US 11,636,199 B2Granted

Real time clock with integrated anti-rollback protection

AssigneeRealtek Singapore Pte Ltd.

InventorRyan Patrick Donohue

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Abstract

A Real-Time Clock (RTC) block configured to output a current time as part of an ASIC configuration that guarantees that the RTC can never be rolled back beyond a checkpointed date and time. A checkpoint memory block is coupled to the RTC block and configured to include a stored active date/time checkpoint, and a set RTC logic block is coupled to the checkpoint memory block and to the RTC block and configured to permit setting the RTC block to an asserted new time request only when the asserted new time is in the future relative to the stored active date/time checkpoint. The active date/time checkpoint is stored in a non-volatile, single-write memory location such as in a one-time programmable (OTP) memory or in a bank of fuses so that the stored active date/time checkpoint is maintained whether or not power is interrupted to the checkpoint memory block.

Claims14

Dependent claims

An apparatus having an anti-rollback protection, the apparatus comprising:

a Real-Time Clock (RTC) block configured to output a current time;
a checkpoint memory being a non-volatile memory comprising a plurality of memory locations, each memory location being a one-time programmable memory location configured to store an active date/time checkpoint;
a checkpoint logic block coupled serially between the RTC block and the checkpoint memory block, the checkpoint logic block configured to receive an inputted checkpoint request to store a new checkpoint generated by the RTC block as a new stored active date/time checkpoint into the checkpoint memory block, only if the active date/time is larger than a previously-stored date/time, otherwise checkpoint logic does not permit the storage of the active date/time;
and
a set RTC logic block coupled serially between the checkpoint memory block and to the RTC block and configured to permit setting the RTC block to an asserted new time request only when the asserted new time is in the future compared with the stored active date/time checkpoint;
wherein the active date/time checkpoint is the date/time checkpoint most recently stored in the checkpoint memory block.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 17/227,463Filed 12 Apr 2021
Published: US 2022/0327202 A113 Oct 2022
Granted: 25 Apr 2023
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

G06F 21/54
During program execution, e.g. stack integrity ; Preventing unwanted data erasure; Buffer overflow: by adding security routines or objects to programs
G06F 1/14
Generating or distributing clock signals or signals derived directly therefrom: time supervision arrangements, e.g. real time clock
G06F 21/725
In cryptographic circuits: operating on a secure reference time value
G06F 21/575
Certifying or maintaining trusted computer platforms, e.g. secure boots or power-downs, version controls, system software checks, secure updates…:…