As William has noted here and earlier in this thread, there is no straight 
forward way to do sucure deletion in yaffs.

YAFFS is a log structured file system which means that a secure deletion 
requires deletion of all previous log data by forcing a gc up to the last 
data block of the file.

Assuming you're running Linux, an option would be to loop-mount a cryptfs, or 
similar, file system on top of a yaffs file. That would give you a secure 
place to store your "secrets".

On Thursday 19 October 2006 07:55, William Watson wrote:
> On 10/18/06, Peter Barada <peterb@logicpd.com> wrote:
> > One possibility is to just write zeros over all the old blocks which
> > doesn't require an erase.  Perhaps an IOCTL interface to "zap" the file
> > contents?
>
> Nice thought, but it would break the requirements of the newer NAND chips
> that pages within a block only get written in order, and only get written
> once.
> --
> wjw1961@gmail.com
> William J. Watson