See Also: SignerInfo Members
The signatures represented by the System.Security.Cryptography.Pkcs.SignerInfo class can be either over message content or a signature. The latter kind of signature is referred to as a countersignature.
This implementation of CMS/PKCS #7 supports only one level of countersignature. That is, a signature can be signed, which forms a countersignature, but that countersignature cannot be signed again.
This class does not have a public constructor; therefore, it cannot be publicly instantiated. It is a read-only class accessible from the SignedCms.SignerInfos property.