US 11,991,266 B2
Fully homomorphic cryptography with improved data item representation
Marc Joye, Saint Zacharie (FR)
Assigned to ZAMA SAS, Paris (FR)
Appl. No. 18/250,809
Filed by ZAMA SAS, Paris (FR)
PCT Filed Oct. 28, 2021, PCT No. PCT/EP2021/080017
§ 371(c)(1), (2) Date Apr. 27, 2023,
PCT Pub. No. WO2022/090407, PCT Pub. Date May 5, 2022.
Claims priority of application No. 20290073 (EP), filed on Oct. 29, 2020.
Prior Publication US 2023/0396409 A1, Dec. 7, 2023
Int. Cl. H04L 9/00 (2022.01); G06N 3/048 (2023.01)
CPC H04L 9/008 (2013.01) [G06N 3/048 (2023.01)] 23 Claims
OG exemplary drawing
 
1. A method for performing a computation using fully homomorphic encryption (FHE) cryptography, the computation comprising a set of FHE operations implementing the computation and operating on encrypted data items, an encrypted data item having an associated noise level, the method comprising:
(a) receiving one or more encrypted data items for the computation from a data-provider system, the one or more encrypted data items being encrypted with an encryption key of the data-provider system,
(b) performing the set of FHE operations on encrypted data items including the received encrypted data items,
(c) clipping an encrypted data item, thereby reducing a bit-size of one or more numbers representing the encrypted data item and increasing an associated noise level of the encrypted data item, wherein an FHE operation or a decrypt operation operates on the clipped encrypted data item as input, a noise level associated with the input being below a noise tolerance of the FHE operation or decrypt operation, and
(d) storing the clipped encrypted data item for later FHE processing, and/or transmitting the clipped encrypted data item for further FHE processing on a further device.