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Hi Guys
How Unique are the IDs generated by this API
CyGetUniqueId()
I used it in 4 of my devices and I got the response as follows:
Unique ID (64-Bit): 205942657726829
Unique ID (64-Bit): 407270913724008
Unique ID (64-Bit): 306620031729100
Unique ID (64-Bit): 424058663725010
I just want to understand if two devices are produced at the same time how different these serial numbers be. Would it be sequential or totally random? Who would be able to tell us this ?
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The ID is generated at the factory and includes information as device, fab, wafer Id, X and Y position on wafer and production date.
So the ID is unique within Cypress products.
Bob
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The ID is generated at the factory and includes information as device, fab, wafer Id, X and Y position on wafer and production date.
So the ID is unique within Cypress products.
Bob
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Thanks so much Bob I appreciate it
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I do have one more question
I see that fab and wafer id could be same for all the devices which are produced on the same day. If they are produced on the same day they would have the same production date also.
Since three parameters are same, how distinct are device ids and X and Y positions. Is it easy to guess ? I mean are x and y positions sequential enough to guess ?
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I see that fab and wafer id could be same for all the devices which are produced on the same day
The wafer ID differs from wafer towafer and on one day there is more than one wafer processed.
X and Y are the positions on the wafer.
Since you are talking about to "guess" that unique ID: what do you want to perform?
When you try to generate a secret key: Did you think about using the ID as a seed for random number generator.
Bob
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When you try to generate a secret key: Did you think about using the ID as a seed for random number generator.
[ANS] Well I wanted to use the unique id directly as the secret key, instead of using the unique id and using it as a seed to generate another secret key. Hence the concern. If there is no way someone could guess the secret key, then it is perfectly alright for me.
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You can guess any key, it is only a matter of probability. Just a bit (or byte 😉 of shuffelig the bits will decrease the risk of a "guess"
Bob