from a german IT magazine I got this:
https://www.heise.de/select/ct/2016/03/1454233793502849#titel_14542337935028...
openssl enc -aes-256-ctr -pass pass: "$(dd if=/dev/urandom bs=128 count=1 2>/dev/null | base64)" -nosalt < /dev/zero > /dev/sdX
I've never tested it, so I don't know if it works !
For non-german's the article sense in short:
- dd if=/dev/urandom of=/dev/sdX would need several days for 3 TB disk - the bottle leck is /dev/urandom cause it generates 15 MB/s only - to overwrite a disk there is no need to do it with a high value random number [*] - with the above command overwriting a 3 TB disk needs 5 h only
[*] the main tasks in this article is to prepare (by overwriting) a disk for encryption
P.S. in a previous contribution (Saturday, 26 January 8:52 p.m.) it should read
"(time: 500 GB *76* min)"
I looked at the wrong disk (my 320 GB disk needs more time: 112 min) !