Method and apparatus for using client puzzles to protect against denial-of-service attacks
US6944663B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 6, 2002 |
| Grant date | Sep 13, 2005 |
| Priority date | — |
| Expiry date | Mar 2, 2024 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L63/1458
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
One embodiment of the present invention provides a system that protects a server against denial-of-service attacks. During operation, the server receives a request for service from a client. Note that the client can be distinguished from other clients, for example, by its source IP address. In response to this request, the server sends a random number, y, and an identifier, id1, to the client, and allows the client to compute a preimage, x, such that y=h(x). Upon receiving an answer from the client including the preimage x and an identifier, id2, the server verifies that the identifier, id1, sent to the client matches the identifier, id2, received from the client. If the identifiers match, the server computes h(x), and compares h(x) against y. If h(x)=y, the server performs the requested service for the client. In this way, the server avoids computing h(x) until the server receives the answer with a matching identifier.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.