[Cryptography] Anonymous rendezvous (was Business opportunities in crypto)

[jrzx]

On Wednesday, May 19, 2021 11:38 AM, Natanael <natanael.l at gmail.com> wrote:
> For something like Bluetooth where you're expected to be in physical
> range to communicate (inherently limiting the signal/noise ratio and
> thus reducing risk of message flooding by malicious parties), an effective
> approach may be similar to what's been previously discussed where you
> just attempt to decrypt all headers (may work well for something like
> a laptop). Messages addressed to you would successfully decrypt.
>
> However, this is going to be energy inefficient for low power devices.

I think you are grossly over estimating the power and computational
requirements, with which modern public key systems based on variants
of curve25519 are trivial. The cost of transmitting and receiving
data over wireless is going to be enormously higher than encrypting
and decrypting it.

The scaling cost is simply the amount of data, and the amount of data
required even with very large numbers of many to many broadcasts is
small.

Suppose we have a ten thousand entities who on average change their IPs
once a day. And suppose every time they change their IP they broadcast
the new ip to the entire ten thousand, encrypted so that only a very few
people that they want to know could know. Suppose they each broadcast
once a day to five people, meaning that they broadcast and receive
fifty thousand unintellible messages every day.

That is five megabytes a day. My phone burns a gigabyte a day sitting
on the shelf.
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