Re: Email Web of Trust

Alan DeKok wrote:

> Yakov Shafranovich <[email protected]> wrote:
> 
>>>[ simple "link" web of trust has issues ]
>>
>>Then the real question becomes, what class of spam and what 
>>aspects/types of spam problems does this "web of trust" idea solve?
> 
> 
>   It gives recipients more information.  It allows recipients to "ask
> around" about a "new guy", and get a recommendation "good/bad/ugly".
> 
>   This web of trust is no different than that used in job interviews.
> Sure, someone's resume may look wonderful, and they may come across as
> competent, but if the web of trust says "after 3 months, he shows up
> at work drunk", you probably don't want to hire him.
> 
>   The sole purpose of the web of trust is to make better decisions
> earlier in time.  You could accept gigabytes of crap from an MTA you
> haven't heard of before, or you could be told "that MTA will send you
> gigabytes of crap".  You would probably then decide to not talk to it.
> 
>   It doesn't stop the spam problem.  It reduces the local cost of
> dealing with the spam problem.  Look at it as leveraging the CPU time
> and $$ of everyone else, to make your decisions.
> 

It sounds more and more to me like a "web of reputation" rather than a 
"web of trust" to me. The catch of course would be defining the 
information that is being passed around.

What I am looking for is a one or two sentence problem statement for 
this concept, similar to what we have in the LMAP document:

"  LMAP attacks the forgery problem by checking that the host
    from which the message was sent is authorized to send mail
    using the a domain in the message's envelope.
"

What I am looking for is something similar for this. Another important 
point is what John mentioned - ISP MTAs which are sending out spam along 
with legit email. For these, unless the percentage of spam becomes 
really big, the web of trust will not help with. Therefore, IMHO such 
"web of trust" is more geared towards reducing the problem with hijacked 
computers, or IPs/domains that have are not supposed to be MTAs. If this 
in fact is true, than a web of trust method might not be better than 
other methods to address the problem.

If on the other hand, this is simply a way to allow multiple systems to 
collaborate on a combined reputation system, that might be different. 
Systems like DCC address a different issue - detecting spam or spammers 
over a distributed network. For example, with DomainKeys an identical 
spam message can be sent out in a replay attack which will not 
necessarily be caught by one system. In a DCC-like environment, multiple 
systems can collaborate and catch such occurance.

> 
>   Also, because the web of trust can be designed to have confidence
> values on the links, it doesn't have the problem that you have to
> either trust someone elses input absolutely, or you don't trust it at
> all.  Systems with binary trust values just don't work in the long run.
> 

Agreed, the whole notion of binary trust values is one of the problems 
with blacklists today.

Yakov