Method and apparatus to maintain encryption synchronization in a multi-modulation TDM system
US7095856B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 29, 2002 |
| Grant date | Aug 22, 2006 |
| Priority date | — |
| Expiry date | Oct 6, 2024 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2209/80
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
Encryption synchronization (e-sync) is maintained between a transmitter (104) and one or more receivers (102) in a multi-modulation TDM system (100) where information is communicated in slots (402) comprising a slot header (404) and one or more data blocks (406), and wherein the data blocks are eligible to be encoded at different modulation rates thereby creating a likelihood of different numbers of blocks in different slots. The receiver and transmitter employ respective encryption elements (200, 300) comprising e-sync shifter elements (202, 302) and encryption algorithm blocks (204, 304). The e-sync shifter element provides an e-sync signal defining an encryption state vector to the encryption algorithm block and is operable to advance the encryption state vector (in the case of the receiver) according to a number of received bits plus a variable number of bits. The variable number depends on the number of bits within a block, the maximum number of blocks that could be within a slot and the actual number of blocks within the slot.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.