (which gives results to a precision of about 1.6%, where 100% is maximum trust). It's a combination of Perl and C.
brams-metric-0.1.tar.gz
To test it, you'll need the Advogato trust graph. Thanks to Gary Benson for pointing out that this is available as a graphviz .dot file here:
http://www.advogato.org/person/graph.dot
This is the form that my current implementation expects the trust graph to be in. There's a simple test command line in the Makefile.
This trust metric offers a limited form of attack resistance, but no resistance against crapflooding.
http://www.advogato.org/person/ciphergoth/diary.html?start=5
Update: - just got mail from Bram indicating that this isn't the metric he wanted to propose. More to follow.
The metric is very simple - it measures the probability that a person is reachable from the "trust source" if half the nodes at random are removed. It does this simply by marking every node invalid with probability 0.5, finding out which nodes are reachable, incrementing a counter on them all, then re-sampling 1000 times.
It seems to give plausible results, and on the Advogato graph (4000 active nodes, 40000 arcs) it takes 6 seconds to do 1000 iterations (which gives results to a precision of about 1.6%, where 100% is maximum trust). It's a combination of Perl and C.
brams-metric-0.1.tar.gz
To test it, you'll need the Advogato trust graph. Thanks to Gary Benson for pointing out that this is available as a graphviz .dot file here:
http://www.advogato.org/person/graph.dot
This is the form that my current implementation expects the trust graph to be in. There's a simple test command line in the Makefile.
This trust metric offers a limited form of attack resistance, but no resistance against crapflooding.