[UweSchmidt]

Having to archive environments and toolchains along with backups is unpleasant.

What is the plan: when decryption fails (and before you identified that it's a versioning issue with openssl, in your case) you'd reinstall an old linux to a random computer and work from there? How many config files and settings are even involved in your backup process and how can you be sure you haven't missed anything?

I hope there are dependency-free solutions for this - a winzip-encrypted .zip file that asks for a password should work everywhere even in the future?