So a secure-erase in Lion will zero-out the file itself, but there will always likely be some little cache or metadata file or saved application state that remains. And no, there is no practical way of recovering the data-not even a black ops politicorporate outfit is going to be able to recover anything useful from a high-density (say, 500GB) modern physical spinning disc after a full-scale, whole disc zero-out.Ī physical spinning disc on Lion, however, is less likely to be secure-Lion automatically saves multiple different versions of a file upon edit (and also saves images of every window ever opened and every application state) there is no way of turning off this behavior (you can turn off "app resume" itself, but the files are still written to the disc).
#Secure empty trash mac os mac os
If you really want to be secure, run your computer off of a Linux Live DVD and save all you files to a Micro-SD Card.Īs mentioned, using Mac OS 10.6 and a physical disc-based HDD, Secure Delete is perfectly legit. In order to wipe a SSD, you need a tool to send the ATA Secure Erasure command to the drive, but it will only work if the manufacture has correctly implemented it. Which brings me to Zeroing the entire drive, this will erase everything but again it only works on spinning hard drives.Īs for for SSD's that's a whole other story, but the basics of it is Securely Emptying the trash does not work, nor does Zeroing the drive.
Operating systems crap all over the disk, there is no way to be sure you've safely deleted everything. which will leave private data laying around the disk. There are also other scenarios like Versions, Time Machine Local Snapshots, Autosave, Resume, File Caches, Leftover Swap, ect. Also there OS X's defragmentation, which when it consolidates files will leave old fragments scattered around the drive. If your running a spinning hard disk drive, securely emptying the trash will 99.999% of the time get rid of the CURRENT version of the file.īut you have to keep I mind that when some applications save files, they will (non-securely) delete the old file and just save a completely new copy. If you are harbouring blueprints for some new kind of nuclear weapon and afraid the Men in Black are closing in, even tossing your hard drive in the fire may not eradicate the condemning evidence. So a single-pass is more than enough for a private sale. Again, no random citizen would ever have access to such services.ĭoes that answer your question? Secure is a relative term. Encryption, secure delete, they still retain ways to decrypt or retrieve data. Remember that government always has a key to the backdoor. These places specialize in extreme data reconstruction, from even physically damaged hard drives. No citizen would ever find themselves in contact with these kinds of outfits. To retrieve the data this fractured, you'd have to seek out special government agencies that are, by all intents and purposes, top secret. It is the DOD (Department of Defence) standard. But some data can be recovered, although reports on the net claim that the retrieval of information is scattered or broken at best.Ī 7-pass secure erase will be unrecoverable by even these firms. They can however send it to advanced security firms (and pay upwards of $5,000 USD) to retrieve the data, and even then, the success rate is low. A standard user (one like yourself) will have no means whatsoever to personally retrieve your data. A one-pass secure erase of your content is unrecoverable by any aftermarket forensic computer software.
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