CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of Korean Patent Application No. 10-2019-0068762 filed in the Korean Intellectual Property Office on Jun. 11, 2019, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

A technical field of the present disclosure relates to a hardware based detection and protection circuit which protects information in a semiconductor chip. This study is related to a semiconductor design technology for improving the robustness of in-memory computing of a mid-size research project supported by the Ministry of Science and ICT (No. 2019R1A2C301107912).

BACKGROUND ART

The contents described in this section merely provide background information on the present exemplary embodiment but do not constitute the related art.

Various physical attacks and software attacks on the semiconductor chip are threads to a product using a system on chip (SoC) or an application service using the same. Attackers perform reverse engineering on an integrated circuit and arbitrarily modify an operation mode of a circuit using acquired information or manipulate data stored in the memory.

Attackers directly access the chip to observe or analyze an internal structure by a physical invasive attack on the semiconductor chip. An attacking method includes a chip modifying method using a focused ion beam (FIB) device and a circuit modifying method using micro probe approach. The focused ion beam attacking method arbitrarily disconnects or connects a metal line using ion beam. The micro probe attacking method reads a status value of a specific metal line.

An invasive attack on a semiconductor chip causes realistic problems of hacking important data or unlocking an access security.

(Patent Document 1) Korean Unexamined Patent Application Publication No. 10-2017-0095155 (published on Aug. 22, 2017)

SUMMARY OF THE INVENTION

A main object of exemplary embodiments of the present disclosure is to detect a physical attack by a security circuit having a variable structure by changing an end of a wire of a shield to be a high impedance state.

Another object of the exemplary embodiments of the present disclosure is to detect a micro probe attack by changing a connection state of a wire by changing both ends of a wire of a shield to be a high impedance state and analyzing a test signal reflected through a connected wire path.

Another object of the exemplary embodiments of the present disclosure is to detect a focused ion beam attack by changing a connection state of a wire by changing both ends of a wire of a shield to be a high impedance state and analyzing a test signal which passes through a wire selected for every group.

Another object of the exemplary embodiments of the present disclosure is to diagnose both a micro probe attack and a focused ion beam attack by sharing and selectively controlling a tri-state buffer which changes both ends of a wire of a shield to be a high impedance state.

Another object of the exemplary embodiments of the present disclosure is to block a physical approach by changing an accessible signal path to be a high impedance state when an external attack is detected by a detection circuit.

Other and further objects of the present disclosure which are not specifically described can be further considered within the scope easily deduced from the following detailed description and the effect.

According to an aspect of the present embodiment, a security circuit includes: a shield which includes M (M is a natural number which is larger than 2) wires and is disposed above a semiconductor chip; and a detection circuit which changes a connection state of the M wires to set a wire path and analyzes a test signal traveling the wire path to detect an external attack, and the detection circuit changes an end of at least one wire of the M wires to be a high impedance state.

According to another aspect of the present embodiment, a security circuit includes: a shield which includes M (M is a natural number which is larger than 2) wires and is disposed above a semiconductor chip; and a detection circuit which changes a connection state of the M wires to set a wire path and analyzes a test signal traveling the wire path to detect an external attack, the detection circuit connects the M wires to generate a plurality of wire paths and changes of an end of the plurality of wire paths to have an impedance value so that the test signal is reflected.

According to another aspect of the present embodiment, a security circuit includes: a shield which includes M (M is a natural number which is larger than 2) wires and is disposed above a semiconductor chip; and a detection circuit which changes a connection state of the M wires to set a wire path and analyzes a test signal traveling the wire path to detect an external attack, and the detection circuit groups the M wires into K wire groups (K is a natural number which is smaller than M) and activates a wire path of a wire group selected from the K wire groups.

According to another aspect of the present embodiment, a security circuit includes: a shield which includes M (M is a natural number which is larger than 2) wires and is disposed above a semiconductor chip; and a detection circuit which changes a connection state of the M wires to set a wire path and analyzes a test signal traveling the wire path to detect an external attack, and the detection circuit changes a high impedance state of the wire path to set a first diagnosis mode which detects a micro probe attack or a second diagnosis mode which detects a focused ion beam attack.

According to another aspect of the present embodiment, a security circuit includes: a detection circuit which analyzes an output signal which passes through a plurality of wires to detect an external attack and a protection circuit which when the detection circuit detects the external attack, changes the signal path connected to a target to be protected to be a high impedance state to block the approach.

As described above, according to the exemplary embodiments of the present disclosure, a micro probe attack may be detected by changing a connection state of a wire by changing both ends of a wire of a shield to be a high impedance state and analyzing a test signal reflected through a connected wire path.

According to the exemplary embodiments of the present disclosure, a focused ion beam attack may be detected by changing a connection state of a wire by changing both ends of a wire of a shield to be a high impedance state and analyzing a test signal which passes through a wire selected for every group.

According to the exemplary embodiments of the present disclosure, both a micro probe attack and a focused ion beam attack may be diagnosed by sharing and selectively controlling a tri-state buffer which changes both ends of a wire of a shield to be a high impedance state.

According to the exemplary embodiments of the present disclosure, a physical approach may be blocked by changing an accessible signal path to be a high impedance state when an external attack is detected by a detection circuit.

Even if the effects are not explicitly mentioned here, the effects described in the following specification which are expected by the technical features of the present disclosure and their potential effects are handled as described in the specification of the present disclosure.

