| 摘要 |
PROBLEM TO BE SOLVED: To intercept an analysis of data on a date and time written into password data or a system, to prevent the invalidation of a check routine during an effective period in software, and to perform the extension or revalidation of the effective period without performing content change or reinstallation of a software package. SOLUTION: Password data PWa not including information on the effective period delivered at a certain instant functions, as a password valid for a certain period, in target software. The whole or an important part of the software is encoded using a certain password PWb beforehand, and PWb can be derived, by a simple mathematical expression, from the password data PWa in the effective period and the present time. In addition, from password data PWa1 at a certain instant, a password PWa2 valid for the next period cannot be presumed. COPYRIGHT: (C)2005,JPO&NCIPI |
