User Configuration > Administrative Templates > Microsoft Office 2016 > Security Settings > Digital Signatures
User
HKCU\software\policies\microsoft\office\16.0\common\signatures
This policy setting allows you to configure the hashing algorithm Office 2016 applications use to confirm digital signatures. If you enable this policy setting, you can specify any of the following SHA standard functions: - SHA1 - SHA256 - SHA384 - SHA512 If you disable or do not configure this policy setting, the default value of SHA1 is used.