[cryptography] PKI - and the threat model is ...?

dan at geer.org dan at geer.org
Tue Sep 13 07:36:16 EDT 2011


 | 
 | let's take just one of the above as an example: high-value monetary
 | transactions - the only item in the list that I am somewhat familiar
 | with.
 | 
 | I can not think of a single scenario where the two parties that do
 | that, prefer a trust chain that includes a third party for introduction
 | and identity vouching instead of the out-of-channel shared secret
 | or key fingerprint exchange. However, secure mass retail system is
 | pretty well impossible without such trusted third party.
 | 



Premise:

The higher the value of the transaction, the less likely it is done
between parties that do not already know each other.

Consequent:

The market opportunity is in protecting 1,000,000 x $10 transactions,
not protecting 10 x $1,000,000 transactions.

Complicating Factor:

The fully automated opponent sees those two multiplications as equal.



--dan




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