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