Modular inversion that is protected against espionage
US7474748B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | May 13, 2003 |
| Grant date | Jan 6, 2009 |
| Priority date | — |
| Expiry date | Apr 8, 2025 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F2207/7247
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
In methods for determining, in a way that is protected against spying, the modular inverse b of a value a in relation to a module n for a cryptographic application, an auxiliary value β and an auxiliary module δ are determined at least depending on the value a, the module n and at least one masking parameter r, an auxiliary inverse β′ is determined as the modular inverse of the auxiliary value β in relation to the auxiliary module δ, and the modular inverse b is determined at least depending on the auxiliary inverse β′, the at least one masking parameter r, and the auxiliary value β and/or the auxiliary module δ. A computer program product and a portable data carrier have corresponding features. The invention provides a method for modular inversion, secured against spying, which is suitable for applications where security is critical, such as, e.g. cryptographic calculations on a portable data carrier.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.