Cryptography using multi-factor key system and finite state machine

• US 10,609,003 B2
• Filed: 04/03/2019
• Issued: 03/31/2020
• Est. Priority Date: 04/25/2017
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Jawaharlal, Samuel M., Narayanan, Arunachalam, Santhar, Sathya, Sivaramalingam, Balamurugaramanathan
• Primary Examiner(s): Gracia, Gary S
• Application Number:
  US16/374,260
• Publication Number:
  US 20190238521A1
• Time in Patent Office: 363 Days
• Field of Search: 380 46, 380 47, 713189
• CPC Class Codes: H04L 63/0442 wherein the sending and receiving network entities apply asymmetric encryption, i.e. different keys for encryption and decryption cryptographic mechanisms or cryptographic arrangements for public-key encryption H04L9/30
• CPC Class Codes: H04L 9/14 using a plurality of keys or algorithms
• CPC Class Codes: H04L 9/30 Public key, i.e. encryption algorithm being computationally infeasible to invert or user's encryption keys not requiring secrecy
• CPC Class Codes: H04L 9/3006 underlying computational problems or public-key parameters

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.

Claims

1. A computer-implemented method comprising:

receiving, by a message recipient that is to receive an encrypted message over a communication network from a message sender, (i) a specification of a finite-state machine and (ii) an encrypted language element of a language over an input alphabet for the finite-state machine, wherein the finite-state machine accepts the language, wherein the language comprises language elements, and wherein the received encrypted language element is encrypted with a selected public key of a plurality of public keys;

decrypting the encrypted language element using each private key of a plurality of private keys, the plurality of private keys corresponding to the plurality of public keys, and the decrypting providing a plurality of decrypted language elements;

applying each decrypted language element to the finite-state machine;

identifying, based on the applying, a decrypted language element, of the plurality of decrypted language elements, that 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 from the message sender the encrypted message over the communication network; and

using the identified private key in decrypting the encrypted message.

2. The method of claim 1, wherein the language is a regular language and the finite-state machine accepts only the elements of the language.

3. The method of claim 1, further comprising providing an indication to the message sender that electronic transmission of the encrypted message is to commence.

4. The method of claim 3, wherein the providing the indication is performed based on the identifying the private key.

5. The method of claim 1, further comprising generating the plurality of private keys and the plurality of public keys corresponding thereto as cryptographic key pairs.

6. The method of claim 5, further comprising providing the plurality of public keys to the message sender.

7. The method of claim 1, wherein the encrypted message is one message of a plurality of encrypted messages of a session between the message recipient and the message sender, and wherein the method further comprises repeating, one or more times during the session, the receiving an encrypted language element, the decrypting the encrypted language element using each private key, the applying each decrypted language element to the finite-state machine, the identifying a decrypted language element, and the identifying a private key used in the decrypting, wherein the repeating facilitates an intra-session coordinated change between the message sender and the message recipient in a key pair used in encrypted message passing as part of the session.

8. 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;

receiving, by a message recipient that is to receive an encrypted message over a communication network from a message sender, (i) a specification of a finite-state machine and (ii) an encrypted language element of a language over an input alphabet for the finite-state machine, wherein the finite-state machine accepts the language, wherein the language comprises language elements, and wherein the received encrypted language element is encrypted with a selected public key of a plurality of public keys;

decrypting the encrypted language element using each private key of a plurality of private keys, the plurality of private keys corresponding to the plurality of public keys, and the decrypting providing a plurality of decrypted language elements;

applying each decrypted language element to the finite-state machine;

identifying, based on the applying, a decrypted language element, of the plurality of decrypted language elements, that 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 from the message sender the encrypted message over the communication network; and

using the identified private key in decrypting the encrypted message.

9. The computer program product of claim 8, wherein the language is a regular language and the finite-state machine accepts only the elements of the language.

10. The computer program product of claim 8, wherein the method further comprises providing an indication to the message sender that electronic transmission of the encrypted message is to commence.

11. The computer program product of claim 10, wherein the providing the indication is performed based on the identifying the private key.

12. The computer program product of claim 8, wherein the method further comprises generating the plurality of private keys and the plurality of public keys corresponding thereto as cryptographic key pairs.

13. The computer program product of claim 12, wherein the method further comprises providing the plurality of public keys to the message sender.

14. The computer program product of claim 8, wherein the encrypted message is one message of a plurality of encrypted messages of a session between the message recipient and the message sender, and wherein the method further comprises repeating, one or more times during the session, the receiving an encrypted language element, the decrypting the encrypted language element using each private key, the applying each decrypted language element to the finite-state machine, the identifying a decrypted language element, and the identifying a private key used in the decrypting, wherein the repeating facilitates an intra-session coordinated change between the message sender and the message recipient in a key pair used in encrypted message passing as part of the session.

15. A computer system comprising:

a memory; and

a processor in communications with the memory, wherein the computer system is configured to perform a method comprising;

receiving, by a message recipient that is to receive an encrypted message over a communication network from a message sender, (i) a specification of a finite-state machine and (ii) an encrypted language element of a language over an input alphabet for the finite-state machine, wherein the finite-state machine accepts the language, wherein the language comprises language elements, and wherein the received encrypted language element is encrypted with a selected public key of a plurality of public keys;

decrypting the encrypted language element using each private key of a plurality of private keys, the plurality of private keys corresponding to the plurality of public keys, and the decrypting providing a plurality of decrypted language elements;

applying each decrypted language element to the finite-state machine;

identifying, based on the applying, a decrypted language element, of the plurality of decrypted language elements, that 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 from the message sender the encrypted message over the communication network; and

using the identified private key in decrypting the encrypted message.

16. The computer system of claim 15, wherein the language is a regular language and the finite-state machine accepts only the elements of the language.

17. The computer system of claim 15, wherein the method further comprises providing an indication to the message sender that electronic transmission of the encrypted message is to commence.

18. The computer system of claim 17, wherein the providing the indication is performed based on the identifying the private key.

19. The computer system of claim 15, wherein the method further comprises generating the plurality of private keys and the plurality of public keys corresponding thereto as cryptographic key pairs, and wherein the method further comprises providing the plurality of public keys to the message sender.

20. The computer system of claim 15, wherein the encrypted message is one message of a plurality of encrypted messages of a session between the message recipient and the message sender, and wherein the method further comprises repeating, one or more times during the session, the receiving an encrypted language element, the decrypting the encrypted language element using each private key, the applying each decrypted language element to the finite-state machine, the identifying a decrypted language element, and the identifying a private key used in the decrypting, wherein the repeating facilitates an intra-session coordinated change between the message sender and the message recipient in a key pair used in encrypted message passing as part of the session.