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.Dd August 27, 2005
.Dt KRB5_MK_REQ 3
.Os HEIMDAL
.Sh NAME
.Nm krb5_mk_req ,
.Nm krb5_mk_req_exact ,
.Nm krb5_mk_req_extended ,
.Nm krb5_rd_req ,
.Nm krb5_rd_req_with_keyblock ,
.Nm krb5_mk_rep ,
.Nm krb5_mk_rep_exact ,
.Nm krb5_mk_rep_extended ,
.Nm krb5_rd_rep ,
.Nm krb5_build_ap_req ,
.Nm krb5_verify_ap_req
.Nd create and read application authentication request
.Sh LIBRARY
Kerberos 5 Library (libkrb5, -lkrb5)
.Sh SYNOPSIS
.In krb5.h
.Ft krb5_error_code
.Fo krb5_mk_req
.Fa "krb5_context context"
.Fa "krb5_auth_context *auth_context"
.Fa "const krb5_flags ap_req_options"
.Fa "const char *service"
.Fa "const char *hostname"
.Fa "krb5_data *in_data"
.Fa "krb5_ccache ccache"
.Fa "krb5_data *outbuf"
.Fc
.Ft krb5_error_code
.Fo krb5_mk_req_extended
.Fa "krb5_context context"
.Fa "krb5_auth_context *auth_context"
.Fa "const krb5_flags ap_req_options"
.Fa "krb5_data *in_data"
.Fa "krb5_creds *in_creds"
.Fa "krb5_data *outbuf"
.Fc
.Ft krb5_error_code
.Fo krb5_rd_req
.Fa "krb5_context context"
.Fa "krb5_auth_context *auth_context"
.Fa "const krb5_data *inbuf"
.Fa "krb5_const_principal server"
.Fa "krb5_keytab keytab"
.Fa "krb5_flags *ap_req_options"
.Fa "krb5_ticket **ticket"
.Fc
.Ft krb5_error_code
.Fo krb5_build_ap_req
.Fa "krb5_context context"
.Fa "krb5_enctype enctype"
.Fa "krb5_creds *cred"
.Fa "krb5_flags ap_options"
.Fa "krb5_data authenticator"
.Fa "krb5_data *retdata"
.Fc
.Ft krb5_error_code
.Fo krb5_verify_ap_req
.Fa "krb5_context context"
.Fa "krb5_auth_context *auth_context"
.Fa "krb5_ap_req *ap_req"
.Fa "krb5_const_principal server"
.Fa "krb5_keyblock *keyblock"
.Fa "krb5_flags flags"
.Fa "krb5_flags *ap_req_options"
.Fa "krb5_ticket **ticket"
.Fc
.Sh DESCRIPTION
The functions documented in this manual page document the functions
that facilitates the exchange between a Kerberos client and server.
They are the core functions used in the authentication exchange
between the client and the server.
.Pp
The
.Nm krb5_mk_req
and
.Nm krb5_mk_req_extended
creates the Kerberos message
.Dv KRB_AP_REQ
that is sent from the client to the server as the first packet in a client/server exchange.  The result that should be sent to server is stored in
.Fa outbuf .
.Pp
.Fa auth_context
should be allocated with
.Fn krb5_auth_con_init
or
.Dv NULL
passed in, in that case, it will be allocated and freed internally.
.Pp
The input data
.Fa in_data
will have a checksum calculated over it and checksum will be
transported in the message to the server.
.Pp
.Fa ap_req_options
can be set to one or more of the following flags:
.Pp
.Bl -tag -width indent
.It Dv AP_OPTS_USE_SESSION_KEY
Use the session key when creating the request, used for user to user
authentication.
.It Dv AP_OPTS_MUTUAL_REQUIRED
Mark the request as mutual authenticate required so that the receiver
returns a mutual authentication packet.
.El
.Pp
The
.Nm krb5_rd_req
read the AP_REQ in
.Fa inbuf
and verify and extract the content.
If
.Fa server
is specified, that server will be fetched from the
.Fa keytab
and used unconditionally.
If
.Fa server
is
.Dv NULL ,
the
.Fa keytab
will be search for a matching principal.
.Pp
The
.Fa keytab
argument specifies what keytab to search for receiving principals.
The arguments
.Fa ap_req_options
and
.Fa ticket
returns the content.
.Pp
When the AS-REQ is a user to user request, neither of
.Fa keytab
or
.Fa principal
are used, instead
.Fn krb5_rd_req
expects the session key to be set in
.Fa auth_context .
.Pp
The
.Nm krb5_verify_ap_req
and
.Nm krb5_build_ap_req
both constructs and verify the AP_REQ message, should not be used by
external code.
.Sh SEE ALSO
.Xr krb5 3 ,
.Xr krb5.conf 5