Method and system for secure telecommunications
First Claim
1. A system for insertion on a communication path between a user sending sensitive data and a receiver at a control point in said path for accepting said sensitive data, said system comprising:
- means fully located at said control point of said path for sending on said path known signals having a known on-off cadence;
means for monitoring transmission received from said user for the presence of said known signals; and
means for providing a signal representative of a possible intrusion on said line when said monitored transmission has present thereon said known signals during a known off time of said known signal cadence.
6 Assignments
0 Petitions
Accused Products
Abstract
There is disclosed a method and system for injecting a number of different signal patterns onto a tone encoded telecommunications line for the purpose of preventing unauthorized eavesdropping. The system relies upon the use of an unused column frequency of the DTMF signals and a notched filter to remove that frequency from received transmission. The second technique is the insertion of precise levels of three valid tones. A third method is the modulation of all of the tones yielding side tones which are also in the valid range, and a fourth method is by sending random signature tones on the line, thereby preventing tape recording and playback of the coded tone communcation.
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Citations
59 Claims
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1. A system for insertion on a communication path between a user sending sensitive data and a receiver at a control point in said path for accepting said sensitive data, said system comprising:
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means fully located at said control point of said path for sending on said path known signals having a known on-off cadence; means for monitoring transmission received from said user for the presence of said known signals; and means for providing a signal representative of a possible intrusion on said line when said monitored transmission has present thereon said known signals during a known off time of said known signal cadence. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A system for insertion on a communication path between a user sending sensitive data and a receiver at a control point in said path for accepting said sensitive data, and wherein said sensitive data is transmitted within a frequency spectrum, said system comprising:
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means fully located at said control point of said path for modulating any signal received at said control point; means collocated with said modulating means for retransmitting said modulated signal over said path thereby creating false information signals on said path; and means concurrently operative with said modulating means for detecting a valid signal irrespective of said modulated signal on said path. - View Dependent Claims (10, 11, 12, 13)
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14. A system for insertion on a communication path between a user sending sensitive data and a receiver at a control point in said path for accepting said sensitive data, wherein said sensitive data is transmitted at one or more of the discrete frequencies within the DTMF frequency spectrum;
- and wherein a transmission from said receiver results in a reflected transmission back to the receiver, said reflected transmission having a return loss associated therewith, said system comprising;
means at said control point for applying a plurality of discrete frequencies on said path, each such frequency being identical with a particular discrete DTMF frequency and having a known and specific power level; means, including the return loss of said communication path, for removing said applied known frequencies from said connection; means for monitoring said return loss; and means controlled by said monitoring means for disabling said applying means, when said return loss falls below a specific level.
- and wherein a transmission from said receiver results in a reflected transmission back to the receiver, said reflected transmission having a return loss associated therewith, said system comprising;
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15. A system for insertion on a communication path between a user sending sensitive data and a receiver at a control point in said path for accepting said sensitive data;
- wherein said sensitive data is transmitted at one or more of the discrete frequencies within the DTMF frequency spectrum, said system comprising;
means at said control point for applying to said communication path a frequency corresponding to one of said DTMF frequencies; and means collocated with said applying means for band- stop filtering said applied frequency from the reflected transmission from said communication path. - View Dependent Claims (16, 17)
- wherein said sensitive data is transmitted at one or more of the discrete frequencies within the DTMF frequency spectrum, said system comprising;
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18. A system for insertion on a communication path between a user sending sensitive data and a receiver at a control point in said path for accepting said sensitive data;
- wherein said sensitive data is transmitted at one or more of the discrete frequencies within the DTMF frequency spectrum; and
wherein a transmission from said receiver results in a reflected transmission back to said receiver, said reflected transmission having a return loss associated therewith, said system comprising;means at said control point for applying the following signals to said communication path; a) a signature signal having a non-DTMF frequency and a controllable cadence; b) a modulating frequency signal for modulating any detected signal to create extra transmitted frequencies; c) a plurality of discrete DTMF signals having a known power level coordinated with the loss characteristics of said communication path hybrid; and d) a frequency corresponding to a non-used one of said DTMF frequencies; means at said control point for monitoring said received signals for a comparison of transmitted signature signal cadence with said received signals; means, including the return loss of said communication connection from a user, for removing said applied known frequencies from said path; and means for band stop filtering said applied non-used DTMF frequency from the reflected transmission from said communication path. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25)
- wherein said sensitive data is transmitted at one or more of the discrete frequencies within the DTMF frequency spectrum; and
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26. A system for insertion on a communication path between a user sending sensitive data and a receiver at a control point in said path for accepting said sensitive data, and wherein said sensitive data is transmitted within a frequency spectrum, and wherein a transmission from either said sender or said sending receiver results in a reflected transmission back to the sending party, said system comprising:
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means for sending on said path one or more known signals having a known cadence; means for comparing said transmitted signal cadence with any received signal cadence; and means for providing an indication of tampering when the transmitted signal cadence does not match any received cadence. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39)
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40. A security system including:
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a user source for sending secure and non-secure information; a control system for accepting, decoding and processing said secure and non-secure information; a communication path connecting said user source and said control system, said control system including; means for sending over said communication path known signals having a known on-off cadence; means for monitoring transmission received from said user for the presence of said known signals; and means for ending communication over said path from said user to said control system when said monitored transmission contains known cadence signals during the off period of said signal cadence. - View Dependent Claims (41)
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42. A security system including:
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a user source for sending secure and non-secure information; a control system for accepting, decoding and processing said secure and non-secure information; a communication path connecting said user source and said control system, said control system including; means for modulating any signal received at said control point; means collocated with said modulating means for retransmitting said modulated signal over said path thereby creating false information on said path; and means concurrently operative with said modulating means for detecting a valid signal irrespective of said modulated signal on said path.
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43. A security system including:
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a user source for sending secure and non-secure information; a control system for accepting, decoding and processing said secure and non-secure information; a communication path connecting said user source and said control system, said control system including; means for applying a plurality of discrete frequencies on said path, each such frequency being identical with a particular discrete DTMF frequency and having a known and specific power level; means, including the return loss of said communication path, for removing said applied known frequencies from said connection; means for monitoring said return loss; and means controlled by said monitoring means for disabling said applying means, when said return loss falls below a specific level.
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44. A security system including:
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a user source for sending secure and non-secure information; a control system for accepting, decoding and processing said secure and non-secure information; a communication path connecting said user source and said control system, said control system including; means for applying to said communication path a frequency corresponding to one of said DTMF frequencies; and means collocated with said applying means for band-stop filtering said applied frequency from said communication path.
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45. A method for detecting transmission security breaches on a communication path between a user sending data and a receiver at a control point in said path for accepting said data, said method comprises the steps of:
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sending on said path known signals having a known on-off cadence; monitoring transmission received from said user for the presence of said known signals; and providing a signal representative of a possible intrusion on said line when said monitored transmission has present thereon said known signals during a known off time of said known signal cadence. - View Dependent Claims (46, 47, 48, 49)
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50. A method for detecting transmission security breaches on a communication path between a user sending data and a receiver at a control point in said path for accepting said data, said method comprises the steps of:
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modulating any signal received at said control point; retransmitting said modulated signal over said path thereby creating false information signals on said path; and detecting simultaneously with said signal modulation a valid signal irrespective of said modulated signal on said path. - View Dependent Claims (51, 52, 53, 54)
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55. A method for detecting transmission security breaches on a communication path between a user sending data and a receiver at a control point in said path for accepting said data, said method comprises the steps of:
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applying a plurality of discrete frequencies on said path, each such frequency being identical with a particular discrete DTMF frequency and having a known and specific power level; removing, via the return loss of said communication path, said applied known frequencies from said connection; monitoring said return loss; and disabling, under control of said monitoring means, said applying step when said return loss fails below a specific level.
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56. A method for detecting transmission security breaches on a communication path between a user sending data and a receiver at a control point in said path for accepting said data, said method comprises the steps of:
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applying to said communication path a frequency corresponding to a specific DTMF frequency; and band-stop filtering said applied frequency from the reflected transmission from said communication path. - View Dependent Claims (57, 58)
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59. A security system including:
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a user source for sending secure and non-secure information; a control system for accepting, decoding and processing said secure and non-secure information; a communication path connecting said user and said control system, said control system including; means for sending over said communication path a plurality of different security control signals, some of said security control signals being in-band with said secure information from said user source and some of said security control signals being a modulated version of any signal on said path; and means concurrently operative with said sending of said security control signals for extracting valid information sent from said user source regardless of said security control signals on said path.
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Specification