?Que?
'dd' is good for what 'dd' is good for - no more, no less.
It will NOT fix your mail/file encryption issues. It CAN
"wipe" your old files if you use /dev/urandom or /dev/zero
as the 'source', though not against State-level probers.
Use BleachBit or multiple 'dd' passes for that. Takes a
LONG time. Better yet, disassemble your drives and
physically destroy the pretty silver platters ...... they
do make nice mobiles though ........
E-drives - you have to put a torch, or maybe a stun-gun,
to the things. The leveling algos make them basically
imposssible to erase securely. Buy a surplus neon sign
transformer, put the e-drive between the wires ....
Try to inspect "wiped" drives with 'dd' - output a number
of blocks to a file and LOOK at it with 'ghex' or something.
Anything intelligible left ? Reformatting leaves almost ALL
the old data intact - 'dd' can grab it.
"Encrypted drives" have plusses and minuses. Encryption
makes everything slower, of course. It also makes it harder
to move said drives to other machines in case of emergency.
Finally, encryption is touchy - a single bit error might make
ALL the info un-recoverable. Per-file encryption is safer, but
not as handy.