US5179591A
Expired / Lapsed
US
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Method for algorithm independent cryptographic key management
Assignee: General Dynamics Mission Systems Inc
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Filing: 1991-10-16
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Granted: 1993-01-12
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Expires: 2011-10-16
Abstract
Abstract An apparatus for secure communications contains a controller for automatically selecting one of several data ciphering means utilizing one of a plurality of ciphering algorithms common to transmitting and receiving terminals. A transmitting means for transmitting encrypted data, and a receiving means for receiving encrypted data are coupled to the plurality of ciphering means. The control means automatically determines which of the ciphering means to employ for any given secure communication. The method for establishing a secure communications link includes the steps of exchanging a first message for determining a common key generation and ciphering method and comparing a further shared message for validation of communications terminal security. Additionally, the steps of trading a still further message for providing data to form traffic keys to initialize key generators, interchanging an additional message for synchronizing and verifying synchronization of secure communications between secure communications terminals, and initiating secure communication are used.
Inventors
- 👤 Douglas A. Hardy
- 👤 Leslie K. Lewis
- 👤 Barry N. Altschuler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 13:00
CPC Classifications
H; H04; H04L; H04L9/00; H04L9/12; H04L9/08; H04L9/0816; H04L9/0838; H04L9/0841; H04L9/0844; H04L2209/00; H04L2209/80
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
88 words
A method for establishing a secure communications link between first and second terminals, wherein the terminals follow a procedure including the steps of: exchanging a first message containing information on encryption devices and communications modes available within the terminals; selecting in at least one terminal a common key generation and ciphering method and a common data rate; exchanging a second message containing user authentication information; exchanging a third message for providing data to form traffic keys; exchanging a fourth message for synchronizing secure communications; and initiating secure communication.
Claim 2
Independent Claim
88 words
A method for establishing a secure communications link between first and second terminals, wherein the terminals follow a procedure including the steps of: exchanging a first message containing information on encryption devices and communications modes available within the terminals; selecting in at least one terminal a common key generation and ciphering method and a common data rate; exchanging a second message containing user authentication information; exchanging a third message for providing data to form traffic keys; exchanging a fourth message for synchronizing secure communications; and initiating secure communication.
Claim 3
Dependent Claim
34 words
A method as claimed in claim 1, wherein said first exchanging step further includes the step of: selecting a common ciphering algorithm by means of an automatic programmed hierarchy of secure information interchange methods.
Claim 4
Dependent Claim
59 words
A method as claimed in claim 1, wherein said third exchanging step further includes the steps of: generating a first random number in the first terminal; generating a second random number in a second terminal; exchanging random numbers; and forming in each terminal, a third random number from the first and second random numbers to form a traffic key.
Claim 5
Dependent Claim
18 words
A method as claimed in claim 3, wherein said forming step further includes the step of exclusive ORing.
Claim 6
Dependent Claim
77 words
A method as claimed in claim 1, wherein said fourth exchanging step further includes the steps of: encrypting a known data pattern using the information from the third exchanging step; transmitting the encrypted known data pattern; receiving an encrypted known data pattern; decrypting the received encrypted known data pattern using a traffic key derived from the third exchanging step; and comparing the decrypted received encrypted known data pattern to a stored known data pattern to determine agreement.
Claim 7
Dependent Claim
31 words
A method as claimed in claim 5, wherein said decrypting step of comparing further includes the step of decrypting a random number for use as a linear feedback shift register seed.
Claim 8
Dependent Claim
26 words
A method as claimed in claim 1, wherein said fourth exchanging step further includes the step of generating an initial linear feedback shift register seed value.
Claim 9
Independent Claim
82 words
A method for establishing a secure communications link, between terminals wherein each terminal follows a procedure comprising the steps of: exchanging an Access Domain and Capabilities Message comprising ciphering and deciphering capabilities; trading Authentication Messages comprising certified user authentication data, a certified user public key; transmitting a first Random Component Message including a first random number receiving a second Random Component Message including a second random number, and forming a traffic key; interchanging Cryptographic Synchronization messages; and initiating a secure information interchange.
Claim 10
Independent Claim
82 words
A method for establishing a secure communications link, between terminals wherein each terminal follows a procedure comprising the steps of: exchanging an Access Domain and Capabilities Message comprising ciphering and deciphering capabilities; trading Authentication Messages comprising certified user authentication data, a certified user public key; transmitting a first Random Component Message including a first random number receiving a second Random Component Message including a second random number, and forming a traffic key; interchanging Cryptographic Synchronization messages; and initiating a secure information interchange.
Claim 11
Dependent Claim
21 words
A method as claimed in claim 8, wherein said exchanging step further includes choosing a common secure information exchange ciphering algorithm.
Claim 12
Dependent Claim
33 words
A method as claimed in claim 9, wherein said choosing step further includes the step of selecting a common ciphering algorithm by means of an automatic programmed hierarchy of secure information interchange methods.
Claim 13
Dependent Claim
29 words
A method as claimed in claim 8, wherein said interchanging step further includes the step of decrypting a random number for use as a linear feedback shift register seed.
Claim 14
Dependent Claim
60 words
A method as claimed in claim 8, wherein said initiating step further includes the steps of: generating an initial linear feedback shift register value; concatenating traffic modality and initial linear feedback shift register value information; appending data of variable length to the concatenated information to form a Cryptographic Synchronization message; interchanging said Cryptographic Synchronization message; and determining a traffic modality.
Claim 15
Dependent Claim
33 words
A method as claimed in claim 12, wherein said appending step further includes the step of including unused information in the appended data to form the Cryptographic Synchronization message to a standard length.
Claim 16
Dependent Claim
21 words
A method as claimed in claim 8, wherein said transmitting step further includes the step of interchanging a traffic key variable.
Claim 17
Dependent Claim
24 words
A method as claimed in claim 8, wherein said initiating step includes the step of permitting a user to alter a chosen data rate.
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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) | 1996-01-12 | 1996-07-13 | 1997-01-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-01-12 | 2000-07-13 | 2001-01-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-01-12 | 2004-07-13 | 2005-01-12 | $7700.00 | Window Closed / Lapsed |