6 ms·

Show HN: Encrypted Cloud file backup

18 points by frankhissen 12y ago

sarciszewski 12y ago
Where's the source code? Creating a closed-source cryptosystem is generally a bad idea. https://en.wikipedia.org/wiki/Kerckhoffs%27s_principle 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.
- nadams 12y ago
  The whois is quite interesting as well: http://whois.domaintools.com/frankhissen.de 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.
  - wongarsu 12y ago
    >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.
TheDong 12y ago
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).
- mcdoug 12y ago
  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.
  - ryan-c 12y ago
    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.
    - StavrosK 12y ago
      Block encryption methods like XTS have their fair share of problems too: http://sockpuppet.org/blog/2014/04/30/you-dont-want-xts/ http://sockpuppet.org/blog/2014/04/30/you-dont-want-xts/
    - EmanueleAina 12y ago
      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.
      - ryan-c 12y ago
        M - N must be "large enough" and must be unpredictable, though. It might need to be pretty big.
xenophonf 12y ago
Regarding PBKDF2, you should read Colin Percival's paper on scrypt (https://www.tarsnap.com/scrypt/scrypt.pdf https://www.tarsnap.com/scrypt/scrypt.pdf).
- sarciszewski 12y ago
  Also, https://password-hashing.net/candidates.html https://password-hashing.net/candidates.html :)
- itistoday2 12y ago
  And after that, read his docs on Tarsnap itself, which seems relevant to the topic at hand: https://www.tarsnap.com/ https://www.tarsnap.com/
deleted 12y ago
[deleted]
LeoNatan25 12y ago
"Encrypted Butt file backup" Hmm... Oh, right, https://chrome.google.com/webstore/detail/cloud-to-butt-plus/apmlngnhgbnjpajelfkmabhkfapgnoai?hl=en https://chrome.google.com/webstore/detail/cloud-to-butt-plus... :-)

18 points by frankhissen 12y ago

Where's the source code? Creating a closed-source cryptosystem is generally a bad idea. https://en.wikipedia.org/wiki/Kerckhoffs%27s_principle 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.

nadams 12y ago
The whois is quite interesting as well: http://whois.domaintools.com/frankhissen.de 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.
- wongarsu 12y ago
  >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.

TheDong 12y ago

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).

mcdoug 12y ago
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.
- ryan-c 12y ago
  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.
  - StavrosK 12y ago
    Block encryption methods like XTS have their fair share of problems too: http://sockpuppet.org/blog/2014/04/30/you-dont-want-xts/ http://sockpuppet.org/blog/2014/04/30/you-dont-want-xts/
  - EmanueleAina 12y ago
    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.
    - ryan-c 12y ago
      M - N must be "large enough" and must be unpredictable, though. It might need to be pretty big.

xenophonf 12y ago

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

sarciszewski 12y ago
Also, https://password-hashing.net/candidates.html https://password-hashing.net/candidates.html :)
itistoday2 12y ago
And after that, read his docs on Tarsnap itself, which seems relevant to the topic at hand: https://www.tarsnap.com/ https://www.tarsnap.com/

deleted 12y ago

[deleted]

LeoNatan25 12y ago

"Encrypted Butt file backup" Hmm... Oh, right, https://chrome.google.com/webstore/detail/cloud-to-butt-plus/apmlngnhgbnjpajelfkmabhkfapgnoai?hl=en https://chrome.google.com/webstore/detail/cloud-to-butt-plus... :-)