Will a buyer be able to recover my files if I format my mac HD and sell it?

Question

If I follow the standard procedure for logging out and formatting my Mac before selling it, as described in https://support.apple.com/en-us/HT201065 - Will the buyer be able to recover my files with forensic software ? Who is liable if the buyer can recover personal files with sensitive information, given that I followed the instructions given by support ?

If the buyer is able to retrieve info with forensic tools - why do I almost have to be a computer scientist to understand how to sell my computer safely ?

Is a user friendly deep format too much to ask ?

Answer 1

The accepted procedure these days is that you already have FileVault enabled, right from the first time you use the Mac.

If you do, then the simple format & reinstall in Apple's instructions is totally adequate to prevent any recovery.

If you don't use FileVault, then there is no proven * method to make your data absolutely * irrecoverable.

Therefore, if you don't already use FileVault, enable it first across the entire drive. Wait until it finishes encrypting your data [may be days], then follow the simple format/install instructions.
This is not as quite * as secure as if the drive had always been encrypted, but as good as any "secure erase" procedure.
For practical purposes SSDs are safer * than HDs.

*words in italics would take 20 pages to fully explain.

Answer 2

If you have an SSD, the a simple erase should be sufficient. It is still possible to recover the data, but more difficult and expensive than for a mechanical hard drive.

There's a balance between the amount of effort, time and expense required to retrieve data, and the value of that data itself. If you don't have industrial or governmental secrets on your disk, then the chance that the buyer has specifically bought it with the intention of recovering data that can be used for profit is slim.

Answer 3

Here are a few suggestions of varying extremity:

• You can boot from an external drive, or set the Mac you are going to sell to act as a drive (hold down the "T" key while booting, and it boots in target mode), then use Disk Utility to erase the "drive". Use the Security Options to overwrite the the actual sectors on your drive. This should sufficiently obscure any resident data from most recovery methods;

• If it's a physical hard drive, you can use a commercial hard drive degausser to erase the data;

• You can replace the drive with a new one, and keep/destroy your existing one.