Cryptography using multi-factor key system and finite state machine

A computer program product comprising:

• a computer readable storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method comprising:
• obtaining a specification of a finite-state machine that accepts a language over an input alphabet;
• receiving, by a message recipient that comprises a first computing device, an encrypted language element of the language;
• decrypting the encrypted language element using one or more private keys of a plurality of private keys the decrypting providing a respective one or more decrypted language elements;
• identifying, using the finite-state machine, a decrypted language element, of the one or more decrypted language elements, that is accepted by the finite-state machine;
• identifying a private key, of the plurality of private keys, used in the decrypting that provided the decrypted language element identified as being accepted by the finite-state machine;
• receiving, by the message recipient, from a message sender that comprises a second computing device, an encrypted message over a communication network;
• and
• using the identified private key in decrypting the encrypted message.

A computer system comprising:

• a memory device;
• and
• a hardware processor in communication with the memory, wherein the computer system is configured to perform a method comprising:
• obtaining a specification of a finite-state machine that accepts a language over an input alphabet;
• receiving, by a message recipient that comprises a first computing device, an encrypted language element of the language;
• decrypting the encrypted language element using one or more private keys of a plurality of private keys the decrypting providing a respective one or more decrypted language elements;
• identifying, using the finite-state machine, a decrypted language element, of the one or more decrypted language elements, that is accepted by the finite-state machine;
• identifying a private key, of the plurality of private keys, used in the decrypting that provided the decrypted language element identified as being accepted by the finite-state machine;
• receiving, by the message recipient, from a message sender that comprises a second computing device, an encrypted message over a communication network;
• and
• using the identified private key in decrypting the encrypted message.