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OweFS – One-way encrypted file system

owefs.firelet.net

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Re: OweFS – One-way encrypted file system

#21

Post by timmclean »

Sir_Cmpwn wrote: post #16
timmclean wrote: post #9

Heads up to anyone considering using this: the author wrote their own crypto code[1]. I would recommend against using this until that is fixed... I've already spotted a few vulnerabilities. [1] https://github.com/FedericoCeratto/owefs/blob/master/pycrypt...

I don't necessarily disagree, but at some point the buck has to stop, right? How would you implement this any other way? The author didn't implement AES or so on himself, he uses standard library encryption and applies it as appropriate. You should probably report the issues you find to federico.ceratto-at-gmail.com (from Github).

The author should use a library that provides a simple "encryptWithPublicKey" method, so that any choices about RSA key size, AES mode of operation, etc are all taken care of. NaCl[1] would probably be best, since it's written and audited by prominent cryptographers.

[1] http://nacl.cr.yp.to/

Re: OweFS – One-way encrypted file system

#23

Post by FiloSottile »

timmclean wrote: post #9

Heads up to anyone considering using this: the author wrote their own crypto code[1]. I would recommend against using this until that is fixed... I've already spotted a few vulnerabilities. [1] https://github.com/FedericoCeratto/owefs/blob/master/pycrypt...

For a start, it's not authenticating ciphertexts: it uses plain hybrid RSA-AES-CFB

Re: OweFS – One-way encrypted file system

#25

Post by kentonv »

FiloSottile wrote: post #23
timmclean wrote: post #9

Heads up to anyone considering using this: the author wrote their own crypto code[1]. I would recommend against using this until that is fixed... I've already spotted a few vulnerabilities. [1] https://github.com/FedericoCeratto/owefs/blob/master/pycrypt...

For a start, it's not authenticating ciphertexts: it uses plain hybrid RSA-AES-CFB

To be fair, most full-disk encryption schemes do not authenticate.

Re: OweFS – One-way encrypted file system

#27

Post by xrcltr »

Sir_Cmpwn wrote: post #16
timmclean wrote: post #9

Heads up to anyone considering using this: the author wrote their own crypto code[1]. I would recommend against using this until that is fixed... I've already spotted a few vulnerabilities. [1] https://github.com/FedericoCeratto/owefs/blob/master/pycrypt...

I don't necessarily disagree, but at some point the buck has to stop, right? How would you implement this any other way? The author didn't implement AES or so on himself, he uses standard library encryption and applies it as appropriate. You should probably report the issues you find to federico.ceratto-at-gmail.com (from Github).

There are a tremendous number of other ways this could be implemented.

Authenticated encryption? GCM? XTS? Salt the CFB? Guard against interblock attacks?

The crypto needs to be completely reworked. This is an asymmetric kek around symmetric encryption, which is done in many other projects.

Half-backed crypto such as this is worse than no crypto at all, as it lulls people into believing they are using a valid cryptographic system. But, the project implements (poorly) a subset of what is needed and pushes the rest into application code - but app writers don't know this and wouldn't know what to implement even if they know of the shortcomings.

Cryptographers see this all the time. People think they invented a new concept but only implemented a well-known design but did it incompletely and with well-known flaws in the crypto. Then, people defend the system, when it would be far easier to use better primitives.

Re: OweFS – One-way encrypted file system

#28

Post by xrcltr »

kentonv wrote: post #25
FiloSottile wrote: post #23

Earlier quoted context omitted.

For a start, it's not authenticating ciphertexts: it uses plain hybrid RSA-AES-CFB

To be fair, most full-disk encryption schemes do not authenticate.

This is not disk encryption. This is file encryption.

Re: OweFS – One-way encrypted file system

#29

Post by doomrobo »

pliu wrote: post #12
doomrobo wrote: post #3

Exposing filenames in the clear like that is a significant drawback. I'm not sure how you could get around it, though.

Linux 4.1+ with ext4 supports filesystem level encryption, and it encrypts filenames. The implementation seems very complex, I'm not sure how mature this feature is. I think the state is probably "not production ready", but I don't know very much about this. http://blog.quarkslab.com/a-glimpse-of-ext4-filesystem-level... https://docs.google.com/document/d/1ft26lUQyuSpiu6VleP70_npa...

This can't be used for assymetric encryption. The reason you can still see files and filenames on normally encrypted drives is because your OS holds the encryption key AND decryption key in memory (they're actually the same because it's using symmetric encryption). The problem with the assymetric case is that you no longer have the decryption key, so if you encrypt a filename, you don't get to refer to the file anymore, of course unless (as another user commented) you encrypt the filename you're using to reference the file every time you reference the file, which isn't a terrible idea.

Re: OweFS – One-way encrypted file system

#30

Post by marbu »

lotyrin wrote: post #19
Sir_Cmpwn wrote: post #16

Earlier quoted context omitted.

I don't necessarily disagree, but at some point the buck has to stop, right? How would you implement this any other way? The author didn't implement AES or so on himself, he uses standard library encryption and applies it as appropriate. You should probably report the issues you find to federico.ceratto-at-gmail.com (from Github).

You could make this a frontend to an existing system like GPG

It looks like OP has that in the roadmap. Unfortunately it also seems that the last work has been done in 2013.
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