Patent ID: 8116450

Claim:
A computer implemented method for measuring trust in a transaction over a public key certificate network, the method performed by the computer comprising the steps of: providing a public key certificate network comprising a directed acyclic graph whose nodes are public keys and wherein an edge K A →K B implies an owner of public key K A is in possession of a certificate for public key K B ; associating each edge K A →K B of said public key certificate network connecting two public keys K A , owned by A, and K B , owned by B, with a probability p, according to A, that information about K B is reliable, and a confidence c that is a total dollar amount of transactions which have involved using edge K A →K B ; forming one or more authentication paths in said public key certificate network starting from a certificate authority having public key K S and ending with a target public key K T ; calculating a limit l on an amount of insurance that an owner of K S is willing to provide to a user interested in a transaction with an owner of K T ; and for each amount m<l, calculating a premium for which the owner of K S is willing to sell insurance to said user for an amount of m, by calculating a maximum amount insurable, f i , for each authentication path i, and calculating an insurance premium rate s i for each authentication path by calculating, for each public key node in said authentication path, starting at K S , s i from a formula ( s i −a i ) p i −(1−δ i )(1 −p i )=γ, wherein p i is a probability of accuracy for each authentication path i, S i is the selling price of said premium, a i is an amount that S, the owner of K S , pays to A, the owner of K A for insuring δ i , fraction of the amount, and γ is a fraction expected profit per transaction expected by S, and wherein for each subsequent public key node A i in said authentication path, the associated s i , will be the a i , paid from A i 's predecessor node and the a i , will be the amount paid to A i 's successor node.