User Configuration > Administrative Templates > Microsoft Word 2016 > Word Options > Security > Cryptography
User
HKCU\software\policies\microsoft\office\16.0\word\security\crypto
This policy setting allows you to configure the CNG cipher algorithm that is used. If you enable this policy setting, then the cipher provided will be used if it is a supported algorithm. If you disable or do not configure this policy setting, AES will be used.