The WSIT Tutorial

SAML Holder of Key

This mechanism protects messages with a signed SAML assertion (issued by a trusted authority) carrying client public key and authorization information with integrity and confidentiality protection using mutual certificates. The Holder-of-Key (HOK) method establishes the correspondence between a SOAP message and the SAML assertions added to the SOAP message. The attesting entity includes a signature that can be verified with the key information in the confirmation method of the subject statements of the SAML assertion referenced for key info for the signature. For more information about the Holder of Key method, read the SAML Token Profile document at

Under this scenario, the service does not trust the client directly, but requires the client to send a SAML assertion issued by a particular SAML authority. The client knows the recipient’s public key, but does not share a direct trust relationship with the recipient. The recipient has a trust relationship with the authority that issues the SAML token. The request is signed with the client’s private key and encrypted with the server certificate. The response is signed using the server’s private key and encrypted using the key provided within the HOK SAML assertion.