System and method of verifying cryptographic postage evidencing using a fixed key set
US5982896A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 23, 1996 |
| Grant date | Nov 9, 1999 |
| Priority date | — |
| Expiry date | Dec 23, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG07B2017/00919
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A method for controlling keys used in the verification of encoded information generated by a transaction evidencing device and printed on a document comprises the steps of generating a plurality of random verifier master keys to obtain a set of verifier master keys consisting of a fixed number of keys; generating at least one pointer by applying a psuedorandom algorithm to data unique to the transaction evidencing device; calculating a plurality of verifier token keys to obtain a verifier token key set corresponding to the set of verifier master keys; encrypting the verifier token key set with a privacy key; and distributing the set verifier token keys and the privacy key to verifiers. The token keys are a function of the verifier master keys and a code valid for a limited time. The pointer algorithm is an appropriate symmetric key cryptographic algorithm and the code is function of a date dependent parameter. The master keys are distributed to postal and vendor data centers.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.