US4977596A
Expired / Lapsed
US
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Cryptographic synchronization recovery by measuring randomness of decrypted data
Assignee: United States Department of Energy
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Filing: 1989-03-15
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Granted: 1990-12-11
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Expires: 2009-03-15
Abstract
Abstract The invention relates to synchronization of encrypted data communication systems and a method which looks for any lack of pattern or intelligent information in the received data and triggers a resynchronization signal based thereon. If the encrypter/decrypter pairs are out of cryptographic synchronization, the received (decrypted) data resembles pseudorandom data. A method and system are provided for detecting such pseudorandom binary data by, for example, ones density. If the data is sufficiently random the system is resynchronized.
Inventors
- 👤 Joseph H. Maestas
- 👤 Lyndon G. Pierson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 15:55
CPC Classifications
H; H04; H04L; H04L9/00; H04L9/12
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
60 words
A method of cryptographic synchronization recovery during transmission of an encrypted digital data message comprising receiving said encrypted digital data message through an incoming data path, decrypting said digital data message, monitoring a randomness of said decrypted digital data message, and resynchronizing said incoming data path when said randomness of said decrypted digital data message falls within a predetermined range.
Claim 2
Independent Claim
60 words
A method of cryptographic synchronization recovery during transmission of an encrypted digital data message comprising receiving said encrypted digital data message through an incoming data path, decrypting said digital data message, monitoring a randomness of said decrypted digital data message, and resynchronizing said incoming data path when said randomness of said decrypted digital data message falls within a predetermined range.
Claim 3
Dependent Claim
23 words
The method of claim 1, wherein said monitoring of said randomness of said decrypted digital data message includes determining a ones density thereof.
Claim 4
Dependent Claim
18 words
The method of claim 2, wherein resynchronization is triggered when said ones density is between two threshold values.
Claim 5
Dependent Claim
21 words
The method of claim 2, wherein when resynchronization is triggered said ones density is within one of two ranges of values.
Claim 6
Dependent Claim
31 words
The method of claim 1, wherein monitoring said randomness of said decrypted digital data message includes counting an amount of ones over a predetermined length of said decrypted digital data message.
Claim 7
Dependent Claim
20 words
The method of claim 5, wherein resynchronization is triggered when said counter amount of ones is between two threshold values.
Claim 8
Dependent Claim
23 words
The method of claim 5, wherein resynchronization is triggered when said amount of counted ones is within one of two ranges of values.
Claim 9
Dependent Claim
69 words
A synchronized data communication system including data sending and data receiving units, said data means including data decrypting means for decrypting said encrypted data received from said data sending unit, said data receiving means further including means for determining the randomness of decrypted received data and for triggering a resynchronization signal to said data sending unit when said randomness of said decrypted received data falls within a predetermined range.
Claim 10
Dependent Claim
69 words
A synchronized data communication system including data sending and data receiving units, said data means including data decrypting means for decrypting said encrypted data received from said data sending unit, said data receiving means further including means for determining the randomness of decrypted received data and for triggering a resynchronization signal to said data sending unit when said randomness of said decrypted received data falls within a predetermined range.
Claim 11
Dependent Claim
60 words
The system of claim 8, wherein the means for determining the randomness of decrypted received data and for triggering a resynchronization signal includes means for determining the ones density of the decrypted received data, for comparing said determined ones density to two threshold values, and for triggering said resynchronization signal when said determined ones density is between said threshold values.
Claim 12
Dependent Claim
65 words
The system of claim 8, wherein said means for determining the randomness of decrypted received data and for triggering a resynchronization signal includes means for determining the ones density of the decrypted received data, for comparing said determined ones density to two ranges of values, and for triggering said resynchronization signal when said determined ones density is within one of said two ranges of values.
Claim 13
Dependent Claim
63 words
The system of claim 8, wherein said means for determining the randomness of decrypted received data and for triggering a resynchronization signal includes means for counting ones over a predetermined length of decrypted received data, for comparing a counted number of ones to two threshold values, and for triggering said resynchronization signal when said counted number of ones is between said threshold values.
Claim 14
Dependent Claim
69 words
The system of claim 8, wherein said means for determining the randomness of decrypted received data and for triggering a resynchronization signal includes means for counting ones over a predetermined length of said decrypted received said data, for comparing a counted number of ones to two ranges of values, and for triggering said resynchronization signal when said determined ones density is within one of said two ranges of values.
Claim 15
Dependent Claim
122 words
A means for measuring randomness of digital data having a plurality of discrete states comprising: means for counting occurrences of one of said discrete states within a predetermined length of said digital data; means for taking the ratio of said occurrences of one of said discrete states to a total number of occurrences of all of said discrete states within said digital data to determine a density of one of said discrete states within said digital data; and means for comparing said density to a plurality of preset ranges of values corresponding to said plurality of states; wherein when said density of one of said states is outside said range of values, a degree of randomness of said digital data is determined.
Claim 16
Dependent Claim
122 words
A means for measuring randomness of digital data having a plurality of discrete states comprising: means for counting occurrences of one of said discrete states within a predetermined length of said digital data; means for taking the ratio of said occurrences of one of said discrete states to a total number of occurrences of all of said discrete states within said digital data to determine a density of one of said discrete states within said digital data; and means for comparing said density to a plurality of preset ranges of values corresponding to said plurality of states; wherein when said density of one of said states is outside said range of values, a degree of randomness of said digital data is determined.
Claim 17
Dependent Claim
41 words
A means for measuring randomness of digital data having a plurality of discrete states, as in claim 13, wherein said digital data is binary, one of said discrete states is indicated by a one, and said density is a ones density.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-12-10 | 1994-06-11 | 1994-12-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-12-10 | 1998-06-11 | 1998-12-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-12-10 | 2002-06-11 | 2002-12-11 | $7700.00 | Window Closed / Lapsed |