Enforcing time-based transaction policies on devices lacking independent clocks

A method for operating a device, that does not have a local time clock that provides a measure of time on power-up of the device, to enforce a transaction policy requiring a reliable time reference, comprising:

• establishing a secure communications channel to each of one or more network attached time sources using a procedure selected from the set including:
• establishing a TLS channel to a dedicated network server having a non-expiring digital certificate, establishing a channel with a dedicated network server using a symmetric key with the dedicated network server, establishing a channel with a general purpose time server for obtaining a value of current time from the general purpose time server, and establishing a channel with a host compute to which the device is connected for obtaining a value of current time from the host computer to which the device is connected, wherein the dedicated network server is deployed to provide time service to a class of devices to which the device that does not have a local time clock that provides a measure of time on power-up of the device belongs;
• obtaining a current time value from each of the one or more network attached time sources;
• assigning a reliability index to the current time value received from each of the one or more time-sources;
• using the received current time value from each of the one or more network attached time sources and the reliability index associated with each received current time value to estimate a current time value and to calculate a reliability index associated with that the estimated current time value;
• and
• using the estimated current time value and the calculated reliability index to permit or deny permission for certain time sensitive transactions.

A method for operating a device that does not have a local time clock that provides a measure of time on power-up to enforce a transaction policy requiring a reliable time reference, comprising:

• establishing a communications channel to each of one or more network attached time sources using a procedure selected from the set including:
• establishing a TLS channel to a dedicated network server having a non-expiring digital certificate, establishing a channel with a dedicated network server using a symmetric key with the dedicated network server, establishing a channel with at least one general purpose time server for obtaining a value of current time from the at least one general purpose time server, and establishing a channel with a host computer to which the device is connected for obtaining a value of current time from the host computer to which the device is connected, the dedicated network server is deployed to provide time service to a class of devices to which the device that does not have a local time that provides a measure of time on power-up of the device belongs;
• obtaining a current time value from each of the one or more network attached time sources;
• assigning a reliability index to the current time received from each of the one or more time-sources as a function of which procedure was used to obtain the current time from such time source;
• estimating a current time from the obtained current time value from each of the one or more network attached time sources and calculating a reliability index associated with the estimated current time from the reliability index assigned to each of the received current time values;
• and
• using estimated current time and the calculated reliability index to permit or deny permission for certain time sensitive transactions.

A device, that does not have a local time clock that provides a measure of time on power-up of the device, that is capable of enforcing a time-based transaction policy that requires a reliable time reference, comprising:

• a central processing unit;
• a memory connected to the central processing unit and comprising:
• a time-agent computer program having instructions to cause the central processing unit to:
• establish a secure communications channel to one or more network-attached time sources;
• inquire each of the one or more network-attached time-sources as to the current time using the communications channel;
• receive the current time from the one or more network-attached time-sources wherein at least one of the one or more network-attached time source is a dedicated time server deployed to provide time service to a class of devices to which the device not capable of independently maintaining a local time clock belongs;
• and
• estimate the current time from the received current time from each of the one or more network-attached time sources and to calculate a reliability index associated with the estimated current time and a reliability index associated with each of the one or more network-attached time sources;
• and
• a policy-agent computer program having instructions to cause the central processing unit to:
• use the estimated current time and the calculated reliability index to enforce the time-based transaction policy.