Then 3 steps. 1. Use tarsnap so there's an encryption and a management layer. 2. Use a second service so there's redundancy and no SPoF. 3. Keep cryptographi

Then 3 steps. 1. Use tarsnap so there's an encryption and a management layer. 2. Use a second service so there's redundancy and no SPoF. 3. Keep cryptographic signatures (not hashes) of each backup job in something like a WORM blockchain KVS.