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FIELD-PROGRAMMABLE CALL-STATUS INDICATOR

IP.com Disclosure Number: IPCOM000130440D
Publication Date: 2005-Nov-11
Document File: 1 page(s) / 26K

Publishing Venue

The IP.com Prior Art Database

Abstract

A common request in security conscious sites is a means for identifying whether a mobile device is currently in a voice call, so that information may not be covertly sent. To be implemented properly and securely, this status indicator must be a hardware means, and provide for evidence of tampering. For those reasons, it has generally been considered that a separate device SKU would be required. However the demand for such a device would not be very high (in the hundreds of thousands) so the extra SKU was not considered worthwhile. This invention provides a means for a field-programmable version of the hardware that would be built exactly the same as a non-secure device, with the user or a third party instigating a one-time event that cannot be undone, to initiate the ability to provide the status indicator. In addition this method could be incorporated fairly inexpensively (estimated < USD$2.00 per unit) The idea centers around a hardware implementation of the following logic: if (Microphone_ON AND FuseLink_Blown) then LED_Status_True The FuseLink would be tied to the microprocessor for initiating of the fuse being blown, and for verification that the event had happened successfully. The FuseLink would also be integral to some hardware that would activate an external indicator, ie an LED. As a practical indication of how this may be done, the AD5171 is an I2C programmable, One Time Programmable Digital potentiometer. Its value is set by the microprocessor over the I2C serial bus and permanently set into fusible links. This device also provides verification to the Microprocessor that the value has been set. The output of this potentiometer could then be compared, via a comparator, to the microphone bias signal. The output of this comparator could then be used to drive a transistor in a WIRED_OR configuration with the LED, alowing other signals to drive the LED also. The whole circuit could then be potty with epoxy before or after manufacture, to provide the tamper proof evidence.

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FIELD-PROGRAMMABLE CALL-STATUS INDICATOR


A common request in security conscious sites is a means for identifying whether a mobile device is currently in a voice call, so that information may not be covertly sent. To be implemented properly and securely, this status indicator must be a hardware means, and provide for evidence of tampering. For those reasons, it has generally been considered that a separate device SKU would be required. However the demand for such a device would not be very high (in the hundreds of thousands) so the extra SKU was not considered worthwhile.
This invention provides a means for a field-programmable version of the hardware that would be built exactly the same as a non-secure device, with the user or a third party instigating a one-time event that cannot be undone, to initiate the ability to provide the status indicator. In addition this method could be incorporated fairly inexpensively (estimated < USD$2.00 per unit)
The idea centers around a hardware implementation of the following logic:
if (Microphone_ON AND FuseLink_Blown) then LED_Status_True
The FuseLink would be tied to the microprocessor for initiating of the fuse being blown, and for verification that the event had happened successfully.
The FuseLink would also be integral to some hardware that would activate an external indicator, ie an LED.
As a practical indication of how this may be done, the AD5171 is an I2C programmable, One Time Programmable Digital potentiometer. Its value is set...