Cryptographically secure communication system
US4283602A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 23, 1968 |
| Grant date | Aug 11, 1981 |
| Priority date | — |
| Expiry date | Sep 23, 1988 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04K1/02
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
This relates to a cryptographically secure communication system employed with an analog input, an analog output and a transmission medium each having a given low frequency pass band with a predetermined bandwidth. The input analog signal is sampled and then quantized to have an amplitude equal to one of a predetermined number of discrete amplitude levels. This quantized signal is applied together with a first sequence of signal representing randomly and with substantially equal probability the discrete amplitude levels to a modulo - M adder to encrypt the sample pulses. These encrypted sample pulses are converted to an encrypted analog signal for propagation through the transmission medium. The encrypted analog signal is received from the medium and then sampled and quantized to provide the encrypted amplitude samples at the receiver. These encrypted samples are applied together with a second sequence of signals identical to and synchronous with the first sequence of signals to a modulo - M subtractor to decrypt the received encrypted samples to recover the original analog signal samples which are then converted to an analog output signal. It is also possible to employ a modulo - M…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.