Hey,
i have seen multiple users with the same / similar errors in the past:
- Decrypt and share errors
- Occ encryption:decrypt-all, error multikeydecrypt with share key failed:error:04065072:rsa routines:rsa_ossl_private_decrypt:padding check failed
Unfortunately no one from the ownCloud community could help them so i think there is less knowledge about the encryption in ownCloud in this forum :-/
If no one could help in this forums in the future i think you could setup ownCloud new and without encryption enabled and then backup the files back to the new ownCloud installation.