# The cr.yp.to microblog: 2018.03.23 00:30:38

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.

### Context

2018.03.22 23:27:09 (976948423319523328) from Daniel J. Bernstein, replying to "Frédéric Grosshans (@fgrosshans)" (976945970687741952):

Show me any allegedly "thick enough" EM shield and I'll show you a (very expensive) detector array that sees through the shield. You'll then switch to another bullshit example without admitting you were wrong, the same way that you've switched away from the Faraday-cage example.

2018.03.22 23:33:58 (976950136868925442) from "Frédéric Grosshans (@fgrosshans)":

I did not switch to antoher example: a Faraday cage and a metallic mirror are the same thing, operating through the same mechanism (conductive material wich is continuous at wavelength scale + Maxwell equations), just at different frequencies (optics vs radiowaves).

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