Microcircuit Wire Routing for Fault Attack Protection
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Solution Overview
Problem
Portable devices with microcircuits are vulnerable to fault attacks by light radiation and electromagnetic analysis, which require access to the active face of the microcircuit, posing a security risk as these attacks can be executed with minimal and inexpensive means, and existing countermeasures often result in damaged electrical connections during attempted resin removal.
Innovation Solution
The solution involves producing connection wires that pass above the active face of the microcircuit, allowing for controlled wire positioning and welding to create a detour path, making it difficult to remove the resin without breaking the wire, thus preventing access to the microcircuit without damaging the electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the plastic body is removed to access the active face of the microcircuit, then the attacker can perform fault attacks or EMA analysis, but the electrical connections may be damaged in the process
Solution Approach 1:
The patent applies preliminary action by pre-positioning the connection wire to pass over the active face of the microcircuit before any attack attempt occurs. This predetermined configuration ensures that any subsequent attempt to access the active face by removing the plastic body will necessarily break the wire, preventing both the attack and connection damage
Solution Approach 2:
The patent implements preliminary anti-action by configuring the connection wire to cross the active face, creating a built-in protective mechanism that actively prevents access attempts. The wire itself becomes a protective element that destroys any attempt to reach the active face, countering the attack before it can succeed
2Productivity
If connection wires follow a direct path from microcircuit pads to contact pads, then electrical connections are efficient, but the active face remains accessible to attackers
Solution Approach 1:
The patent applies curvature by making the connection wire follow a curved or bent path that passes over the active face of the microcircuit rather than a straight line. This curved trajectory positions the wire to protect the active face while still establishing electrical connection between the microcircuit pads and external contact pads
3Measurement precision
If the plastic body is completely removed to access the active zone, then electromagnetic emission measurement can be performed, but the device structure is compromised
Solution Approach 1:
The patent applies preliminary action by pre-configuring the connection wire to span across the active face before any measurement attempt. This ensures that any attempt to remove the plastic body for EMA measurement will break the wire, preventing both the measurement and structural compromise
Data Source
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AI summary
The device has a microcircuit fixed in a support whose active surface carries electric connection studs. A contact pad (e4) for external connection is arranged on the support in periphery of the microcircuit. Connection wires (w4) electrically connect the studs of the microcircuit to an external contact pad. One of the connection wires welded to an end of one of the studs of the microcircuit avoids following a direct path of the stud until the corresponding contact pad makes deviation (I4) for passing above the active surface. An independent claim is also included for a method for manufacturing a portable connectable device.