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I have got a backfile with extension .tar.gz.enc. After fooling around I found out that it is encrypted gzipped tarball.

Now I want know how to decrypt it.

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up vote 3 down vote accepted

If you don't know the encryption algorithm and the keys, well ... you're screwed (mostly).

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well I know it mostly :D what I'm interested in is the part that is left outside mostly. – TheVillageIdiot Mar 15 '11 at 19:50
Well, the other side of the "mostly" is to try guessing the algorithm and do some cryptologic attack on that particular algorithm (dedicated or brute force). The possibilities are very broad... so I would not count on that. I do not know, but it may exists some software that tries encryption cracking and/or identifying. But basically if the original owner took enough precautions... it tends to be impossible to succeed now. – M'vy Mar 15 '11 at 19:56

I encrypt my backups with

openssl aes-256-ecb -e -a -salt -in backup.tar.gz -out backup.tar.gz.enc

And decrypt then the same way (just replace -e with -d). Openssl asks me for a passphrase, and without that passphrase, nobody will ever (say, in the next 15 years) decrypt the archive.

So,yeah, you're screwer unless you know the passphrase. If you do, try different openssl commands and maybe one will work.

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You are assuming the asker uses OpenSSL for encryption. – grawity Mar 16 '11 at 12:28
I'm just saying this is a possibility, and emphasizing that nothing can be done without the passphrase. – Julien Vehent Mar 16 '11 at 16:01

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