any format for encrypted multimedia files?

batistuta · Veteran Joined: 29 Jul 2005 Posts: 1384 Location: Aachen

I was wondering if there is a multimedia format that supports encryption natively. In other words, I'm looking for something like saving with a password in Office documents. The idea is: when you open the file, it asks for a password and it de-encrypts in on-the-fly without the need to save it in non-encrypted form before opening.

The point is to protect some videos or pictures from someone leaving them accidentally in unencrypted form on a HD. I know that you could stream the encrypted video into a non encrypted form, re-save the images, etc. That is not the point. What I'm looking to protect is someone forgetting to delete an intermediate file (or temp stuff left behind), by using some format that does this on-the-fly in RAM. With so much multimedia around these days, I can't believe that there is no such thing for personal use but I can't find any references.

Is there such a thing? Thanks

JoeUser · n00b Joined: 08 Apr 2006 Posts: 61

Matroska appears to but I haven't tried it.
http://www.matroska.org/technical/specs/notes.html#Encryption

There's a Windows DirectShow filter for it here:
http://forum.doom9.org/showthread.php?s=&threadid=62451

But I can't find any Linux players or encoders to use it. You got me interested so I'll be looking more later. Can't do it now cause the boss spotted me slacking off Googling.

batistuta · Veteran Joined: 29 Jul 2005 Posts: 1384 Location: Aachen

I've checked your links, and they seem to go in the right direction. I wonder if there is something for linux. However, this is for audio video only... It pisses me off, because I can't find useful links (lots of trash about DRM), but I can't believe I'm the first one thinking about this.

I'm starting to think that a stacked approach like when using ecryptfs might offer a much more general solution. However, ecryptfs is quite recent, and I regard this as an old problem. Besides, I'm not sure if there is Windows and Mac support for ecryptfs yet :roll:

JoeUser · n00b Joined: 08 Apr 2006 Posts: 61

There might not be support for ecryptfs in windows but there is support for windows to mount dmcrypt and cryptoloop disks and disk image files in windows using FreeOTFE. I don't really like mounted image files though, they're not very flexible. This ecryptfs sounds interesting, I'll have to try it out and see if it's better then the EncFS/Fuse method I use now for my encryption needs.

Either way, neither of these options is without their hassles. I haven't installed ecryptfs yet but if it's like EncFS then it's not going to be easily portable if you need to share it with someone. Not like sending them an avi would and have the player prompt for a password before playing. A dmcrypt or a truecrypt file could be shared with others and mounted with a password in both Linux and Windows then it's contents read but that requires installing extra software everywhere for each person you share it with and they'd need to be familiar with using it.

There just doesn't seem to be anything available right now to password protect a multimedia file. Matroska is closest but they got a lot of work to do according to this link:

batistuta · Veteran Joined: 29 Jul 2005 Posts: 1384 Location: Aachen

I haven't tried ecryptfs, but I'm not sure why you think it won't be portable. The idea of ecryptfs is to stack it on top of any other fs. Kind of the opposite of dmcrypt, that you put it underneath a filesystem. With dmcrypt, copying a file from a filesystem to a USB stick for example would lose the encryption. With ecryptsfs you wouldn't. It is like on-the-fly encryption/decryption, but at the OS level rather than the application level. The app is not aware of the encrypted file. As I said, I have to tried it yet.

What I'm looking for (and I'm sure other people as well) is something no more complicated than saving an office document with a password. This is for sharing files with a non-technical person running Windows. Anyway... thank for your help, I'll keep looking and tell you what I find. have a nice WE

JoeUser · n00b Joined: 08 Apr 2006 Posts: 61

The brief description i read of ecryptfs made it sound like EncFS. EncFS encrypts the file names as well as the file contents. If you have many files in the directory with EncFS you'd never know one file from another to share with someone in it's encrypted state. That's why i thought it wouldn't be portable. I've just installed ecryptfs and started playing with it. On the surface it appears similar to EncFS but the filenames in the encrypted state are left unencrypted.

I tried a test where I created the encrypted data directory and a mount point in one place and made a file. Confirmed it was encrypted. Then I made a separate encrypted data directory and mount point both of different names in a different sub directory but using the same passphrase. I copied the file from the first encrypted directory to the second. Confirmed it was the encrypted file that was copied then viewed the file from the second mount point and it was usable.

So as long as the person you'd share a file with has an ecryptfs directory created with the exact passphrase they'd only need to save the file there to make it usable from what ever application they want to use but it's contents are completely encrypted to anyone else that might intercept a copy.

I like this ecryptfs

Thanks for pointing it out to me. Unfortunately there doesn't seem to be a way for windows to mount it yet. It didn't take long for someone to create something to mount dmcrypt and EncFS under windows, it probably wont be long before someone does the same here.