Luks File Encryption Key- Use an Jpeg Image?

dman777 · 04-27-2011, 03:55 AM

I read from https://wiki.archlinux.org/index.php...ith_a_Keyfile:
keyfile.binary:

where any binary file, images, text, video could be chosen as the keyfile

If I wanted to use a JPEG picture of my cat as a key, would this be possible? How does it actually read the image?

acid_kewpie · 04-27-2011, 04:00 AM

it doesn't read the image, it reads a countably random stream of data.

dman777 · 04-27-2011, 06:13 AM

So to confirm, the the jpeg has it's own set stream of data that is read, correct?

acid_kewpie · 04-27-2011, 06:22 AM

no you're not getting it. it's just data, nothing here cares in anyway whatsoever what the file is, it just reads it. It doesn't know it's an image, it doesn't have any interest in interpreting the file correctly at all. it's just gobbledygook to be used as an encryption hash, and lots of it...

nomb · 04-27-2011, 09:26 AM

Yea so what acid_kewpie is saying is that you point LUKS at a file, doesn't matter which and LUKS will read say the first 1MB of that file. Picture, music, movie, it doesn't matter. Either way the first 1MB is read and that is your key. I'm not saying it does read the first 1MB I'm just saying it reads a chunk of data from any file. That chunk of data is your key. If your file changes, and that chunk of data in the file changes, it will no longer work as a key.

acid_kewpie · 04-27-2011, 09:37 AM

Quote:

Originally Posted by nomb

Yea so what acid_kewpie is saying is that you point LUKS at a file, doesn't matter which and LUKS will read say the first 1MB of that file. Picture, music, movie, it doesn't matter. Either way the first 1MB is read and that is your key. I'm not saying it does read the first 1MB I'm just saying it reads a chunk of data from any file. That chunk of data is your key. If your file changes, and that chunk of data in the file changes, it will no longer work as a key.

What if I have two pictures of my cat? Will they both work? What if he gets bigger in one of them or has a different colour collar on?

nomb · 04-27-2011, 10:02 AM

If the data read from both files are the same, then they both should work.
If the data read from both files is different, then only one will work.
If they are different you could add the other to another key slot and then they both would work.

Ansikt · 04-27-2011, 01:55 PM

Please, acid_kewpie, explain how "the jpeg has its own set stream of data that is read" is "not getting it at all," because as far as I can tell, that's a perfectly apt description. But thanks for the condescension!