What we see here is, it has a couple of serial numbers.
For example here, and here.
These tags are passive, they are extrinsic because they do need additional,
like this piece of paper or trying to be physically indented on the, on the device.
And they are non-functional because they have nothing to do
with the functionality of the chip, and most important, they are reproducible.
You can use another tag or piece of paper to over, to cover this.
Or you can change the numbers here.
And it, it is the fact that this text can be reproduced
make them unsuitable to countermeasure foundry overbuilding.
The ICID tag was proposed around 2007.
It is based on the silicon manufacturer variation.
Because these variations occur during the chip fabrication process,
and it is generally believed that they are random and uncontrollable.
Therefore, ICID is considered as an unclonable tag,
and thus can be used for anti-overbuilding.
Depending whether the ID requires additional hardware components or
not, IC Identification, or ICID, can be, can be either intrinsic or extrinsic.
Let's first see an example of
an intrinsic unclonable ICID based on leakage current.