The System.Security.Cryptography.Pkcs.SubjectIdentifierType enumeration defines the type of subject identifier.
The subject is identified by the certificate issuer and serial number.
The subject is identified as taking part in an integrity check operation that uses only a hashing algorithm.
The subject is identified by the hash of the subject's public key. The hash algorithm used is determined by the signature algorithm suite in the subject's certificate.
The type of subject identifier is unknown.