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1. IN201827017448 - KEY SEQUENCE GENERATION FOR CRYPTOGRAPHIC OPERATIONS

Office India
Application Number 201827017448
Application Date 09.05.2018
Publication Number 201827017448
Publication Date 13.07.2018
Publication Kind A
IPC
H04L 9/06
HELECTRICITY
04ELECTRIC COMMUNICATION TECHNIQUE
LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
9Arrangements for secret or secure communication
06the encryption apparatus using shift registers or memories for blockwise coding, e.g. D.E.S. systems
Applicants NAGRAVISION SA
Inventors VILLEGAS Karine
WYSEUR Brecht
Priority Data 1519612.4 06.11.2015 UK
Title
(EN) KEY SEQUENCE GENERATION FOR CRYPTOGRAPHIC OPERATIONS
Abstract
(EN)
Methods system and devices are provided that generate a sequence of sub keys for cryptographic operations from a main key. The main key is operated on only once to generate the sub keys of the sequence with a transformation comprising one or more one way functions. The respective bit values of the sub keys of the sequence are set using respective bit values of the one or more one way functions. Advantageously deriving sub key bits from respective output bits of one or more one way functions removes or at least reduces correlations between the main key and the sub keys as well as between sub keys making it harder or even impossible to recover the main key or other sub keys from a single sub key for example as found using a side channel attack. At the same time by using the main key only once (rather than using the main key each time a sub key is generated) the vulnerability of the main key to a side channel attack is reduced because the opportunities for recovering physical information that could lead to the discovery of the main key are reduced. Specific embodiments use parallel or chained execution of sub functions to generate respective sub keys. Other specific embodiments generate all sub keys from a single one way function in one go.