[Cryptography] Ex-CIA Joshua Schulte Describes His Data/Crypto Hiding Prowess

[Jeremy Stanley]

On 2020-03-04 07:49:17 -0800 (-0800), Henry Baker wrote:
[...]
> The first thing I do with every new storage disk/SDcard is: dd
> if=/dev/urandom of=/dev/sdX;
> 
> Among other things, it proves to me that the new medium will
> actually hold the amount of data that it claims to be able to.
> 
> Also, I don't want somebody in the supply chain to be inserting
> porn/etc. onto my media.
> 
> (Sadly, I can't check that the SDcard microcode doesn't contain
> malware/spyware, but that's for another discussion.)
> 
> So now *all* of my slack space contains random data.
[...]

Solid state storage devices typically have some (one reference I
found suggests 7.3%) of their physical blocks hidden in reserve to
accommodate reshuffling around bad blocks and to ease transparent
wear levelling. The "physical" block addresses to which your
operating system's device driver writes aren't all the actual blocks
on the device, nor even the same actual memory locations each time
you "fill up" the ones it tells you are there.
-- 
Jeremy Stanley
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