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I'm very interested in using an online backup service to keep my data safe from malfunctioning hardware. And I am, of course, willing to pay for the service.

However, I don't want my data to be accessible by anyone other than me - and that's including the backup service itself. The online backup services I've seen do seem to use strong cryptography for the connection to their server, and keep the data secure and encrypted on their storage space too. But I what I haven't seen advertised is giving the user an option of encrypting the data with the user's own passphrase, at the client side, so that the service provider cannot have access to the data. Well, without a quantum computer, that is.

I know I could keep my data encrypted by using an encryption software like TrueCrypt, and then back up the encrypted data storage - but I really don't want the hassle of keeping all the data on my home computer constantly encrypted. I also expect there would be some hassle from the backup process. And the whole reason for using an online backup is not having to deal with all the hassle.

Are there online backup services that:

  1. Encrypt all data with my passphrase before it gets sent to the server
  2. Use strong cryptography for the encryption
  3. Do not store or transfer my passphrase anywhere (or keep it stored strictly client-side)

I do realize if I lose my passphrase, the backup becomes useless. This is not a problem, since I'm not going to forget my passphrase. Or if I do, tough luck for me. :)

I also realize that since I'd be most likely using a proprietary software, all it takes from the software provider is an update that makes the software send my passphrase to them. The only true way to ensure privacy would be to use a known open-source software. However, I'm not worried about this risk. (By that thinking, my data is already compromized by any proprietary software I run, regardless of whether it's backup related software or not.)

The software would be mainly for Windows use, but linux support is a nice addition.

Since there are some inane restrictions for cryptographic algorithms in some parts of the world, I'll also mention that I need the service in Europe.

Similar, but not identical, topics:

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migrated from superuser.com Oct 1 '10 at 14:56

This question came from our site for computer enthusiasts and power users.

why not apply your own encryption (via GPG or the like) and drop your encrypted files into a standard service (like Dropbox or whatever)? you still have the same cons, but the pros include not being dependent on the service's software for the encryption and wider variety of services that you can use. – quack quixote Nov 19 '09 at 9:40
@quack: Because it's a hassle to do it manually, and I'd like to have a hassle-free solution. Otherwise that is a very good solution. – Ilari Kajaste Nov 19 '09 at 9:52
I would go with the scheme suggested by quack to decouple encryption from the service provider. If its encryption I want, I'll not take even their tools for the encryption. Going further, its fine even if the service provider does not honor any specific encryption -- just let them store the binary file which is made by the encryption tool of my choice. – nik Nov 19 '09 at 11:30

10 Answers 10

up vote 3 down vote accepted

SpiderOak is probably your best best. They have a zero-knowledge policy and I think they cover most of your three points. I have a review on my website if you want to take a look. Another benefit is they are cross platform. Windows, Mac and Linux and offer sync as well so you can install it on more than one machine and sync files between them. The benefits of Dropbox and Backup for the same price.

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Whoa, this one seems really good! Even the price is competitive. I'd love to read the review if you provide a link to it. – Ilari Kajaste Dec 17 '09 at 19:25
I accepted this answer just because SpiderOak is the one that I ended up using, not because I want to claim it is somehow better than the other options. (Then again, I did of course choose to use it because it seemed like the best option to me...) – Ilari Kajaste Jan 14 '11 at 18:36

Jungle Disk

(Oh well, I guess I should do some in depth research before asking a question. I have no idea how I missed this one.)

Jungle Disk uses AES-256 encryption, which gives you enterprise- level protection for your data. Since you create and control the security key, you truly control the data.

Jungle Disk is the only online storage service where the application is de-coupled from the storage and you "own" your own data. You can choose a custom AES-256 encryption key so that all of your data is encrypted before it leaves your computer, and stays encrypted while stored.

Jungle Disk uses a unique key for each file, and constructs the key using a HMAC file that helps protect against certain attacks. The master key is based on a password YOU choose, known only to you and not stored with Jungle Disk.

OS support: Windows, Mac, Linux.

Payment model: Price depends on how much space you use, no other limits.

... so, any others?

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Unfortunately JungleDisk itself is no longer available for a one-off payment; you must now pay a monthly fee just to use the product, even if the amount of stuff you backup is tiny. – romkyns Sep 28 '10 at 17:30

Have you looked at tarsnap? It's billed as "backup for the truly paranoid" :)

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Carbonite encrypts all of your data, and you can choose the key if you wish or you can let them choose it. I've been using them for several years and have been quite happy with it.

Here's a page on their help section that explains a little bit about their encryption.

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Great! They don't seem to advertise that option very much, though. Had to do some searches in their help database to find a reference to it. What about OS support, is this for Windows and Mac only? – Ilari Kajaste Nov 20 '09 at 9:49
From their site: "Carbonite supports Windows XP, Windows Vista, and Windows 7 as well as Mac OS 10.4(Tiger), 10.5 (Leopard), and 10.6 (Snow Leopard)" – Millhouse Nov 23 '09 at 17:12

Mozy lets you choose your key also. It asks you to either enter your own key or let the server generate a key at installation time.

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Great! As with Carbonite, they don't seem to advertise that option very much, it seems, but there was indeed a reference in help database. OS support seems to be for Windows and Mac only? – Ilari Kajaste Nov 20 '09 at 9:53

I would suggest looking at Wuala.

Wuala is secure storage for all your files.

Wuala is secure cloud storage, a haven in the cloud to store your files. You can safely access and share your files with friends, family, and co-workers.

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Cloudberry Backup will do that for you.

  • Encrypts with a unique key before transferring to the cloud.
  • They have versions for S3, Google Drive, Azure, Rackspace.
  • The company has a great Windows freeware client for S3 file transfer, as well.
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Backblaze does this and talks about encryption here

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I also like crashplan.com

Here is a link to the (somewhat buried) documentation about using a private encryption key.

I'd have added this link as a comment but I don't (yet) have the rep...

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I like that CrashPlan allows you to backup to a drive, take that drive to another location (friends house, whatever), set it up on their computer, and then do differential backups to that drive. It really solves that “initial full backup is too big to go over the network” problem. That part of the service is free. So, bonus. And as mentioned, the backups will be encrypted so your off-site partner can't snoop through your files.

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