Cryptography using multi-factor key system and finite state machine

Abstract

A process receives a specification of a finite-state machine and an encrypted language element of a language over an input alphabet for the finite-state machine. The received encrypted language element is encrypted with a selected public key of a plurality of public keys. The process decrypts the encrypted language element using each private key of a plurality of private keys corresponding to the public keys. The decrypting provides a plurality of decrypted language elements and the process applies each decrypted language element to the finite-state machine. The process identifies a decrypted language element that that is accepted by the finite-state machine. The process identifies a private key, of the private keys, used in the decrypting that provided the decrypted language element identified as being accepted by the finite-state machine. The process receives from the message sender an encrypted message, and uses the identified private key in decrypting the encrypted message.