Mac remembers passwords after erasing

[macbookowner]

Hello!
Do You have any idea how it's possible that Mac still remembers passwords to WiFi during reinstallation - after I successfully erased Mac OS Extended (Journaled)? It's really interesting, I thought that erasing disk with Disk Utility means that ALL data will be lost.

 

[SG-]

iCloud Keychain

 

[macbookowner]

iCloud Keychain

I have Keychain turned off. I'm talking about 7. step of this instruction: https://support.apple.com/en-us/HT201376
Installer automatically connect to my WiFi that I used before erasing computer (secure with password which should be forgotten!)

 

[Significant1]

I have Keychain turned off. I'm talking about 7. step of this instruction: https://support.apple.com/en-us/HT201376
Installer automatically connect to my WiFi that I used before erasing computer (secure with password which should be forgotten!)

The system is running from the recovery partition at the time of step 7 and not the partition you erased. So nothing strange in that. It remember from last time you where connected to WiFi in recovery. Most likely when you last installed OSX, since that is where WiFi would be needed.

 

[macbookowner]

The system is running from the recovery partition at the time of step 7 and not the partition you erased. So nothing strange in that. It remember from last time you where connected to WiFi in recovery. Most likely when you last installed OSX, since that is where WiFi would be needed.

Thanks! It's possible. Does it mean that after I erased partion, OSX still remember some personal information (ex. WiFi passwords) on on the recovery partition?

 

[Significant1]

Thanks! It's possible. Does it mean that after I erased partion, OSX still remember some personal information (ex. WiFi passwords) on on the recovery partition?

I would not call it personal data. More like configuration used during installation. E.g. interface language, keyboard-layout, network configuration etc.

WiFi password can of course be considered a bit personal.

 

[macbookowner]

I would not call it personal data. More like configuration used during installation. E.g. interface language, keyboard-layout, network configuration etc.

WiFi password can of course be considered a bit personal.

Thanks. Are there any possibilities to erase Mac completely?

 

[Significant1]

Thanks. Are there any possibilities to erase Mac completely?

Yes.
http://judeescobedo.tumblr.com/post/104225486894/how-to-remove-recovery-partition-in-mac-osx-1010
Mine has not Corestorage configured, so believe you can jump directly part 2.

But next time you want recovery. You need to boot into internet-recovery (alt+cmd+r at boot) or make a USB-recovery (https://support.apple.com/en-us/HT201372).

 

[Weaselboy]

Thanks! It's possible. Does it mean that after I erased partion, OSX still remember some personal information (ex. WiFi passwords) on on the recovery partition?

https://support.apple.com/en-us/HT204063

The Internet recovery wifi password is stored in NVRAM (firmware) and no amount of erasing the disk or erasing the recovery partition will get rid of it. After you erase the disk and do the OS reinstall, do a NVRAM reset as described at the above link and the saved wifi password will be erased from firmware.

 

[macbookowner]

Thanks a lot! All is clear to me now