Patent ID: 8688973

Claim:
A computer-implemented method of securing communications sent by a first user to a second user, the method comprising: receiving, by a first user from a trusted third party, at least one public cryptographic value corresponding to the first user and at least one private cryptographic value corresponding to the first user, wherein the at least one public cryptographic value of the first user and the at least one private cryptographic value of the first user include at least one value generated by the trusted third party; storing, by the first user, a plurality of values on an identification device identified by an identifier, the plurality of values including a first value that is a function of a cryptographic identifier of the identification device and a second value that is a function of the at least one private cryptographic value of the first user; deriving, by the first user, a shared key using the at least one private cryptographic value of the first user, and at least one of the plurality of values stored on the identification device identified by the identifier; receiving, by the second user, the identification device; deriving, by the second user, the shared key using a private cryptographic value of the second user and at least one of the plurality of values stored on the identification device; and protecting communications sent by the first user to the second user with the shared key.