Phys.Org: Cryptography without using secret keys

[Peter Fairbrother]

On 17/10/2019 17:43, jim bell wrote:
> Phys.Org: Cryptography without using secret keys.
> https://phys.org/news/2019-10-cryptography-secret-keys.html

Reminds me of one of the solutions to Reagan's "Trust, but Verify" 
policy: (supposedly-) unclonable speckle patterns were painted on ICBMs 
etc, and when they wanted to make sure the ICBMs were where they were 
supposed to be the inspectors shone light on them and inspected the 
return patterns.

Except the return patterns were secret - the incoming light was secretly 
chosen by the verifying party, so making forging much harder - a forger 
would either have to know the incoming light pattern and forge returns 
from those direction - perhaps possible - or have to forge a token such 
that it matched to paint from every direction, thought to be impossible.

Public speckle patterns weaken that unforgeability. Then there is the 
elephant-in-the-room problem - this is not a cipher...

"An important future application the researchers are now working on is 
secure transmission of data over a glass fiber."

Indeed.


Peter Fairbrother