EP0119972A1
Expired / Lapsed
EP
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Apparatus for ciphering and deciphering digital messages
Assignee: Telefonaktiebolaget LM Ericsson AB
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Filing: 1984-03-06
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Granted: —
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Expires: 2004-03-06
Abstract
Abstract The invention relates to an apparatus for ciphering/ deciphering digital messages, the apparatus including a) a number of circulation registers (1-8) of which the original content of ones and zeros is predetermined by an inner key, b) means (9) for stepping the circulation registers to obtain output pulses therefrom and c) a logic unit (10) for generating a pseudo-random series based on the output pulses from the circulation registers for ciphering/deciphering the messages. In accordance with the invention, the logic unit (10) is adapted to send pseudo-random control pulsesfor modifying the normal stepping and/or content of the circulation registers (1-8).
Inventors
- 👤 Aman Kurt Arvid
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 06:35
CPC Classifications
H; H03; H03K; H03K3/00; H03K3/84; H04; H04L; H04L9/00; H04L9/06; H04L9/065; H04L9/0656; H04L9/0662; H04L2209/00; H04L2209/12
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
94 words
1 Apparatus for ciphering/deciphering digital messages and including: a) a plurality of circulation registers (1-8), of which the original content of ones and zeroes is predetermined by an inner key, b) means (9) for stepping the circulation registers to obtain output pulses therefrom and c) a logic unit (10) for generating a pseudo-random series on the basis of output pulses from the circulation registers for ciphering/deciphering the messages, characterized in that the logic unit (10) is adapted to send pseudo-random control pulses for modifying the normal stepping and/or content of the circulation registers (1-8).
Claim 2
Dependent Claim
94 words
1 Apparatus for ciphering/deciphering digital messages and including: a) a plurality of circulation registers (1-8), of which the original content of ones and zeroes is predetermined by an inner key, b) means (9) for stepping the circulation registers to obtain output pulses therefrom and c) a logic unit (10) for generating a pseudo-random series on the basis of output pulses from the circulation registers for ciphering/deciphering the messages, characterized in that the logic unit (10) is adapted to send pseudo-random control pulses for modifying the normal stepping and/or content of the circulation registers (1-8).
Claim 3
Dependent Claim
29 words
2 Apparatus as claimed in claim 1, characterized in that said control pulses are intended to affect the stepping rate of at least one of said circulation registers (1-8).
Claim 4
Dependent Claim
38 words
3 Apparatus as claimed in claim 1, characterized in that said control pulses are intended to change the polarity of at least one of the bits in at least one of said circulation registers (1-8) at pseudo-random times.
Claim 5
Dependent Claim
90 words
4 Apparatus as claimed in claim 1, characterized in that for a predetermined number of said circulation registers (1-8) each is assigned a memory register (71-78), in that said control pulses are intended to control the feeding of at least one bit from at least one of the circulation registers to the associated memory register at pseudo-random times, and in that at similarly pseudo-random times the content in at least one of the memory registers (71-78) is arranged for being fed to the associated circulation register for replacing its content.
Claim 6
Dependent Claim
29 words
5 Apparatus as claimed in claim 4, characterized in that an inverter (121-128) is adapted to invert the bits fed into the associated memory register from said circulation register.
Claim 7
Dependent Claim
24 words
6 Apparatus as claimed in claim 1, characterized in that said pseudo-random control pulses are intended for utilization during the ciphering/deciphering is in progress.
Claim 8
Dependent Claim
80 words
7 Apparatus as claimed in claim 1, an outer key being transmitted from the transmitter to the receiver side for modifying on both sides the original content of the circulation registers (1-8) to a first starting position, characterized in that said pseudo-random control pulses are intended to be utilized during the time from the first starting position (t 2 ) of the circulation registers having been taken up, until a final starting position (t 3 ) has been taken up.
Claim 9
Dependent Claim
56 words
8 Apparatus as claimed in claim 7, characterized in that a counter is arranged for being set to zero at the time for the first starting position of the circulation registers, and for it to be stepped at pseudo-random times as well as for it to start ciphering/deciphering when a given predetermined value has been reached.
Claim 10
Dependent Claim
39 words
9 Apparatus as claimed in claim 8, characterized in that the circulation registers (1-8) are adapted for switching from a first working mode to a second working mode at the time (t 3 ) of the final start position.
Claim 11
Dependent Claim
41 words
10 Apparatus as claimed in claim 9, characterized in that the circulation registers (1-8) are adapted to operate in the first working mode as direct feedback shift registers and in said second working mode as maximum-length feedback shift registers (Figure 6)
References Cited (Backward Citations)
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