51–60 of 193 posts
forgive me if I'm naive, but can file hashes be spoofed in any way? I'm thinking upload a bunch of files that hash to random numbers, then download the de-duplicated original files. could someone more knowledgable in this area tell me if this is a credible threat?
This is the first time I've heard someone on HN actually ask for more security theatre. Sure, Dropbox could spend seven figures to get a ISOxxxx whatever consultancy to draw up a 125 page document describing their internal checks, do the obligatory all-hands yearly mandatory training where you have to get 10/10 questions right and question 1 is "A user has uploaded naked pictures of themselves to their account. True…
I might have misunderstood what you meant, but #1 is invalid. If I can look at my data any time I want, I just need the key to it. Dropbox just gives me access to the encrypted stream. Giving access to my data to someone else would therefore just be a question of sharing the key with that person, again, without Dropbox ever having access to this key. Your killer argument is to me #3. If you don't trust a company, don…
"If I can look at my data any time I want, I just need the key to it. Dropbox just gives me access to the encrypted stream."
In order for the data to be encrypted securely, you would need to generate a key on your own computer which Dropbox then uses to perform the encryption. (Tarsnap works this way.)
Forcing Drew's sister (or your mother) to generate a key would be bad for accessibility.
1. Sensationalism aside, Dropbox should review questionable security claims to reduce false sense of security if any. With millions of users, careless words formed out of marketing needs are no longer needed. What Dropbox users need now is more clear picture of what they are giving up to gain Dropbox's services.
2. The weakest security link is the user and their computer, not Dropbox which has enough financial incentives at stake to be diligent security wise. In the end, no computer open to external data or code is safe. What protect most users today is actually not security technologies but cost/benefit ratio to potential attackers, tempered by goal and scale. 99.9999% of Dropbox user data is useless to attackers and cost of mining questionable nuggets out continually expanding sea of data from 20 million users is not a trivial task.
3. While it's true that user must trust Dropbox in the end, some of its security measures could use strengthening even if it's just intended to raise the level of sophistication necessary to steal Dropbox data.
Earlier quoted context omitted.
I might have misunderstood what you meant, but #1 is invalid. If I can look at my data any time I want, I just need the key to it. Dropbox just gives me access to the encrypted stream. Giving access to my data to someone else would therefore just be a question of sharing the key with that person, again, without Dropbox ever having access to this key. Your killer argument is to me #3. If you don't trust a company, don…
Tarsnap provides exactly the sort of service you're referring to, where they only store encrypted data and don't have a copy of the key. I'm a big fan of that architecture, if only because it greatly reduces the payoff of a successful attack. When everything is stored unencrypted (or with a common master key), there's an absolutely massive payoff for the hacker who breaches the security.
Dropbox is incredibly easy to use, that's where its power comes from. It's "secure enough" for casual use.
Additionally I believe you can't share data between users with tarsnap.
There is a market opportunity for a corporate-level secure data exchange infrastructure.
The features DB offers for sharing, web access, etc. are well worth the tradeoff, and I am ashamed to see the security pedants constantly pillorying Dropbox because it's not some imaginary "verified secure" system. They don't advertise to be that. A claim of "we encrypt your files with RSA" should be utterly meaningless to you without knowledge of how the key is controlled, and a few seconds' thought and examination of the feature set should inform you that yes, Dropbox has to have the key to decrypt the files. That doesn't make the claim of "your files are encrypted" any less true.
Earlier quoted context omitted.
I might have misunderstood what you meant, but #1 is invalid. If I can look at my data any time I want, I just need the key to it. Dropbox just gives me access to the encrypted stream. Giving access to my data to someone else would therefore just be a question of sharing the key with that person, again, without Dropbox ever having access to this key. Your killer argument is to me #3. If you don't trust a company, don…
One of the reasons Dropbox is successful is because anyone can use it. Even your mother. In fact, one of the reasons Drew was originally accepted into the YC program was because his sister was using it when he applied. "If I can look at my data any time I want, I just need the key to it. Dropbox just gives me access to the encrypted stream." In order for the data to be encrypted securely, you would need to generate a…
Doable, and even better, you can make that a 30 € / month corporate option. ;)
forgive me if I'm naive, but can file hashes be spoofed in any way? I'm thinking upload a bunch of files that hash to random numbers, then download the de-duplicated original files. could someone more knowledgable in this area tell me if this is a credible threat?
and is the hashing done by the client, or server-side? because client-side would make spoofing even easier.
Earlier quoted context omitted.
de-duplication doesn't make users any more vulnerable to intrusive government actions. today, a government agency could ask any online service to provide the names of all users who have a particular file, whether or not the service employs de-duplication. and in that case, the government would also need to support its request with a warrant or court order. the rules that provide a check against unwarranted government…
To parse that, are you saying that under such a circumstance, a government agency would have to provide the names of each person they suspect have that particular file? Or could they demand the names of all users that have a particular digest of that file?
Earlier quoted context omitted.
> because they make them available to you through the web interface. You could have client side javascript that decrypts the files. http://crypto.stanford.edu/sjcl/
And where would the decryption keys come from?
Earlier quoted context omitted.
One of the reasons Dropbox is successful is because anyone can use it. Even your mother. In fact, one of the reasons Drew was originally accepted into the YC program was because his sister was using it when he applied. "If I can look at my data any time I want, I just need the key to it. Dropbox just gives me access to the encrypted stream." In order for the data to be encrypted securely, you would need to generate a…
The authentication token can be generated and managed by the software. It would then be protected by the account password, if any (Windows and MacOS X offer this feature). Doable, and even better, you can make that a 30 € / month corporate option. ;)
If the key file is not stored on Dropbox servers, then you can't easily use Dropbox across several different computers. This defeats the other purpose (accessibility).