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hi there, arash from dropbox here. all data is (as we state in the referenced help article) encrypted before it's stored on the backend. all data on dropbox ca

by arashf 15y ago

hi there, arash from dropbox here. all data is (as we state in the referenced help article) encrypted before it's stored on the backend. all data on dropbox can be made shareable and is web viewable. as a consequence, we do need the ability to decrypt in the cloud. re. employee access to files - there are controls to prevent this. for example, even drew (founder/CEO), doesn't have physical access to our storage servers anymore. for very sensitive data, there's always the option to use truecrypt (we even offer this as a recommendation in our security documentation: https://www.dropbox.com/terms#security https://www.dropbox.com/terms#security)

AndyNemmity 15y ago
What about allowing government access to files? Do you require a warrant? Under what circumstances?
- arashf 15y ago
  we take as firm as stance as possible on user privacy (google faces and fights these very issues) the government needs to comply with the provisions of the electronic communications privacy act by obtaining a warrant supported by probable cause (or in some cases a court order from a judge). these safeguards protect user privacy, even when the government is involved.
  - bradgessler 15y ago
    Assuming you store files as a combination of a hash digest function as a key and file data as a value; what controls do you have in place to handle situations where law enforcement discovers some sort of 'illegal' file data on one users account subsequently requests details on users with hash digests that match the data in that file?
    - arashf 15y ago
      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 snooping apply to online services equally, regardless of their backend architecture.
      - bradgessler 15y ago
        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?
        arashf 15y ago
        basically, the government could try to make that type of request independent of backend implementation. what protects users against such an obtrusive action (effectively violating every user's privacy in search of the bad guys) are the provisions of the electronic communications privacy act.
        bradgessler 15y ago
        Link http://en.wikipedia.org/wiki/Electronic_Communications_Privacy_Act#Summaries_of_the_decisions_about_the_act http://en.wikipedia.org/wiki/Electronic_Communications_Priva...
    - cpeterso 15y ago
      Due to Dropbox's implementation of de-duplication of identical files, any user can (in theory) determine whether (but not who) some other user is storing the same file. If you upload a file that any other user has aleady uploaded, your file transfer will be nearly instantaneous. See: "How Dropbox sacrifices user privacy for cost savings" http://paranoia.dubfire.net/2011/04/how-dropbox-sacrifices-user-privacy-for.html http://paranoia.dubfire.net/2011/04/how-dropbox-sacrifices-u...
  - otterley 15y ago
    Yes, but under the Stored Communications Act (18 U.S.C. 2703), no warrant is needed to obtain communications stored longer than 180 days. This is why encryption of data in the cloud, where the keys are not held by the provider, is essential.
huhtenberg 15y ago
What's the ETA for detailed security architecture whitepaper? "(A)ll data is encrypted before it's stored on the backend" statement is completely worthless unless (at the very least) you also describe how the keys are generated and managed.
deleted 15y ago
[deleted]
bradgessler 15y ago
Technically speaking, whats the point of encrypting data on the backend if you can decrypt it? This strikes me as a waste of computations for no real gain.
- jackowayed 15y ago
  Someone in an Amazon datacenter that gets ahold of a random backup tape/hard drive can't read it. I'm not sure if Dropbox is hosted on EC2, but if not, it means that Amazon couldn't read the data at all. (If it's hosted on EC2, Amazon could probably get ahold of the key if they really wanted to)
  - bradgessler 15y ago
    Going off of that assumption, what if the decryption keys were also stored in an Amazon data center? It is then possible for Amazon read the contents of these files. I'd like to hear from Dropbox how this works instead of speculation.
    - deleted 15y ago
      [deleted]
- msg 15y ago
  If their storage API is compromised your data isn't... you need to compromise their decryption API and the storage API. With luck the same sets of staff will not have access to both, et cetera.
itistoday 15y ago
Everything on your website that in any way addresses "Dropbox's security" should make absolutely clear the extent to which users can expect their data to be "secure". In Dropbox's case, users can expect the following: - Data is probably secure from sniffers That's it. It matters little whether "Drew has physical access to our storage servers anymore". Your code obviously has easy access to the keys used to encrypt and decrypt the data. This means all of the following scenarios are possible: - User's data is obtained via the government (users aren't necessarily even informed about this) - User's data is obtained by rouge employee (potentially leaking to _anyone_ or _anything_) - User's data is obtained by hacker (again, implies ZERO assurance of data security). So don't flash around "AES this or that" without making it absolutely clear to the average user that what you are doing is the equivalent of storing their data in a shed guarded by a lock that can be accessed by anyone who can find (or demand) the key that you've hidden under a rock somewhere.
- deleted 15y ago
  [deleted]
- arashf 15y ago
  you're right in that all these things are theoretically possible in a system where the encryption key is not stored client-side. I don't know of many services that advertise every way in which their systems could be compromised. I think you'd be hard pressed to find a company doing this. in the case of google - is there a document explaining all the places your email could end up? we believe that what we advertise is in our userbase's best interest. in theory, we could generate a lengthy document attempting to explain every possible way dropbox could be compromised. but in practice, discussing these extremely unlikely theoretical vulnerabilities would generate undue fear. as an ironic sidenote: this thread was spawned by an attempt we made to clarify our handling of court orders (see: http://www.businessinsider.com/dropbox-updates-security-terms-of-service-to-say-it-can-decrpyt-files-if-the-government-asks-it-to-2011-4 http://www.businessinsider.com/dropbox-updates-security-term... ) I say "undue fear" for a couple reasons. first and foremost because we are vigilant about making sure that user data is never compromised. our reputation would be permanently damaged if dropbox is compromised. we have a lot of smart, security conscious people making sure data in dropbox is safe. we're also listening to feedback we've been hearing from the community on things we can do to improve security. a couple concrete examples: we're working on better protecting the authentication token (config.db) so that gaining access to a dropbox account on a compromised machine is much more difficult. similarly we're working on a performant way to transmit file metadata over SSL on the mobile apps. secondly, we believe that storing data in dropbox is far more safe than the alternatives. we've designed dropbox to protect user data against threats of all kinds, but we've focused the most on helping users avoid the most common threats to their data: not having any backups at all, not having current backups, accidentally deleting files, losing hours of work, leaving files on the wrong computer, losing a USB drive with sensitive info, protecting from curious snoopers on the dorm network, etc. for all the talk of security issues in the last few weeks, we're not aware of anybody having been affected by these theoretical vulnerabilities. on the flip side, we have (literally) saved thousands of college kids from losing their theses :-).
ethankaminski 15y ago
Wait, Truecrypt? Haven't I seen warnings in the Truecrypt docs against keeping several copies of the same file? And doesn't Dropbox backup every little change? You might want to add a note on your security page that storing encrypted files on a service with automated backups, like Dropbox, may pose security risks.
- JoachimSchipper 15y ago
  Really? That'd be amazingly broken - consider any of the append-only log-structured filesystems currently in vogue on Linux, which are very likely to preserve multiple versions of any file being stored (right?). Not to mention normal backups.
- roel_v 15y ago
  How does the second part follow from the first? What is the 'security risk'?
nikcub 15y ago
A point of feedback: I know it is illegal for you to inform users if you have received a warrant for their data, but you should devise a method where a flag such as 'third party access' is set in the user preference panel to let them know that somebody has accessed the data architect this flag as part of any 'admin' access and describe it on your website - users would feel better about it if the feds know your system is designed in a way that you can't help but to inform users that data has been accessed, it might dissuade them from approaching you with warrants in the first place
- JabavuAdams 15y ago
  Interesting technical idea, but it ignores how power works. The govt will just request that they change the code so that you're in compliance.
  - nikcub 15y ago
    I poured through the laws and talked to a lawyer about it, though this was years ago. It is illegal to inform a user directly in any way, they can't make you re-architect your system to provide them a backdoor unknown to the user. also the wording can not mention 'warrant' or 'fbi' so it has to be something like 'third party access' I have been meaning to do this as a 'project' with full legal advice etc. and suggest it to google, other cloud providers Edit: found that rsync.net already do this, in a different way, as a warrant canary: http://www.rsync.net/resources/notices/canary.txt http://www.rsync.net/resources/notices/canary.txt

by arashf 15y ago

AndyNemmity 15y ago

What about allowing government access to files? Do you require a warrant? Under what circumstances?

arashf 15y ago
we take as firm as stance as possible on user privacy (google faces and fights these very issues) the government needs to comply with the provisions of the electronic communications privacy act by obtaining a warrant supported by probable cause (or in some cases a court order from a judge). these safeguards protect user privacy, even when the government is involved.
- bradgessler 15y ago
  Assuming you store files as a combination of a hash digest function as a key and file data as a value; what controls do you have in place to handle situations where law enforcement discovers some sort of 'illegal' file data on one users account subsequently requests details on users with hash digests that match the data in that file?
  - arashf 15y ago
    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 snooping apply to online services equally, regardless of their backend architecture.
    - bradgessler 15y ago
      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?
      - arashf 15y ago
        basically, the government could try to make that type of request independent of backend implementation. what protects users against such an obtrusive action (effectively violating every user's privacy in search of the bad guys) are the provisions of the electronic communications privacy act.
        bradgessler 15y ago
        Link http://en.wikipedia.org/wiki/Electronic_Communications_Privacy_Act#Summaries_of_the_decisions_about_the_act http://en.wikipedia.org/wiki/Electronic_Communications_Priva...
  - cpeterso 15y ago
    Due to Dropbox's implementation of de-duplication of identical files, any user can (in theory) determine whether (but not who) some other user is storing the same file. If you upload a file that any other user has aleady uploaded, your file transfer will be nearly instantaneous. See: "How Dropbox sacrifices user privacy for cost savings" http://paranoia.dubfire.net/2011/04/how-dropbox-sacrifices-user-privacy-for.html http://paranoia.dubfire.net/2011/04/how-dropbox-sacrifices-u...
- otterley 15y ago
  Yes, but under the Stored Communications Act (18 U.S.C. 2703), no warrant is needed to obtain communications stored longer than 180 days. This is why encryption of data in the cloud, where the keys are not held by the provider, is essential.

huhtenberg 15y ago

What's the ETA for detailed security architecture whitepaper? "(A)ll data is encrypted before it's stored on the backend" statement is completely worthless unless (at the very least) you also describe how the keys are generated and managed.

deleted 15y ago

[deleted]

bradgessler 15y ago

Technically speaking, whats the point of encrypting data on the backend if you can decrypt it? This strikes me as a waste of computations for no real gain.

jackowayed 15y ago
Someone in an Amazon datacenter that gets ahold of a random backup tape/hard drive can't read it. I'm not sure if Dropbox is hosted on EC2, but if not, it means that Amazon couldn't read the data at all. (If it's hosted on EC2, Amazon could probably get ahold of the key if they really wanted to)
- bradgessler 15y ago
  Going off of that assumption, what if the decryption keys were also stored in an Amazon data center? It is then possible for Amazon read the contents of these files. I'd like to hear from Dropbox how this works instead of speculation.
  - deleted 15y ago
    [deleted]
msg 15y ago
If their storage API is compromised your data isn't... you need to compromise their decryption API and the storage API. With luck the same sets of staff will not have access to both, et cetera.

itistoday 15y ago

Everything on your website that in any way addresses "Dropbox's security" should make absolutely clear the extent to which users can expect their data to be "secure". In Dropbox's case, users can expect the following: - Data is probably secure from sniffers That's it. It matters little whether "Drew has physical access to our storage servers anymore". Your code obviously has easy access to the keys used to encrypt and decrypt the data. This means all of the following scenarios are possible: - User's data is obtained via the government (users aren't necessarily even informed about this) - User's data is obtained by rouge employee (potentially leaking to _anyone_ or _anything_) - User's data is obtained by hacker (again, implies ZERO assurance of data security). So don't flash around "AES this or that" without making it absolutely clear to the average user that what you are doing is the equivalent of storing their data in a shed guarded by a lock that can be accessed by anyone who can find (or demand) the key that you've hidden under a rock somewhere.

deleted 15y ago
[deleted]
arashf 15y ago
you're right in that all these things are theoretically possible in a system where the encryption key is not stored client-side. I don't know of many services that advertise every way in which their systems could be compromised. I think you'd be hard pressed to find a company doing this. in the case of google - is there a document explaining all the places your email could end up? we believe that what we advertise is in our userbase's best interest. in theory, we could generate a lengthy document attempting to explain every possible way dropbox could be compromised. but in practice, discussing these extremely unlikely theoretical vulnerabilities would generate undue fear. as an ironic sidenote: this thread was spawned by an attempt we made to clarify our handling of court orders (see: http://www.businessinsider.com/dropbox-updates-security-terms-of-service-to-say-it-can-decrpyt-files-if-the-government-asks-it-to-2011-4 http://www.businessinsider.com/dropbox-updates-security-term... ) I say "undue fear" for a couple reasons. first and foremost because we are vigilant about making sure that user data is never compromised. our reputation would be permanently damaged if dropbox is compromised. we have a lot of smart, security conscious people making sure data in dropbox is safe. we're also listening to feedback we've been hearing from the community on things we can do to improve security. a couple concrete examples: we're working on better protecting the authentication token (config.db) so that gaining access to a dropbox account on a compromised machine is much more difficult. similarly we're working on a performant way to transmit file metadata over SSL on the mobile apps. secondly, we believe that storing data in dropbox is far more safe than the alternatives. we've designed dropbox to protect user data against threats of all kinds, but we've focused the most on helping users avoid the most common threats to their data: not having any backups at all, not having current backups, accidentally deleting files, losing hours of work, leaving files on the wrong computer, losing a USB drive with sensitive info, protecting from curious snoopers on the dorm network, etc. for all the talk of security issues in the last few weeks, we're not aware of anybody having been affected by these theoretical vulnerabilities. on the flip side, we have (literally) saved thousands of college kids from losing their theses :-).

ethankaminski 15y ago

Wait, Truecrypt? Haven't I seen warnings in the Truecrypt docs against keeping several copies of the same file? And doesn't Dropbox backup every little change? You might want to add a note on your security page that storing encrypted files on a service with automated backups, like Dropbox, may pose security risks.

JoachimSchipper 15y ago
Really? That'd be amazingly broken - consider any of the append-only log-structured filesystems currently in vogue on Linux, which are very likely to preserve multiple versions of any file being stored (right?). Not to mention normal backups.
roel_v 15y ago
How does the second part follow from the first? What is the 'security risk'?

nikcub 15y ago

A point of feedback: I know it is illegal for you to inform users if you have received a warrant for their data, but you should devise a method where a flag such as 'third party access' is set in the user preference panel to let them know that somebody has accessed the data architect this flag as part of any 'admin' access and describe it on your website - users would feel better about it if the feds know your system is designed in a way that you can't help but to inform users that data has been accessed, it might dissuade them from approaching you with warrants in the first place

JabavuAdams 15y ago
Interesting technical idea, but it ignores how power works. The govt will just request that they change the code so that you're in compliance.
- nikcub 15y ago
  I poured through the laws and talked to a lawyer about it, though this was years ago. It is illegal to inform a user directly in any way, they can't make you re-architect your system to provide them a backdoor unknown to the user. also the wording can not mention 'warrant' or 'fbi' so it has to be something like 'third party access' I have been meaning to do this as a 'project' with full legal advice etc. and suggest it to google, other cloud providers Edit: found that rsync.net already do this, in a different way, as a warrant canary: http://www.rsync.net/resources/notices/canary.txt http://www.rsync.net/resources/notices/canary.txt