Cloud storing wallet.keys encrypted files

Question

How safe is it to store the wallet.keys files in a cloud service, email, website, etc? I imagine that it should be just as secure as the passphrases used to encrypt the file. If I understood it correctly, it uses Chacha8, which I believe is very standard, state-of-the-art encryption. Is that correct?

Also, does the file itself leak any other information, like what it is, the wallet address, etc? And are there precautions if renaming it?

EDIT: Added later: If the wallet.keys file is copied while in use, could the user, by accident, end up saving an unencrypted version of it, or are those files always encrypted, and whenever the wallet uses the keys it does so decrypting a copy of wallet.keys internally and securely?

EDIT: Added later: Also, are the wallet files (without the .keys extension), that store the wallet's transaction history, also encrypted with the same passphrase?

Answer 1

Your wallet.keys file should be perfectly safe in the cloud as long as your passphrase to unlock it remains secure.

You are correct about the use of Chacha8 to protect the file.

As long as the file remains encrypted, wallet.keys will not leak any data. Renaming it should not be a problem, but to be safe I would keep a backup of the original file (prior to the name change) until you confirm the renamed file still opens properly with your passphrase.