I don't know. Just do what this library does: encrypt rows with AES-GCM. Use random keys, push the keys to clients in cookies or to store in local storage. The server "sees" the key when incoming requests arrive, but doesn't store them.

Thanks.

Hm I still would prefer plain text not leaving the device. There have been historical examples of plain text passwords ending up in logs (Twitter) so I would prefer encrypted on my device so there's no chance of interception (mistaken or purposeful) on the server.

Plus this would result in a loss of features - keys would then live only on a device for as long as the cookies/storage existed. New browser/device/clean storage the keys are lost and the ciphertext unable to be decrypted.