Configure invalid RSA public key size

Supported on: At least Windows Server 2008 R2 or Windows 7

Registry

HKCU software\policies\microsoft\office\16.0\common\signatures

Options

invalidrsabits enum
  • 0
  • 512
  • 768
  • 1024
  • 1536
  • 2048

Description

This policy setting allows you to configure whether Office displays a digital signature as invalid because of the number of RSA public key bits used in the digital signature. If you enable this policy setting, you can specify the number of bits that Office treats as invalid in a digital signature. For example: 512, 768, etc. If you don’t configure this policy setting, Office won’t treat any digital signatures as invalid because of the number of bits in the public key. Enabling this policy causes the minimum RSA public key size to be the next largest option.