Patent ID: 7228418

Claim:
An authentication method that implements a first entity known as “to be authenticated” (A) and a second entity known as “authenticating” (B) to a desired security level, said method comprising the steps of: determining P by taking the entity to be authenticated (A) as having a computation capacity of 2 P in a determined time (Δt max ), with said P ranging between 0 and 80, determining an integer k such that the desired security level is equal to 1−2 −k , the entity to be authenticated (A) sending at least one pre-commitment or commitment c to the authenticating entity (B), said pre-commitment or commitment being made at least (k+P) bits long, the authenticating entity (B) receiving said pre-commitment or commitment c, and thereupon selecting a number e called “question” at random and then sending said question e to the entity to be authenticated (A). the entity to be authenticated (A) receiving said question e, and performing computing operations using said question e, the result of said computing operations constituting a response y, and then sending said response y to the authenticating entity (B), the authenticating entity (B) receiving said response y, and then performing a computing operation using said response y and checking that the computing operation results in the pre-commitment or commitment c having been received, authenticating entity (B) measuring the time Δt between the moment when the entity to be authenticated (A) is being addressed by entity (B) and the moment when entity (B) receives the response from the entity to be authenticated (A), and authenticating entity (B) checking that the measured time Δt is shorter than the determined time Δt max , thereby resulting in entity (B) authenticating the identity of entity (A).