Indistinguishable Shield Tracks for IC Security
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Solution Overview
Problem
Integrated circuit chips are vulnerable to physical and electrical attacks, such as live hardware analysis and reverse engineering, which can compromise their security, especially in secure circuits like smart cards, as existing passive and active shielding methods can be defeated by advanced techniques like Focused Ion Beam modification.
Innovation Solution
The integration of indistinguishable active and passive conductive tracks within the power grid of the chip, where the active shield tracks are made of the same material and arranged in a similar layout to the passive tracks, making them visually indistinguishable, and connected to detection circuits to detect and counter alterations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If passive shields (metallic planes or tracks) are used to protect against physical attacks, then physical shielding is provided, but the shields can be defeated by deviating tracks or ineffective tolerance thresholds
Solution Approach 1:
The patent merges active shield tracks and passive power grid tracks into a single hybrid structure. Both types of tracks share the same physical layer and are made of identical conductive material, making them visually indistinguishable. This combination allows the system to maintain the protective function of active shields while avoiding the vulnerability of separate passive shields that can be easily targeted and modified by FIB attacks.
Solution Approach 2:
The patent creates visual copies of power grid tracks using active shield tracks. The active shield tracks are designed to exactly replicate the appearance, material composition, and layout patterns of passive power grid tracks. This copying strategy confuses attackers who cannot distinguish which tracks are functional power distribution and which are protective shields, thereby preventing targeted FIB modifications.
2Measurement precision
If active shields with random bit sequences are used to detect alterations, then detection capability is improved, but the shields can be defeated by FIB if track functions are known
Solution Approach 1:
The patent applies local quality by making each track's function (active shield or passive power grid) invisible at the local visual level. Individually, each track appears identical to its neighbors, with no distinguishable features revealing its true function. The differentiation only becomes apparent through electrical measurement, not visual inspection. This local homogeneity prevents attackers from identifying and targeting specific shield tracks for FIB modification.
Solution Approach 2:
The patent enforces complete homogeneity between active shield tracks and passive power grid tracks. Both are fabricated using the same conductive material (e.g., copper or aluminum), the same layer deposition process, and the same geometric dimensions. This material and structural homogeneity ensures that optical microscopes, electron microscopes, and other observation devices cannot distinguish between shield and power tracks, thereby protecting the active shield configuration from targeted attacks.
3Reliability
If separate active and passive shield layers are implemented, then protection functionality is provided, but manufacturing complexity and cost increase
Solution Approach 1:
The patent implements universality by making the conductive tracks serve multiple functions simultaneously. The same physical track structure functions both as power distribution (passive role) and as an active shield (protective role), depending on which type of track it is. This multi-functionality eliminates the need for separate dedicated shield layers and power grid layers, reducing manufacturing complexity while maintaining both protection and power distribution functionalities.
Solution Approach 2:
The patent combines what would traditionally be separate manufacturing processes into a single integrated process. Instead of fabricating distinct active shield layers and passive power grid layers at different stages, both types of tracks are created together in the same fabrication step using identical materials and processes. This merging of manufacturing operations simplifies production, reduces the total number of layers, and lowers manufacturing costs while preserving the dual functionality of power distribution and security protection.
Data Source
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AI summary
An integrated circuit chip and a method for protecting the integrated circuit chip against physical and/or electrical alterations are disclosed. The chip comprises at least one semiconductor layer including semiconductor components and conductive tracks, at least one layer formed by a first type of conductive tracks extending over all or part of a surface of the chip and at least one second type of conductive track connected to at least one detection circuit configured to detect an alteration of the at least one second type of conductive track. The chip is characterized in that the at least one first type of conductive track is mixed within the at least one second type of conductive track, the material and the layout of at least one second type of conductive track being indiscernible, by an observation device, from the material and the layout of the at least one first type of conductive track.