Method and apparatus for synchronizing the ciphering and deciphering of binary-coded messages

US4145569A · kind A · utility

Assignee

• Gretag Aktiengesellschaft · CH

Inventor

• Kurt Ehrat · Zürich, CH

Key dates

• Filing date: Dec 22, 1964
• Grant date: Mar 20, 1979
• Expiry date: Dec 22, 1984

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04L9/12
• WIPO field: Control
• WIPO sector: Instruments

Abstract

1. A method of ciphering and deciphering binary coded messages represented by coded series of pulses comprising setting a first pulse generator to an initial condition as defined by a secret basic code and then generating under control of a first clock a first binary coded series of cipher pulses, transmitting a part of the first series of cipher pulses to a receiving station, generating at the receiving station under control of a second clock a second binary coded series of cipher pulses having a distribution identical with the first series of cipher pulses, changing at the receiving station the part of the first and a corresponding part of the second series of cipher pulses in their relative positions and forming for each of said positions over an interval of several pulses one correlation factor by multiplying together the values of the momentarily opposite simultaneous pulses of the corresponding parts of the first and second series of cipher pulses and summation of the results of said multiplications, step synchronizing with this series of correlation factors a further part of the second series of cipher pulses with a corresponding part of the first series of cipher pulses, ta…