Adding and Retrieving Certificate Properties

Several functions add extended properties to certificates. The original data in a certificate context is read-only and cannot be changed; however, CryptoAPI certificates also have dynamic extended properties that can be added and changed. These properties include data that:

• Pertain to the private key to be used with the certificate.
• Indicate the type of hashes to be performed on the certificate.
• Provide user-defined information associated with the certificate.

Values for these properties are attached to and move with the certificate. There are currently five predefined properties identified with property IDs:

• CERT_KEY_PROV_HANDLE_PROP_ID, CERT_KEY_PROV_INFO_PROP_ID, and CERT_KEY_CONTEXT_PROP_ID

  These properties tie a certificate to a particular CSP (Certificate Service Provider) and, within that CSP, to a particular private key.

• CERT_SHA1_HASH_PROP_ID and CERT_MD5_HASH_PROP_ID

  These properties indicate the hashing algorithm to be used when a hashing operation is performed.

CertSetCertificateContextProperty sets properties on a certificate; CertSetCRLContextProperty sets CRL properties; and CertSetCTLContextProperty sets CTL properties.

Three functions retrieve certificate properties. CertGetCertificateContextProperty retrieves certificate properties; CertGetCRLContextProperty retrieves CRL properties; and CertGetCTLContextProperty retrieves CTL properties.