Re: transferring large encrypted images.
Selva Nair schreef: If the backup is from an encrypted volume to another, depending on the scheme used, you could arrange rsync to see only decrypted data (with the transport protected by, say, ssh): for example, both destination and source using eCryptfs could have the decrypted volumes mounted during the backup. Hmmm, I know, but it would be like mounting the image within for instance a block container (I would create a block container the size of my quotum, and hope I can run LUKS or TrueCrypt there). Then you mount that container and then store the images/volume in there, and that then effectively is the volume's encryption. But I do not like that scheme. The image itself is already a form of a block container. Mounting it would be pointless (it is not really a file-level container, more like block-level). But this may not be necessary: Directly backing up an encrypted volume could still make use of rsync's delta algorithm:.in case of eCryptfs, for example, data is encrypted in blocks of page_size (e.g., 4kB), so only a few blocks may change during updates and subsequent rsync runs could be almost as efficient as on unencrypted volumes -- I haven't tested this though. That's what I mentioned. It depends on whether the encryption algorithm "randomizes" the encryption runs to make them different each time, or not. Because if they are the same, you could use --rsyncable on gzip and then what you say would be correct. But in practice, thus far (I haven't tested it extensively with what I'm currently using) you get a different encryption each run, which means all the blocks are different. If encryption is only to protect the data during transport, you can simply use ssh transport with rsync. Ya but it is more for remote storage (and even local storage, there are different levels of "having to give up your passwords" and you may have to give up one (your first) but you may still be in the position to keep your seconds or thirds. I have had a scheme where I had at least 3 different sets of passwords and I can at my own leisure, so to speak, hand over the first when I feel like it, and they will see an almost empty system except that all normal applications are there -- just no email etc. Then, there is another password and it only reveals non--offensive stuff. I mean, what to call it. Non-controversial. So when they get the second password they see only stuff that is not very important. And then the 3rd password is even a hidden partition. Stuff like that. I only forgot the password to the outer volume :P. lol :(. If the idea is to protect the data at a remote backup destination, say on the cloud, rsync may not be the best option. For that I prefer duplicity which uses the rsync algorithm to transfer only deltas (uses librsync) but stores the backup as tar archives encrypted by GnuPG (both the initial full backup as well as incremental deltas). You lose the advantage of a mirror archive that rsync can maintain. So duplicity is a full solution. Meaning, probably, that it transfers the data unencrypted or temporarily-encrypted, and then encrypts it at the remote host with the given solution? All of these schemes require some process running at the remote host. This is also a (part) Windows solution I need. That is to say, either the software encrypts the image, or I do it myself. You can do a cat over ssh but that obviates the ability to have incremental stuff, probably, unless you devise it really well. You could then encrypt it remotely as it is received, but that is not really what you want either. I mean partial transfers, or retranfers, or continuation of tranfers. The only real solution for what I want is to have a delta on the encrypted blocks. So given that that is not possible, you delta the unencrypted file but encrypt it remotely. However, that doesn't work with the solution I'm using. It would also imply you directly store the file remotely, not storing it locally first. All impossible, to day. You probably cannot even mount a block device / file unless you are root. So yeah, I don't know yet. Thanks for the thought though, I will think about it. Thanks, B. -- Please use reply-all for most replies to avoid omitting the mailing list. To unsubscribe or change options: https://lists.samba.org/mailman/listinfo/rsync Before posting, read: http://www.catb.org/~esr/faqs/smart-questions.html
Re: transferring large encrypted images.
Paolo Bolzoni schreef: Why are you encrypting the files and not the filesystem and the channel? Because of what the other person mentioned. If anything anywhen gets compromised, people may have access to the filesystem(s) and the channel(s) before they get access to the file. That is to say, yes it is a remote host with a form of cloud suppliance. I do not think that I can encrypt that filesystem. Of course, I could encrypt it on the spot but then rsync would also not work. They might take my private key from somewhere, so to speak (that does the transfer) but then they still won't have the file. The local filesystem is encrypted, not one of the others. I mean I see the advantage technically but practically having an encrypted file is way superior for me. They are images, so they are like filesystems themselves. It is a filesystem that is being stored on a filesystem. That's why I encrypt the image. And I store them on remote hosts that I do not control. Regards, X. -- Please use reply-all for most replies to avoid omitting the mailing list. To unsubscribe or change options: https://lists.samba.org/mailman/listinfo/rsync Before posting, read: http://www.catb.org/~esr/faqs/smart-questions.html
Re: transferring large encrypted images.
On Tue, Oct 13, 2015 at 12:54 PM, Xen wrote: > Hi Folks, > > I was wondering if I could ask this question here. > > Initially when I was thinking up how to do this I was expecting block > encryption to stay consistent from one 'encryption run' to the next, but I > found out later that most schemes randomize the result by injecting a > random block or seed at the beginning and basing all other encrypted data > on that. > > In order to prevent plaintext attacks I guess (the block at the beginning > of many formats is always the same?) and also to prevent an attacker from > learning the key based on multiple encryptions using the same key. > > However the downside is that any optimization scheme is rendered useless, > such as rsync's. > > What is a best practice for this, if any? > If the backup is from an encrypted volume to another, depending on the scheme used, you could arrange rsync to see only decrypted data (with the transport protected by, say, ssh): for example, both destination and source using eCryptfs could have the decrypted volumes mounted during the backup. But this may not be necessary: Directly backing up an encrypted volume could still make use of rsync's delta algorithm:.in case of eCryptfs, for example, data is encrypted in blocks of page_size (e.g., 4kB), so only a few blocks may change during updates and subsequent rsync runs could be almost as efficient as on unencrypted volumes -- I haven't tested this though. If encryption is only to protect the data during transport, you can simply use ssh transport with rsync. If the idea is to protect the data at a remote backup destination, say on the cloud, rsync may not be the best option. For that I prefer duplicity which uses the rsync algorithm to transfer only deltas (uses librsync) but stores the backup as tar archives encrypted by GnuPG (both the initial full backup as well as incremental deltas). You lose the advantage of a mirror archive that rsync can maintain. Selva -- Please use reply-all for most replies to avoid omitting the mailing list. To unsubscribe or change options: https://lists.samba.org/mailman/listinfo/rsync Before posting, read: http://www.catb.org/~esr/faqs/smart-questions.html
Re: transferring large encrypted images.
Why are you encrypting the files and not the filesystem and the channel? On Tue, Oct 13, 2015 at 6:54 PM, Xen wrote: > Hi Folks, > > I was wondering if I could ask this question here. > > Initially when I was thinking up how to do this I was expecting block > encryption to stay consistent from one 'encryption run' to the next, but I > found out later that most schemes randomize the result by injecting a random > block or seed at the beginning and basing all other encrypted data on that. > > In order to prevent plaintext attacks I guess (the block at the beginning of > many formats is always the same?) and also to prevent an attacker from > learning the key based on multiple encryptions using the same key. > > However the downside is that any optimization scheme is rendered useless, > such as rsync's. > > What is a best practice for this, if any? > > My backup software that I'm currently using, I'm on Windows, does encryption > but since it has the key, it can create differentials/incrementals so the > whole image does not need to be retransferred. If it works, but that's > another story. > > Still, differentials and incrementals are all fine (grandfather, father, > son) but updating the/a main full image file itself would perhaps be much > more efficient still. > > For some reason my host and rsync on Windows are rather slow, I get some > 500K/s upload for a 20GB file. Which takes, kinda long. > > I might start splitting the files in lower gigabyte chunks as well, though. > > Currently sending it to another host at 1MB/s which rsyncs it to the real > target where I'm less concerned about how long it takes. > > But I'm sending it over with scp (pscp) because for some reason rsync is > also rather slow here (maybe it's my computer). > Scp has no partial option (how silly) but I can just rsync if it fails. > > Still, I wonder how other people are doing this, if they do something like > this. > > Regards, > > Xen. > > > -- > Please use reply-all for most replies to avoid omitting the mailing list. > To unsubscribe or change options: > https://lists.samba.org/mailman/listinfo/rsync > Before posting, read: http://www.catb.org/~esr/faqs/smart-questions.html -- Please use reply-all for most replies to avoid omitting the mailing list. To unsubscribe or change options: https://lists.samba.org/mailman/listinfo/rsync Before posting, read: http://www.catb.org/~esr/faqs/smart-questions.html
