Encrypted data transmission system employing means for randomly altering the encryption keys
US5412730A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 23, 1992 |
| Grant date | May 2, 1995 |
| Priority date | — |
| Expiry date | Apr 23, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2209/34
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A modem suitable for transmitting encrypted data over voice-grade telephone line. The modem is implemented by the combination of integrated circuit components including a microprocessor, a serial communications controller which communicates with connected data terminal equipment, and a modulator/demodulator for translating between voice band tone signals and digital data. Pseudo random number generators are employed at both the transmitting and receiving stations to supply identical sequences of encryption keys to a transmitting encoder and a receiving decoder. An initial random number seed value is made available to both stations. The random number generators are advanced at times determined by predetermined characteristics of the data being transmitted so that, after transmission has taken place, the common encryption key can be known only to the transmitting and receiving stations.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.