# US 11,310,039 B2 · Lightweight distributed signature protocol for mobile computing and IoT devices

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- Number: US 11,310,039 B2
- Document ID: US11310039B2
- Status: Granted
- Kind: B2
- Application number: 16/688,311
- Filed: 2019-11-19
- Published: 2020-05-21
- Granted: 2022-04-19
- Earliest claimed: 2018-11-20
- Assignees: Board of Regents, The University of Texas System
- Applicants: Board of Regents, The University of Texas System
- Inventors: Kim Kwang Choo; Debiao He
- Web page: https://patentgrep.com/patent/US11310039B2

## CPC

- H04L 9/083: {involving central third party, e.g. key distribution center [KDC] or trusted third party [TTP]}
- H04L 9/085: {Secret sharing or secret splitting, e.g. threshold schemes}
- H04L 9/0825: {using asymmetric-key encryption or public key infrastructure [PKI], e.g. key signature or public key certificates}
- H04L 9/0866: {involving user or device identifiers, e.g. serial number, physical or biometrical information, DNA, hand-signature or measurable physical characteristics}
- H04L 9/0894: {Escrow, recovery or storing of secret information, e.g. secret key escrow or cryptographic key storage}
- H04L 9/3073: {involving pairings, e.g. identity based encryption [IBE], bilinear mappings or bilinear pairings, e.g. Weil or Tate pairing}
- H04L 9/3247: {involving digital signatures}
- H04L 9/3255: {using group based signatures, e.g. ring or threshold signatures}
- H04L 9/3257: {using blind signatures}
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

The techniques described herein may provide an efficient and secure two-party distributed signing protocol, for example, for the IEEE P1363 standard. For example, in an embodiment, method may comprise generating, at a key generation center, a first partial private cryptographic key for a user ID and a second partial private cryptographic key for the user ID, transmitting the first partial private cryptographic key to a first other device, transmitting the second partial private cryptographic key to a second other device, and generating a distributed cryptographic signature for a message using the first partial private cryptographic key and the second partial private cryptographic key.

## Claims

### Claim 1

A method comprising:
generating, at a key generation center, a first partial private cryptographic key for a user ID and a second partial private cryptographic key for the user ID;
transmitting the first partial private cryptographic key to a first other device;
transmitting the second partial private cryptographic key to a second other device; and
generating a distributed cryptographic signature for a message using the first partial private cryptographic key and the second partial private cryptographic key;
wherein, when the first partial private cryptographic key and the second partial private cryptographic key are combined, a valid private cryptographic key is formed; and
wherein generating the distributed cryptographic signature for the message comprises:
transmitting a request for a cryptographic signature from the first other device to the second other device;
generating at the second other device, in response to receiving the request from the first other device, a first plurality of intermediate values using a plurality of random numbers and the first partial private cryptographic key;
generating at the first other device, in response to receiving the first plurality of intermediate values from the second other device, a second plurality of intermediate values using a plurality of random numbers and the message;
generating, at the second other device, in response to receiving the second plurality of intermediate values from the first other device, a third plurality of intermediate values using the second partial private cryptographic key; and
generating, at the first other device, in response to receiving the third plurality of intermediate values from the second other device, the distributed cryptographic signature using the first partial private cryptographic key.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
generating, at the key generation center, a partial private cryptographic key.

### Claim 3

A system comprising a processor, memory accessible by the processor, and computer program instructions stored in the memory and executable by the processor to perform:
generating, at a key generation center, a first partial private cryptographic key for a user ID and a second partial private cryptographic key for the user ID;
transmitting the first partial private cryptographic key to a first other device;
transmitting the second partial private cryptographic key to a second other device; and
generating a distributed cryptographic signature for a message using the first partial private cryptographic key and the second partial private cryptographic key
wherein, when the first partial private cryptographic key and the second partial private cryptographic key are combined, a valid private cryptographic key is formed; and
wherein generating the distributed cryptographic signature for the message comprises:
transmitting a request for a cryptographic signature from the first other device to the second other device;
generating at the second other device, in response to receiving the request from the first other device, a first plurality of intermediate values using a plurality of random numbers and the first partial private cryptographic key;
generating at the first other device, in response to receiving the first plurality of intermediate values from the second other device, a second plurality of intermediate values using a plurality of random numbers and the message;
generating, at the second other device, in response to receiving the second plurality of intermediate values from the first other device, a third plurality of intermediate values using the second partial private cryptographic key; and
generating, at the first other device, in response to receiving the third plurality of intermediate values from the second other device, the distributed cryptographic signature using the first partial private cryptographic key.

### Claim 4 (depends on 3)

The system of claim 3, further comprising:
generating, at the key generation center, a partial private cryptographic key.

### Claim 5

A computer program product for cryptography, the computer program product comprising a non-transitory computer readable storage having program instructions embodied therewith, the program instructions executable by a computer, to cause the computer to perform a method comprising:
generating, at a key generation center, a first partial private cryptographic key for a user ID and a second partial private cryptographic key for the user ID;
transmitting the first partial private cryptographic key to a first other device;
transmitting the second partial private cryptographic key to a second other device; and
generating a distributed cryptographic signature for a message using the first partial private cryptographic key and the second partial private cryptographic key
wherein, when the first partial private cryptographic key and the second partial private cryptographic key are combined, a valid private cryptographic key is formed; and
wherein generating the distributed cryptographic signature for the message comprises:
transmitting a request for a cryptographic signature from the first other device to the second other device;
generating at the second other device, in response to receiving the request from the first other device, a first plurality of intermediate values using a plurality of random numbers and the first partial private cryptographic key;
generating at the first other device, in response to receiving the first plurality of intermediate values from the second other device, a second plurality of intermediate values using a plurality of random numbers and the message;
generating, at the second other device, in response to receiving the second plurality of intermediate values from the first other device, a third plurality of intermediate values using the second partial private cryptographic key; and
generating, at the first other device, in response to receiving the third plurality of intermediate values from the second other device, the distributed cryptographic signature using the first partial private cryptographic key.

### Claim 6 (depends on 5)

The computer program product of claim 5, further comprising:
generating, at the key generation center, a partial private cryptographic key.