The System.Security.Cryptography.Pkcs.Pkcs9MessageDigest class defines the message digest of a CMS/PKCS #7 message.
See Also: Pkcs9MessageDigest Members
A System.Security.Cryptography.Pkcs.Pkcs9MessageDigest object will be automatically generated and placed in the SignerInfo.SignedAttributes property whenever the CmsSigner.SignedAttributes property for the corresponding signer is not empty.