The gss_get_mic() function generates a cryptographic MIC for the supplied message, and places the MIC in a token for transfer to the peer application. The qop_req parameter allows a choice between several cryptographic algorithms, if supported by the chosen mechanism.

Since some application-level protocols may wish to use tokens emitted by gss_wrap(3GSS) to provide secure framing, the GSS-API allows MICs to be derived from zero-length messages.

The parameter descriptions for gss_get_mic() follow:

minor_status

The status code returned by the underlying mechanism.

context_handle

Identifies the context on which the message will be sent.

qop_req

Specifies the requested quality of protection. Callers are encouraged, on portability grounds, to accept the default quality of protection offered by the chosen mechanism, which may be requested by specifying GSS_C_QOP_DEFAULT for this parameter. If an unsupported protection strength is requested, gss_get_mic() will return a major_status of GSS_S_BAD_QOP.

message_buffer

The message to be protected.

msg_token

The buffer to receive the token. Storage associated with this message must be freed by the application after use with a call to gss_release_buffer(3GSS).

gss_get_mic() may return the following status codes:

GSS_S_COMPLETE

Successful completion.

GSS_S_CONTEXT_EXPIRED

The context has already expired.

GSS_S_NO_CONTEXT

The context_handle parameter did not identify a valid context.

GSS_S_BAD_QOP

The specified QOP is not supported by the mechanism.

GSS_S_FAILURE

The underlying mechanism detected an error for which no specific GSS status code is defined. The mechanism-specific status code reported by means of the minor_status parameter details the error condition.

See attributes(5) for descriptions of the following attributes:

gss_release_buffer(3GSS), gss_wrap(3GSS), attributes(5)

GSS-API Programming Guide