Cryptographic puzzle cancellation service for deterring bulk electronic mail messages
US7660993B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 22, 2004 |
| Grant date | Feb 9, 2010 |
| Priority date | — |
| Expiry date | Feb 26, 2026 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L67/1065
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
Methods and systems are provided for a cancellation server maintaining a database of identifiers of cryptographic puzzles. A cryptographic puzzle is created from a unique identifier and a timestamp, and is attached to an electronic mail message, along with the puzzle's solution. The recipient verifies that the solution is correct and that the timestamp is current, and further queries the cancellation server with the puzzle identifier. If the identifier does not exist in the database, then the recipient knows the received message is legitimate. If the identifier already appears in the database, the received message can be automatically removed from the recipient's computer.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.