Patent FR51961E successfully refreshed from Google Patents.
Patent US4549308A successfully refreshed from Google Patents.
US4549308A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Secure mobile radio telephony
Assignee: Nokia Bell Labs
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Filing: 1982-07-12
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Granted: 1985-10-22
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Expires: 2002-07-12
Abstract
Abstract An arrangement for generating an encryption key for use in encrypting communications between a mobile radio telephone unit and a base station is disclosed which can be readily changeable in real time. Each mobile unit is equipped with a machine-readable nonbroadcast code and the base station can access a translation table correlating the nonbroadcast code with the public directory number of the mobile unit. Upon changing frequencies, as for example, when a mobile unit moves from one geographical cell area to another, the current and previous frequencies or channel numbers are left to select sets of digit positions in the nonbroadcast code. The contents of these digit positions are then convolved and inserted into a modified version of the nonbroadcast code generated by convolving the original code with a shifted replica thereof. The key so generated may be used to encrypt communications for the use of any known encrypting circuitry.
Inventors
- 👤 Frank J. LoPinto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 23:17
CPC Classifications
H; H04; H04B; H04B7/00; H04B7/24; H04B7/26; H04B7/2621; H04L; H04L9/00; H04L9/08; H04L9/0861; H04L9/0891; H04W; H04W12/00; H04W12/50; H04L2209/00; H04L2209/12; H04L2209/125; H04L2209/80; H04L2209/805; H04L63/00; H04L63/06; H04L63/068
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
84 words
An arrangement for generating an encryption key for a mobile radiotelephone unit capable of utilizing any of a group of predetermined communications channel frequencies and having an original, machine-readable plural-bit nonbroadcast code, comprising: means for forming an altered version of said original machine-readable nonbroadcast code in accordance with criteria defined by communication channel frequencies utilized by said unit, and means for convolving the contents of respective bit positions of said original and said altered nonbroadcast code with each other to provide said encryption key.
Claim 2
Dependent Claim
84 words
An arrangement for generating an encryption key for a mobile radiotelephone unit capable of utilizing any of a group of predetermined communications channel frequencies and having an original, machine-readable plural-bit nonbroadcast code, comprising: means for forming an altered version of said original machine-readable nonbroadcast code in accordance with criteria defined by communication channel frequencies utilized by said unit, and means for convolving the contents of respective bit positions of said original and said altered nonbroadcast code with each other to provide said encryption key.
Claim 3
Dependent Claim
76 words
An arrangement according to claim 1 wherein said means for forming said altered version of said nonbroadcast code includes means for storing an indication of the frequency of the channel currently in use by said mobile unit and a frequency previously used by said mobile unit, means controlled by said storing means for identifying respective mutually-exclusive segments of said original nonbroadcast code, and means for convolving said segments with each other to derive a control segment.
Claim 4
Dependent Claim
35 words
An arrangement according to claim 2 wherein said means for forming said altered version of said nonbroadcast code comprises means for rotating said original nonbroadcast code in accordance with the value of said control segment.
Claim 5
Dependent Claim
159 words
An arrangement for generating an encryption key for encrypting communications between a mobile radiotelephone unit and a base station capable of communicating over any of a group of changeable communications channel frequencies, said radiotelephone unit having an original, machine-readable plural bit nonbroadcast code, comprising: means for storing an indication of a currently in-use one of said communications channel frequencies and of another of said communications channel frequencies, means responsive to each said stored indication for identifying a respective set of bit positions in said original machine-readable nonbroadcast code, means for performing a binary operation on the contents of each said set of bit positions to derive a further set of bit values, said further set being distinctive from each said set, means for providing an altered version of said machine-readable nonbroadcast code in accordance with said further set of bit values, and means for exclusively-ORing said original machine-readable nonbroadcast code with said altered version to produce said encryption key.
Claim 6
Dependent Claim
159 words
An arrangement for generating an encryption key for encrypting communications between a mobile radiotelephone unit and a base station capable of communicating over any of a group of changeable communications channel frequencies, said radiotelephone unit having an original, machine-readable plural bit nonbroadcast code, comprising: means for storing an indication of a currently in-use one of said communications channel frequencies and of another of said communications channel frequencies, means responsive to each said stored indication for identifying a respective set of bit positions in said original machine-readable nonbroadcast code, means for performing a binary operation on the contents of each said set of bit positions to derive a further set of bit values, said further set being distinctive from each said set, means for providing an altered version of said machine-readable nonbroadcast code in accordance with said further set of bit values, and means for exclusively-ORing said original machine-readable nonbroadcast code with said altered version to produce said encryption key.
Claim 7
Dependent Claim
81 words
An arrangement for generating an encryption key for use with a mobile radiotelephone unit capable of employing any of a group of communications channel frequencies, said radiotelephone unit being equipped with an original, machine-readable plural-bit nonbroadcast code, comprising: means responsive to a change in said communications channel frequencies for forming an altered version of said original plural-bit nonbroadcast code, and means for convolving said original plural-bit nonbroadcast code with said altered version of said nonbroadcast code to provide said encryption key.
Claim 8
Dependent Claim
81 words
An arrangement for generating an encryption key for use with a mobile radiotelephone unit capable of employing any of a group of communications channel frequencies, said radiotelephone unit being equipped with an original, machine-readable plural-bit nonbroadcast code, comprising: means responsive to a change in said communications channel frequencies for forming an altered version of said original plural-bit nonbroadcast code, and means for convolving said original plural-bit nonbroadcast code with said altered version of said nonbroadcast code to provide said encryption key.
Claim 9
Independent Claim
82 words
A method for generating an encryption key at a base station and at a remote unit from a respectively stored nonbroadcast code, comprising: convolving the nonbroadcast code with a shifted replica thereof to form a product, and replacing a predetermined number of bit positions in the convolved product with the result of convolving sets of predetermined bit positions defined by communication channel frequencies used in communications between said base station and said remote unit, in mutually exclusive portions of the nonbroadcast code.
Claim 10
Independent Claim
82 words
A method for generating an encryption key at a base station and at a remote unit from a respectively stored nonbroadcast code, comprising: convolving the nonbroadcast code with a shifted replica thereof to form a product, and replacing a predetermined number of bit positions in the convolved product with the result of convolving sets of predetermined bit positions defined by communication channel frequencies used in communications between said base station and said remote unit, in mutually exclusive portions of the nonbroadcast code.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-10-21 | 1989-04-22 | 1989-10-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-10-21 | 1993-04-22 | 1993-10-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-10-21 | 1997-04-22 | 1997-10-22 | $7700.00 | Window Closed / Lapsed |