i own a small private server (@home) with all necessary features for my backup purposes (Owncloud, SVN, GIT).

My target now is to ensure the safety of my data in emergency cases like fire/flood. For this i want to rent or use a free online cloud storage (dropbox,strato,...). My server should backup there all important data on a weekly basis. Sadly the CPU, older Atom dualcore, has not enough performance to work on heavy load tasks.

Which file format or technique should i use to upload the data in a way no other system can read it? I thought about implementing an own small crypt software for it but at first i want to here your comments.


  • By secure, do you mean to ensure the privacy or just the integrity? In the case of privacy, who do you consider an adversary (would you consider your storage provider an adversary, or just someone who might try and say compromise your account or intercept your traffic?). Are you concerned about encrypting your data at rest or just while it's being transferred?
    – thexacre
    Oct 5, 2014 at 10:29
  • Secure: I think mostly about privacy, the integrity should be handled by my storage provider. The data should be encrypted at the transfer and on the storage platform. I work on experimental things that shouldn't go public without permission. The terms of agreement from many storage provider have sections in it that they can read the files. That shouldn't happen
    – Matyro
    Oct 5, 2014 at 13:35

2 Answers 2


There are a number of providers available for this. You want to make sure that the provider you select has built in encryption options for which you can maintain the key. The below providers all support this.

Remember that you need configure the software to use an encryption key you have generated yourself and keep this secure and safe. If you lose this key your backups are gone. It might be a good idea to invest in a safe deposit box or a fire proof safe.

  • Good fire proof casings have no wire holes and problems with the heat dissipation -> You cant run a server in it. The solution to reconnect 2 HDD's on a weekly basis is not a desirable solution. How secure/trustworthy is the software of the 2 named provider, don't think its open-source.
    – Matyro
    Oct 6, 2014 at 20:24
  • 1
    @Matyro sorry, I phrased this badly. The safe was just to hold the backup of the encryption key. No power needed.
    – kronicd
    Oct 6, 2014 at 23:02

I understand the OP was asking about cloud storage; however, this answer mentions duplicity as an option in the case of something more local. The answer goes on to mention that duplicity could be used for any remote instance such as AWS on the back-end, so I feel it would be an appropriate solution to this question as well, especially if one is interested in more control over the process, the data, the ability to move around different back-ends, and the ability to survive company strategy changes such as CrashPlan's recent announcement to begin sunsetting their Home service.

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