Not quite. There is no shortage of bad ideas in this Discussion, but you can find a handful of rational explanations that illustrate the reason "secure empty trash" was removed.
To fully appreciate the reasons requires understanding the various methods in which files are stored. If it were as simple as your example — repetitiously writing "zeros" (or any random data, for that matter) to magnetic media using a known file storage system — then reasonable assurance of irrecoverable data destruction could be provided. But it's not that simple. Electrically erasable memory and its flash implementation does not use magnetic domains in physical locations, so there is no benefit to changing their charge state any more than just once. The problem with repetitious rewriting is that flash memory has a finite number of write / erase cycles. It's a very large number, but it's still finite. Therefore flash memory requires a variety of techniques to ensure that all its cells are utilized more or less equally, to maximize its useful life.
Forget about flash memory and SSDs for now though, those reasons have been beaten to death. What about traditional hard disk drives? Can't Apple implement "secure empty trash" for people whose Macs still use them? Again the answer is not that simple. Hard disk drives are not write-cycle limited, but they suffer from other failure modes that cause entire sectors to eventually become unreliable. Firmware that controls hard disk drives automatically detects those failed sectors and prevents them from being used, writing data to sectors that remain usable. What happens to those "bad" sectors? Good question. Whatever data they contained remains, permanently inaccessible to the higher level devices that used to be able to write to and subsequently read from those sectors — including, you guessed it — "secure empty trash". Data recovery equipment and methods exist to circumvent that firmware and retrieve that "secure" data. They're expensive and time-consuming to use, but it illustrates one reason "secure empty trash" was little more than a placebo even for traditional hard disk drives. The general public might learn more about that in some upcoming Congressional testimony. Probably not though.
It gets worse. What about "fusion drives" that combine a traditional spinning hard disk with flash memory? Good question. What gets stored, and where? Fusion Drives used by Apple control that in their own firmware, again beyond the reach of OS X's ability to assure irrecoverable data destruction should that be desired.
Had enough yet? What happens when someone decides to build his own "fusion drive" from any generic hard disk and SSD (it's not difficult) and retrofit that to a Mac, either internally or otherwise. They don't have the benefit of Apple's proprietary firmware controlling them. Should a "secure empty trash" option be provided for them, knowing full well that it could not possibly assure irrecoverable data destruction?
Heard enough yet? There's more. What about all those third party kernel extensions that allow a Mac user to write to NTFS formatted drives, that otherwise can't be done with OS X? Good question. What about other file storage systems, that don't even permit overwriting of files (they exist)? Should Apple provide "secure empty trash" for every possible implementation of file storage systems completely beyond their control? Could they even do that? Is it even Apple's business to know how their customers choose to store their files anyway? Maybe Apple should simply eliminate the ability to alter the kernel. I surmise that would raise a lot more ire than this pathetic subject. Be careful what you ask for.
If Apple provides a method in OS X to "securely" delete files their customers have a reasonable expectation that it should do exactly that. For them to retain it knowing it can't reliably accomplish what their customers expect of it would be irresponsible.
Scroll back and read the posts by NBW and R C-R including the links they provided. There are others and I do not mean to omit anyone in particular. What is surprising to me is the degree to which people demand their placebo — which is all "secure empty trash" ever was. Unfortunately I now foresee an entire cottage industry of opportunistic App Store developers selling 99¢ utilities to wrap a GUI around srm and accompany it with clever cartoon animations and "shredder" sound effects, preserving the illusion. Those things are very popular and really lucrative. Don't forget advertisement revenue.
The original reply to this Discussion remains the most viable option for anyone working with secure documents: "If you are working with sensitive files whose content must be secure from unauthorized access, use FileVault." It has always been so, well before Apple decided to remove "secure empty trash".
kohls
Level 1
(18 points)
kohls
