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Show HN: Encrypted Cloud file backup

frankhissen.de

18 pointsfrankhissen13 comments

I've been looking for a good truecrypt replacement, but this unfortunately isn't it (yet at least).

1) Closed source. I can't take security software seriously without the source code.

2) Windows only. Ditto for the above

3) There's no point in encrypting a folder with N files to result in N encrypted files. It's always more cryptographically sane to create a large block of data (as truecrypt did) rather than reveal information about how many inputs there were and allow people to correlate them.

Those three issues mean I won't be using this (especially the open source bit).

Exactly what I was going to say with 1 & 2. Your point #3 is arguable. It's more secure to encrypt a block than files, but it's not always nearly as convenient. You wouldn't want to sync a multi GB block to S3 every time it changes. You have to encrypt filenames, and pad the files, but file-level encryption has its uses.

Knowing the approximate file sizes and number of files in a directory, especially with further context of overall directory structure can allow someone to guess what the content is with high probability if the files are "well known". Consider a directory containing pirated episodes of a tv show, organized with a subdirectory per season. "Scene releases" tend to have one a few possible approximate file sizes, and depending on how much padding, it may be enough information to identify a set of files as all being scene releases of the same show. Many other examples like this - anything "popular" that's will have a fingerprint of extracted file sizes.

Block encryption methods like XTS have their fair share of problems too: http://sockpuppet.org/blog/2014/04/30/you-dont-want-xts/

You can also encrypt N files yielding M > N blocks, to avoid much of the issues you described while still avoiding the one-large-blob concern.

M - N must be "large enough" and must be unpredictable, though. It might need to be pretty big.

Where's the source code? Creating a closed-source cryptosystem is generally a bad idea.

https://en.wikipedia.org/wiki/Kerckhoffs%27s_principle

> You may not distribute or redistribute this software without permission.

This is a turn-off. MIT/BSD/GPL/WTFPL licensing is more likely to gain rapport with hackers than non-free software.

> The keyfile is secured by a password using PKCS #5 (PBKDF2) with a SHA512/Whirlpool based HMAC using 100000 iterations and also AES and Twofish.

This sentence makes me greatly question the implementation of this system and now I really want to see the source code before I even think of trusting it for any reason. PBKDF2 is generally performed with ONE hash function and doesn't require block ciphers at all.

The whois is quite interesting as well: http://whois.domaintools.com/frankhissen.de

If I'm reading that right - it says that 1&1 are the owners of the domain.

Yikes - and it looks like he is distributing a version of Java with it.

>If I'm reading that right - it says that 1&1 are the owners of the domain.

German domains should be looked up directly at denic.de for best results. Owner and admin-c of the domain is Frank Hißen. 1&1 is tech-c and zone-c, but not owner.

Regarding PBKDF2, you should read Colin Percival's paper on scrypt (https://www.tarsnap.com/scrypt/scrypt.pdf).

Also, https://password-hashing.net/candidates.html :)

And after that, read his docs on Tarsnap itself, which seems relevant to the topic at hand: https://www.tarsnap.com/

"Encrypted Butt file backup"

Hmm...

Oh, right, https://chrome.google.com/webstore/detail/cloud-to-butt-plus... :-)

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