Guys, don't confuse the crypto issues here. The whole point to tarsnap is to be able to safely encrypt any and all of your data, including compressed data. We

Guys, don't confuse the crypto issues here. The whole point to tarsnap is to be able to safely encrypt any and all of your data, including compressed data. We wouldn't expect that a .tar.gz being backed up is somehow "less secure" than the .tar file, we'd demand the same security for both. Compression becomes a problem when it can be used as an "oracle" into the key used for a given stream of ciphertext. The reason TLS is susceptible is because the attacker can MITM and control at least some aspects of the plaintext or shared client-server state, and iterate repeatedly to refine their guesses. These issues simply don't apply in the same way to backing up files. I sure there are still theoretical issues that would need to be worked through in deciding how you'd do something like this, issues which could be better explained by any of the many crypto types who hang out here. But don't cargo cult your treatment of crypto.