Efficient exponentiation method and apparatus
US6745220B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Nov 21, 2000 |
| Grant date | Jun 1, 2004 |
| Priority date | — |
| Expiry date | Aug 27, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F2207/7295
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
An encryption/decryption method performs an exponentiation operation on a base number where both the base number and the exponent may be large numbers (i.e., anywhere from 100 to several thousand bits long). The exponent is expressed as a bit string. The bit string is then re-coded utilizing the signed digit algorithm. Predetermined substring patterns are then extracted from the exponent utilizing a string replacement method and compared to a previously constructed look-up table containing exponent values for only a relatively small number of predetermined substrings. The value returned from the look-up table is the base value raised to the power represented by the substring. A pointer for each matching substring in the exponent is stored. The remaining bits in the exponent and intermediate values and are then processed with the base value using a multiply chain algorithm to determine the value of the base raised to the exponent.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.