Faster disk erase

Faster disk erase.txt

openssl enc -aes-256-ctr -pass pass:"$(dd if=/dev/urandom bs=128 count=1 2>/dev/null | base64)" -nosalt < /dev/zero | pv -pterb -s $(blockdev --getsize64 /dev/sdb) | sudo dd bs=4M of=/dev/sdb

Thanks to https://serverfault.com/questions/6440/is-there-an-alternative-to-dev-urandom/415962

Note per https://tches.iacr.org/index.php/TCHES/article/view/8392 it may not be as secure as one might dream, but I'm OK with this given my use.

This lets me write to the disk at 128MiB/s, which is better than the ~20MiB/s I was getting when doing the naive

cat /dev/urandom | pv | sudo dd of=/dev/sdb

Probably the `dd` was using a tiny buffer, but there's also no need for random data as high quality as urandom in this case.

Faster still:

dd if=/dev/urandom bs=8192 count=1 | tr -d '\000' | dd if=/dev/stdin bs=4095 count=1 of=4095.rand

sudo bash -c 'yes `cat 4095.rand` > /dev/sdb'

This breaks iotop :( but oh well.

Confirm with hexedit that it finished properly, then zero-out the first 1MB.
Note that this breaks iotop :(