I want to set the HDD password (in the BIOS) on my Dell Latitude C840 laptop. But before I do, I have a question. If the laptop was to fail, can I still connect the HDD to a USB hard drive adapter and get my data off it? This question is not about bypassing the password, but if the hard drive adapters are capable of handling passwords.

  • You would need to test it, but I suspect the answer is 'No'. You will need the original laptop (or its password stored in the BIOS). Not the password which you enter as HDD unlock password. This is often not the actual password sent to the HDD. – Hennes Jun 16 '13 at 14:37
  • Hmm, I was afraid of something like that. Just to be clear, I am not setting the BIOS password, but rather the BIOS gives me an option to set the HDD password. I believe it is called an ATA password. Why is it that what is sent to HDD is different from what I enter? How does the BIOS change it? Is it some kind of a hashed value? Thanks. – mcu Jun 16 '13 at 15:27
  • And back to my original question, if I know what password is actually set in the HDD, can I use a USB adapter to connect to such a drive? Does the adapter allow me to enter the password? – mcu Jun 16 '13 at 15:45
  • If it is actually set on the drive and transmitted to the drive in plain text (e.g. not encoded with a hash in the BIOS) then using an USB to SATA adater should be able to unlock the disk. You might need extra software to do that (read: you might not be able to boot from a disk which is thusly protected, but you can plug in into a running system and use ` hdparm --security-unlock PWD` to unlock the drive. Might. Untested!. – Hennes Jun 16 '13 at 15:51
  • Sometimes you can, although it may not be easy. See my answer, as it can be BIOS level, saved on the Hard Drive on a special sector, or in the firmware which varies the level of supprot. – Austin T French Jun 16 '13 at 15:51

BIOS passwords may provide zero security when it comes to stealing a computer, or moving the drive between machines.

Some implementations only prevent the BIOS from booting to the drive if a password does not match. It does not actually lock, encrypt or secure the drive itself.

If you need to remove the password, it is easy:

BIOS passwords are simple locks. If you don't provide the password, the BIOS simply stops and doesn't continue the boot process.

There are two ways to get around this simple lock:

1. Clear the BIOS/CMOS memory (usually requires direct motherboard access).

2. Remove the drive and connect it to another computer (easier).


Hennes informed me my information might be out of date, so I did some more digging:

It appears there is also the possibility that, depending on drive and system manufacturer that the drive will, in fact become locked from the password due to a special sector on the drive. These can be recovered or deleted sometimes.


It depends.

  • This is not true for all laptops (e.g. not for a Dell lattidute D series. Setting a BIOS/boot password just prevent the laptop from going past post. Also setting a HDD password made the HDD unusable on other computers). This might be shared between lattitude C series and lattutude D series) – Hennes Jun 16 '13 at 14:54
  • @Hennes you are right, I updated significantly my answer, although its much less of an answer now :D – Austin T French Jun 16 '13 at 15:04
  • "It depends" is completely correct, unfortunately...implementations vary. – Shinrai Jun 16 '13 at 15:47
  • Yeah, it looks like I might be able to use a program like MHDD to break the password. But it sure is a lot of work considering I already have a valid password, that is if the BIOS did not scramble it. – mcu Jun 16 '13 at 16:07
  • "tl;dr"? What does that mean? – Jan Doggen Jun 17 '13 at 13:14

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