Database encryption
Starting with V11.0.1, Domino supports encrypting databases with AES 128-bit encryption.
If the Domino databases are already encrypted with any other strengths like Simple, Medium, or Strong, then it will not support direct encryption to AES 128 encryption strength.
To encrypt the database with AES 128 encryption strength, first the previous encryption should be removed by selecting Do not locally encrypt this database option. Later, the database can be re-encrypted by selecting 128-bit AES from the Strong Encryption dropdown of the Locally encrypt this database using option.