Sutdy Of Active IC Metering For Anti-counterfeit

With the advances in semiconductor process technology,billions of transistors now can be integrated in a single die.The complexity of integrated circuit(IC)design has hence been increased dramatically.This also causes the investment in IC fabrication to increase rapidly.So lots of companies choose to outsource their IC design to other desperate foundries for fabrication.This facilitates the fabless and foundry to do what they do best.However,this also created an asymmetric IC overbuilding problem: as the owner of the design intellectual property(IP),the fabless design companies will not have the control on how many copies of their design will be fabricated by the silicon foundries while the foundry can fabricate chips of any number.In order to have a good control manufacture processing,IC metering is proposed to overcome this kind of problems.Existing IC metering techniques can be classified into passive metering or active metering.Compared to the passive metering,the active metering enables the fabless to protect his own intellectual property(IP)more efficiently and it hence attracts more interest.In this work,some new active metering methods are explored to help the fabless to protect the copyright of their designs.An improved external active metering method was first proposed.Lock was inserted on the test control(TC)port of some scan flip-flops.Without a correct key,these flip-flops cannot work normally under normal mode.Physical unclonable function(PUF)was adopted to generate a unique key for each fabricated IC.The PUF key is encrypted by public-key cryptographic(PKC)algorithm and the passed to the design house for decryption with his private key.The decrypted key was then passed to the foundry house.Only with the correct key input,can the design be unlocked and work normally.Such locking scheme will not affect the timing of the functional path.Also,this metering method allows multiple input of key friendly.After the first successful activation,the unlocking circuitry will not function any more,which overcomes the weakness of multiple queries of correct key from design house due to the variation of PUF key with environmental change or aging.The metering method just incurs acceptably low area overhead and no compromise of testability.It can resist typical attacks.This work also proposed an improved internal metering method based on a scheme of boosted finite-state machine(BFSM).The FSM of an original design is boosted with multiple pseudo initial states introduced.PUF response is used to uniquely determine the power-up state from multiple newly introduced states.The FSM was modified such that only designer knows what to input to invoke the design to transit from the power-up state to the original initial state.Solo initial state of the original design was an obvious entrance to the normal chip operation and such metering scheme was vulnerable to the attack based on bypassing all the pseudo initial states.To overcome this weakness,it was proposed to introduce extra original initial states to perplex the attacker.It is difficult for one without the knowledge of design detail to identify which is the true original initial state.Thus,he cannot easily bypass all newly introduced states and their transitions to original initial state to nullify the IC metering scheme.Little overhead is incurred while the resilience of IC metering against the invasive attack is improved.