# The cr.yp.to microblog: 2018.03.23 02:28:44

2018.03.23 02:28:44 (976994119406014465) from Daniel J. Bernstein, replying to "Frédéric Grosshans (@fgrosshans)" (976985150469935104):

And you claim that these issues disappear when the gaps are atomic-scale? Where can I find a theorem that derives your claimed QKD non-leakage from the laws of physics without _assuming_ non-leakage? And how do you explain the evident contradiction with the holographic principle?

### Context

2018.03.22 23:53:42 (976955103587590149) from Daniel J. Bernstein, replying to "Frédéric Grosshans (@fgrosshans)" (976950136868925442):

Cages and shields are _not_ the same thing (see, e.g., https://people.maths.ox.ac.uk/trefethen/chapman_hewett_trefethen.pdf), and cages make the general QKD security issues easier to visualize. The bigger problem in this discussion is the constant switching from one bullshit claim to another.

2018.03.23 00:15:07 (976960495025565696) from "Frédéric Grosshans (@fgrosshans)":

They are the same up to quantitative difference. This paper soes not condradicts this. It shows, through a simple idealized 2d model that a Faraday cage should be modelled carefully. And a typical modern Faraday cage is closer to a metallic enclosure than to a literal cage

2018.03.23 00:30:38 (976964397104074752) from Daniel J. Bernstein, replying to "Frédéric Grosshans (@fgrosshans)" (976960495025565696):

The paper goes far beyond your characterization, as illustrated by, e.g., the paper's analysis of "the widespread misconception that the shielding is exponential" in the gap size etc.

2018.03.23 01:53:06 (976985150469935104) from "Frédéric Grosshans (@fgrosshans)":

The paper itself says "This Helmholtz equation model is highly simplified", and it indeed raises the valid point that a cage should be modelled properly, specially concerning the gaps (I actually shared the misconception Before reading the paper)