About

This is a short howto on changing the harddrive passphrase on your ubuntu system.

It was successfully tested on

• Ubuntu Gutsy

Where is your encrypted partition?

• Have a look into /dev/mapper/. There should be an entry called ..._crypt, usually its sda5_crypt.
• Whenever I use "sda5" later on, replace it by whatever ..._crypt says in your setup.

Changing the passphrase

• You can't change the passphrase directly, add another passphrase and remove the old one.
• Passphrases are stored in "slots". So your first password is in "slot 0", the second will be in "slot 1" and so on.
• Be sure never to delete your last passphrase, or your data will be inaccessible forever.

Adding an additional passphrase

• Open a terminal, and type:

cryptsetup luksAddKey /dev/sda5

• enter the current passphrase
• enter the new/additional passphrase

Removing a passphrase

Warning: Do NOT delete the last available passphrase, or your data will be lost forever!

• To delete the first passphrase (BE SURE THERE IS A SECOND ONE! TEST THE SECOND PASSPHRASE BEFORE DELETING THE FIRST!): cryptsetup luksDelKey /dev/sda5 0

• To delete the passphrase in the second slot (BE SURE THERE IS STILL ANOTHER PASSPHRASE PRESENT!):

  cryptsetup luksDelKey /dev/sda5 1

Links

• arch wiki: Encrypted Devices Using LUKS
• LUKS - Linux Unified Key Setup

errors / ideas / contact

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