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When I tried booting into recovery mode (Cmd ⌘ + R) during boot up, there's a field asking for a password. I do not know this password.

Password Screen

I am using a late-2009 21.5" iMac.

Anyone know what to do?

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So, is there someone who set the firmware password on that machine? Ask them... Or you are the only user, and somehow did it yourself accidentally? – GEdgar Jun 26 '13 at 16:13
I faintly remember doing it ages ago but I guess I forgot it. The password was definitely one of mine. – moka Jun 26 '13 at 19:52
up vote 1 down vote accepted

From the image, it looks like a Firmware password.

This bash script may be able to decrypt your firmware password, however it only works on a limited set of computers.

python -c "print ''.join(chr(int(c, 16) ^ 170) for c in '`sudo nvram security-password`'.split('%')[1:])"


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Hey! Thanks very much for the help. I already decrypted the password and managed to get into recovery mode using the tutorial here:…. Thanks again! – moka Jun 26 '13 at 17:56
@moka No problem :D You do realise that was the same link that I put in my post ;) – grgarside Jun 26 '13 at 18:01
Oh haha sorry, I didn't check the source link. Thanks again for the help. :) – moka Jun 26 '13 at 19:52

If your mac is pre 2011 then removing a strip of ram and rebooting will clear the problem. I have done this with quite a few that I have installed new systems onto and it seems to work very well. Give it a try, what have you got to lose.

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