Via PUF Technology



There are various PUF technologies, but most of them are implemented using active devices, which are sensitive to PVT (process, voltage, temperature) changes, and are accompanied by an aging effect. To overcome this, there is a problem that an ECC (Error Correction Code) logic function must be additionally introduced.
 
However, Via PUF is a technology that implements PUF by using the process deviation that occurs minutely when forming the via hole connecting the metal layers during the semiconductor production process.

This is a passive device method that is different from the existing active device method, It is an innovative method that solves all the problems of existing technologies. 


Although it is made with the same design in the same process in semiconductor production, each semiconductor chip has different characteristics because it uses fine tolerances. 
That is, different IDs are generated for each semiconductor chip. 
 This is also called the fingerprint of the semiconductor.
> Silicon Inborn ID
Via PUF is the result of a "thinking shift" that reverses the semiconductor design method taken for granted.





Although general semiconductor designs are designed for the purpose of forming via holes, via PUF is designed by choosing between the formation of via holes and non-formation of via holes.
 Accordingly, the Via PUF has unpredictable randomness (meeting the NIST SP800-90B standard), in which short and open appear half and half.
Due to the characteristics of the Via Hole, which is a passive device, it has a homeostasis that does not change its characteristics in any environment change.
Since it is indistinguishable from general Via, it has security that cannot be distinguished even with reverse engineering
[a]PUF zone at 50% probability of Via or Contact fomation
[b]Cross sectional microscopic image of VIA PUF
Root of Trust based on Via PUF



Root of Trust (RoT) refers to hardware and software-based functions that are not replicated or changed. As a system that the computer operating system (OS) is always reliable, it is characterized by stability that is not penetrated by various types of hacking attacks.

RoT cannot be achieved with SW alone, and it is important to have a HW-based RoT.
Create a Unique ID and use this random number to generate an encryption key   Root of Trust
Via PUF is the foundation of RoT, the source of all trust, by providing the characteristics of a unique Silicon Inborn ID.
Instead of injecting a unique ID from the outside, it is generated internally: improved security
Due to the characteristics of the Via Hole, which is a passive device, it has a homeostasis that does not change its characteristics in any environment change.
RoT cannot be achieved with SW alone, and 
it is important to have a HW-based RoT.
Create a Unique ID and use this random number to generate 
an encryption key     Root of Trust
Via PUF is the foundation of RoT, the source of all trust, 
by providing the characteristics of a unique Silicon Inborn ID.
Instead of injecting a unique ID from the outside, 
it is generated internally: improved security
Due to the characteristics of the Via Hole, which is a passive device, it has a homeostasis that does not change 
its characteristics in any environment change.
The table below shows the Via PUF-based RoT function and its implementation method.
Properties
RoT Function
Implementation
Uniqueness
Create a unique ID on a physical device
Via PUF
Integrity
Integrity verification function for firmware
Via PUF + asymmetric key algorithm
Execution Security
Secure firmware update
Via PUF + asymmetric key algorithm
Data Security
Secure Storage (Digital key or Certificate protection) 
Via PUF
Randomness
Unpredictable function by securing randomness
Via PUF
Encryption
Crypto Accelerator
Via PUF + encryption algorithm
Communication security
Generate private key in communication protocol
Via PUF + communication algorithm