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 cipher chaining mode used. If you enable this policy setting, the cipher chaining mode specified will be applied. If you disable or do not configure this policy setting, Cipher Block Chaining (CBC) will be the default CNG cipher chaining mode used.