anchor.diff:  ;; this should return a "credential handle" for input into initialize-security-context or accept-security-context
   ;; but somehow the "credentials" need to be input into this function.
   (defgeneric acquire-credentials (mech-type principal &key)
  -  (:documentation "Acquire credentials for the principal named. Returns CREDENTIALS, for input into INITIALIZE-SECURITY-CONTEXT. c.f. GSS_Acquire_cred.
  +  (:documentation "Acquire credentials for the principal named. Returns CREDENTIALS, for input into INITIALIZE-SECURITY-CONTEXT and ACCEPT-SECURITY-CONTEXT. 
  +c.f. GSS_Acquire_cred.
   
  -MECH-TYPE ::= symbol naming the authentication mechamism
  -PRINCIPAL ::= the security principal you are requesting credentials for. NIL assumes default.
  +MECH-TYPE ::= symbol naming the authentication mechamism.
  +
  +PRINCIPAL ::= the name of the principal you are requesting credentials for. NIL assumes default.
  +
  +Returns an opaque credential object to be used in subsequent calls.
   "))
   
   ;; NOTE: this function MUST return an InitialContextToken structure, i.e. an ASN.1 DER encoded structure. 
  
positive.code: ;; has been returned from a prior call to INITIALIZE-SECURITY-CONTEXT. In the later case, this implies
  ;; validating a reply from the application server (to verify its identity). The received token should also 
  ;; be passed in via a keyword parameter.
  (defgeneric initialize-security-context (credentials &key)
    (:documentation "Returns a security context to be sent to the application server. c.f. GSS_Init_sec_context"))
  
  (defgeneric accept-security-context (credentials buffer &key)
    (:documentation "CREDENTIALS are credentials for the server principal. CONTEXT is the packed 
  buffer sent from the client. It should be as returned from INITIALIZE-SECURITY-CONTEXT.
  
  c.f. GSS_Accept_sec_context
  "))
  
  ;; Get_MIC()
  
negative.code: 
  ;; something like GSS_Display_Name
  (defgeneric context-principal-name (context &key)
    (:documentation "Returns a string which represents the name of the principal to which is authenticated by this context. 
  This function should be used by servers wishing to get some information on the identity of the client.
  "))
  