Method for self-synchronizing time between communicating networked systems using timestamps
US7676679B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 15, 2005 |
| Grant date | Mar 9, 2010 |
| Priority date | — |
| Expiry date | Jul 16, 2028 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L63/1466
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
Nodes in a network include a pseudo-timestamp in messages or packets, derived from local pseudo-time clocks. When a packet is received, a first time is determined representing when the packet was sent and a second time is determined representing when the packet was received. If the difference between the second time and the first time is greater than a predetermined amount, the packet is considered to be stale and is rejected, thereby deterring replay. Because each node maintains its own clock and time, to keep the clocks relatively synchronized, if a time associated with a timestamp of a received packet is later than a certain amount with respect to the time at the receiver, the receiver's clock is set ahead by an amount that expected to synchronize the receiver's and the sender's clocks. However, a receiver never sets its clock back, to deter attacks.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.