Communications system with minimum error cryptographic resynchronization
First Claim
1. A synchronized communications system that permits resynchronization in late-entry or fade-recovery conditions, which comprises:
- a plurality of communications devices which are operative for communicating in a synchronized encrypted communications channel between each other, wherein at least one of said communications devices continuously transmits a resynchronization header comprising,a start-of-message field that includes voice or data message infotype,a message indicator field,a synchronization check field,a first error correction field computed over the start-of-message/message indicator/synchronization fields,a frame index field, anda second error correction field computed on the frame index field and wherein at least one communications device stores data of prior transmitted message indicator fields and synchronization check fields and determines late-entry and fade-recovery conditions using recently received and stored message indicator fields and synchronization check fields, and determines a late-entry condition when a received message indicator field and synchronization check field are different from the prior stored message indicator field and synchronization check field and determines a fade-recovery condition when a received message indicator field and synchronization check field are the same as the prior stored message indicator field and synchronization check field.
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Accused Products
Abstract
A synchronized communications system permits resynchronization in late-entry or fade-recovery conditions. A plurality of communications devices are operative for communicating in a synchronized, encrypted communications channel between each other. At least one of the communications devices is operative for continuously transmitting a resynchronization header that includes a start-of-message field that includes voice or data message information type, a message indicator field, a synchronization check field, a first error correction field computed over the start-of-message/message indicator/synchronization fields, a frame index field and a second error correction field computed on the frame index field. Receivers monitor the channel to decode these headers to perform late-entry or fade recovery.
33 Citations
29 Claims
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1. A synchronized communications system that permits resynchronization in late-entry or fade-recovery conditions, which comprises:
a plurality of communications devices which are operative for communicating in a synchronized encrypted communications channel between each other, wherein at least one of said communications devices continuously transmits a resynchronization header comprising, a start-of-message field that includes voice or data message infotype, a message indicator field, a synchronization check field, a first error correction field computed over the start-of-message/message indicator/synchronization fields, a frame index field, and a second error correction field computed on the frame index field and wherein at least one communications device stores data of prior transmitted message indicator fields and synchronization check fields and determines late-entry and fade-recovery conditions using recently received and stored message indicator fields and synchronization check fields, and determines a late-entry condition when a received message indicator field and synchronization check field are different from the prior stored message indicator field and synchronization check field and determines a fade-recovery condition when a received message indicator field and synchronization check field are the same as the prior stored message indicator field and synchronization check field. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of resynchronizing encrypted communications between communications devices in late-entry or fade-recovery conditions, which comprises:
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continuously transmitting a resynchronization header from one of the communications devices to another communications device, wherein the resynchronization header comprises; a start-of-message field that includes voice or data message infotype, a message indicator field, a synchronization check field, a first error correction field computed over the start-of-message/message indicator/synchronization, a frame index field, and a second error correction field computed on the frame index; and synchronizing communication between the communications devices based on a received resynchronization header by storing in at least one communications device data of prior transmitted message indicator fields and synchronization check fields and determining late-entry and fade-recovery conditions using recently received and stored message indicator fields and synchronization check fields, and further comprising determining a late-entry condition when a received message indicator field and synchronization check field are different from the prior stored message indicator field and synchronization check field and determining a fade-recovery condition when a received message indicator field and synchronization check field are the same as the prior stored message indicator field and synchronization check field. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A method of communicating, which comprises generating at a communications device a communications signal that includes a cryptographic resynchronization header that permits resynchronization in late-entry or fade-recovery conditions, wherein the cryptographic resynchronization header includes:
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a start-of-message field that includes voice or data message infotype; a message indicator field; a synchronization check field; a first error correction field computed over the start-of-message/message indicator/synchronization field; a frame index field; and a second error correction field computed on the frame index, the method further comprising transmitting the communications signal to another communications device over a synchronized encrypted communications channel, and wherein at least one communications device stores data of prior transmitted message indicator fields and synchronization check fields and determines late-entry and fade-recovery conditions using recently received and stored message indicator fields and synchronization check fields, and determines a late-entry condition when a received message indicator field and synchronization check field are different from the prior stored message indicator field and synchronization check field and determines a fade-recovery condition when a received message indicator field and synchronization check field are the same as the prior stored message indicator field and synchronization check field. - View Dependent Claims (24, 25, 26, 27, 28, 29)
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Specification