secure delete flash memory, non root and other stuff

[dekatch]

hi, I'd like to discuss so called 'secure wipe' apps
I'm selling all my smartphones sooner or later and I'm most comfortable with it when i wiped my space several times

as far as I'm aware, there are lots of so called 'secure delete / wipe' apps in the playstore, which offer all the variety of secure delete.
from 'overwrite with zeros' to some 'guthman 35 passes' method

but aren't these suboptimal for flash? have heard and read, that most aren't really doing any good on flash memory.

none of the apps in the playstore offer informations about the method and the difference between physical and digital drives.

i think that is a bit misleading and also a huge gap in the playstore.

is anyone aware about the difference in secure delete between physical and digital drives and could point me to an appropriate app that also understands the difference? and maybe can even explain in help/troubleshoot section within the app? some app superior to all the spam apps?

are there app developers here on Android central?

secondly :
i am using some app atm, which says it requires root to wipe my expandable sd card storage. but i can write to that sd card without any root required. so an secure wipe app should be able to have write access as well

this is all so strange and it suggests that secure wipe apps in the playstore are rather outdated / not maintained well enough

any input is appreciated

kind regards

 

[1122334455667788]

Doesn't Android wipe all the data when you do a factory reset before selling?
Personally I'd trust Google's method more than any third party app.

With most phones being encrypted now, I think technically you only need to wipe the part of the phone that contains the decryption key.

I would be interested in what really needs to be done to wipe Flash memory. If I recall correctly, the methods in the apps you describe were designed for magnetic based drives. supposedly if you have the equipment to measure it, there is more magnetic variation than just 0/1.
Possibly Flash memory only needs one pass to be wiped?

 

[Mooncatt]

With phones encrypted now, a factory reset is all that's needed (unless you have some top secret classified info requiring physical destruction of the phone? Lol). The key is erased during the reset, so anything left is a jumbled mess.