[1] https://github.com/FedericoCeratto/owefs/blob/master/pycrypt...
I have no intention to mislead any user into running it so I'll remove the repository for the time being.
That doesn't immediately mean that the library is useless.
> until that is fixed
I disagree with the word "fixed", as if it's broken. He probably used the highest-level primitives he could to achieve the requirements.
> I've already spotted a few vulnerabilities.
It'd probably be more constructive to open an issue detailing the vulnerabilities rather than saying "I've spotted some, use NaCl" and leaving it at that. What makes you so sure that NaCl is even a suitable replacement without knowing all the considerations that went into the project?
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.
I doubt eight bytes is enough for cryptography...
If you need random bytes in Python, use os.urandom:
secret = os.urandom(32)
Pretty sad if it is not the case! Interestingly enough, RNG in pycryptodome which I was using for zerodb is urandom. https://github.com/Legrandin/pycryptodome/blob/master/lib/Cr...
Would be interesting to see similar gotchas about that library (though everybody uses PyCrypto, that makes me feel a little paranoid!)
http://blog.quarkslab.com/a-glimpse-of-ext4-filesystem-level...
https://docs.google.com/document/d/1ft26lUQyuSpiu6VleP70_npa...
(So you have public key 0xDEAFBEEF; you want to write a file named 'secret.txt' with the contents 'We attack at dawn'. OweFS encrypts 'We attack at dawn' to 010101 and writes that to 'secret.txt'. But why couldn't it have encrypted the contents to 010101 and encrypted the filename 'secret.txt' to 111000, and then written a file named 111000.encrypted with the contents 010101? Then when the owner of 0xDEAFBEEF wanted to read it, he simply decrypts 111000.encrypted to 'secret.txt' and decrypts its content 010101 to 'We attack at dawn.')
Firstly, let's assume that directories aren't encrypted. Otherwise this would be a real PITA - just to locate /foo/bar/baz.txt you'd have to decrypt each component of 001001/011101/110101.encrypted separately.
More importantly, the decrypting software has no way to encrypt things, only decrypt them. So to read 'secret.txt' you can't just encrypt 'secret.txt' to '111000.encrypted'. Instead, you have to iterate through the entire directory listing and decrypt every single filename, until you find one that decrypts to 'secret.txt'.
Obviously this gets pretty bad with even moderately-sized directories. I assume this is why the project doesn't encrypt filenames.
http://www.techrepublic.com/blog/linux-and-open-source/creat...
why not use the asymmetric keypair to guard an AES key, and use AES to do the encryption instead, something like what https is doing.
"Every time a new file is being written, owefs_encrypt creates a one-time random key. The random key is encrypted using the public key and is embedded in the new file. The contents of the file are encrypted using such random key."
> Some files may need to be written while the device is locked. A good example of this is a mail attachment downloading in the background. This behavior is achieved by using asymmetric elliptic curve cryptography (ECDH over Curve25519). The usual per-file key is protected by a key derived using One-Pass Diffie-Hellman Key Agreement as described in NIST SP 800-56A.
> The ephemeral public key for the agreement is stored alongside the wrapped per-file key. The KDF is Concatenation Key Derivation Function (Approved Alternative 1) as described in 5.8.1 of NIST SP 800-56A. AlgorithmID is omitted. PartyUInfo and PartyVInfo are the ephemeral and static public keys, respectively. SHA-256 is used as the hashing function. As soon as the file is closed, the per-file key is wiped from memory. To open the file again, the shared secret is re-created using the Protected Unless Open class’s private key and the file’s ephemeral public key; its hash is used to unwrap the per-file key, which is then used to decrypt the file.
The two applications that caught my eye were "home security cameras" (which the docs allude to) and secure telemetry.
You have a device (say, a drone) that logs telemetry data, but if the drone is lost, the data cannot be recovered by a third party without the private key.