On 07/20/2016 11:59 AM, Mohit Sethi wrote:
Dear Behcet and Pascal
I have previously reviewed the draft on address protected neighbor
discovery: draft-sarikaya-6lo-ap-nd-01.
I generally like the idea but still have some questions. I wonder what
about collisions for cryptographic IDs. The draft defines them as
64-bits long. I assume that at a minimum 80 bits are needed to assume
that it is collision free. Or is it the case that collisions are not
an issue in this case?
I just ran some numbers through for another problem with a 64bit number
field. It works out as follows.
The formula is: 1 - e^{-k^2/(2n)}
Where n is your maximum popluation size (2^64 here, 1.84E19) and K is
your actual population.
A .01% probablity of a collision is a bit less than 66M devices.
If everyone in the world has one device (7B), then you are up to a 73%
probablity of a collision.
So your risk of a collision on a network is there, but really low.
ID author, you may want to put this formula into your draft.
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