On Jan 14, 1:32 am, Saj TK <saj.dr...@gmail.com> wrote: > Well, what i really wanted to do is delete the Media file from the memory > location and write some encrypted data to the same location. I have to make > sure that i m writing to the same location, not anywhere else in the card.
To do this task on the removable SD card memory, you would need to unmount the filesystem, read some sectors of the filesystem directly to determine where the files are located, and write new data to the same sectors directly. I am pretty sure that none of this is do-able within Java/Android code on the dalvik VM. It would be fairly straightforward as a native Linux process, but you generally need the root of the device to create such processes, especially if other programs have access to the SD flash memory you are trying to unmount. It would be even harder to do this on the internal (system) memory, because it is where the system itself is stored, so unmounting it would basically require a specialized kernel or kernel module that could stay in RAM during the operation. This sounds like a security type of application. You mention encryption, as though you're replacing a file with its own encrypted contents. Of course, a bunch of random bytes in the same sectors would work as a secure shredder. However, SD flash memory is not all built alike, and even direct sector access is not enough to guarantee you have made the files unrecoverable. Media security is a devilishly complicated topic, and many people convince themselves they can do it effectively while many others find glaring loopholes that bypass the implementation easily. Good luck on your endeavor. I think you have a steep uphill challenge. -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
