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1. (WO2009136361) EXPONENT OBFUSCATION
Latest bibliographic data on file with the International Bureau   

Pub. No.:    WO/2009/136361    International Application No.:    PCT/IB2009/051837
Publication Date: 12.11.2009 International Filing Date: 05.05.2009
IPC:
G06F 7/72 (2006.01)
Applicants: IRDETO CORPORATE B.V. [NL/NL]; Taurusavenue 105 NL-2132 LS Hoofddorp (NL) (For All Designated States Except US).
MICHIELS, Wilhelmus, P., A., J. [NL/NL]; (NL) (For US Only).
GORISSEN, Paulus, M., H., M., A. [NL/NL]; (NL) (For US Only)
Inventors: MICHIELS, Wilhelmus, P., A., J.; (NL).
GORISSEN, Paulus, M., H., M., A.; (NL)
Agent: Metman, Karel Johannes; De Vries & Metman Overschiestraat 180 1062 XK Amsterdam (NL)
Priority Data:
08155798.5 07.05.2008 EP
Title (EN) EXPONENT OBFUSCATION
(FR) DISSIMULATION D'EXPOSANT.
Abstract: front page image
(EN)A method of obfuscating an exponentis provided. The method comprises identifying (304) a value λ for which it holds that λ>0 and xλ = 1 for a plurality of elements x which are to be used in a cryptographic process. The method further comprises identifying (306) an obfuscated exponent ywhich is greater than λ and providing (308) information indicative of the obfuscated exponent y.The method comprises establishing a keyvalue a, wherein a < λ, selecting a positive integer b, and computing y = a + bλ.
(FR)L'invention porte sur un procédé de dissimulation d'un exposant. Le procédé consiste à identifier (304) une valeur λ pour laquelle λ > 0 et ϰλ = 1 pour une pluralité d'éléments x qui doivent être utilisés dans un traitement cryptographique; à identifier (306) un exposant dissimulé y qui est supérieur à λ et à délivrer (308) des informations indicatives de l'exposant dissimulé y; à établir une valeur clé a pour laquelle a < λ, à sélectionner un entier positif b et à calculer y = a + bλ.
Designated States: AE, AG, AL, AM, AO, AT, AU, AZ, BA, BB, BG, BH, BR, BW, BY, BZ, CA, CH, CN, CO, CR, CU, CZ, DE, DK, DM, DO, DZ, EC, EE, EG, ES, FI, GB, GD, GE, GH, GM, GT, HN, HR, HU, ID, IL, IN, IS, JP, KE, KG, KM, KN, KP, KR, KZ, LA, LC, LK, LR, LS, LT, LU, LY, MA, MD, ME, MG, MK, MN, MW, MX, MY, MZ, NA, NG, NI, NO, NZ, OM, PG, PH, PL, PT, RO, RS, RU, SC, SD, SE, SG, SK, SL, SM, ST, SV, SY, TJ, TM, TN, TR, TT, TZ, UA, UG, US, UZ, VC, VN, ZA, ZM, ZW.
African Regional Intellectual Property Organization (BW, GH, GM, KE, LS, MW, MZ, NA, SD, SL, SZ, TZ, UG, ZM, ZW)
Eurasian Patent Organization (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM)
European Patent Office (AT, BE, BG, CH, CY, CZ, DE, DK, EE, ES, FI, FR, GB, GR, HR, HU, IE, IS, IT, LT, LU, LV, MC, MK, MT, NL, NO, PL, PT, RO, SE, SI, SK, TR)
African Intellectual Property Organization (BF, BJ, CF, CG, CI, CM, GA, GN, GQ, GW, ML, MR, NE, SN, TD, TG).
Publication Language: English (EN)
Filing Language: English (EN)