/*
 * There are two kinds of credentials: one in which the client
 * uses its full network name, and one in which it uses its
 * "nickname" (just an unsigned integer) given to it by the
 * server. The client must use its full name in its first
 * transaction with the server, in which the server will return
 * to the client its nickname. The client may use its nickname
 * in all further transactions with the server. There is no
 * requirement to use the nickname, but it is wise to use it for
 * performance reasons.
 */
enum authdes_namekind {
 	ADN_FULLNAME = 0,
 	ADN_NICKNAME = 1
 };

/*
 * A 64-bit block of encrypted DES data
 */
 typedef opaque des_block[8];

/*
 * Maximum length of a network user's name
 */
const MAXNETNAMELEN = 255;

/*
 * A fullname contains the network name of the client, an
 * encrypted conversation key and the window. The window
 * is actually a lifetime for the credential. If the time
 * indicated in the verifier timestamp plus the window has
 * passed, then the server should expire the request and 
 * not grant it. To insure that requests are not replayed,
 * the server should insist that timestamps be greater
 * than the previous one seen, unless it is the first transaction.
 * In the first transaction, the server checks instead that the
 * window verifier is one less than the window.
 */
struct authdes_fullname {
 	string name<MAXNETNAMELEN>; /* name of client */
 	des_block key;              /* PK encrypted conversation key */
 	unsigned int window;        /* encrypted window */
};                             /* NOTE: PK means "public key" */
/*
 * A credential is either a fullname or a nickname
 */
unionauthdes_credswitch(authdes_namekindadc_namekind){
 	case ADN_FULLNAME:
 		authdes_fullname adc_fullname;
 	case ADN_NICKNAME:
 		unsigned int adc_nickname;
};
/*
 * A timestamp encodes the time since midnight, January 1, 1970.
 */
struct timestamp {
 	unsigned int seconds;      /* seconds */
 	unsigned int useconds;     /* and microseconds */
};

/*
 * Verifier: client variety
 */
struct authdes_verf_clnt {
 	timestamp adv_timestamp;   /* encrypted timestamp */
 	unsigned int adv_winverf;  /* encrypted window verifier */
};

/*
 * Verifier: server variety
 * The server returns (encrypted) the same timestamp the client gave
 * it minus one second. It also tells the client its nickname to be
 * used in future transactions (unencrypted).
 */
struct authdes_verf_svr {
 	timestamp adv_timeverf;    /* encrypted verifier */
 	unsigned int adv_nickname; /* new nickname for clnt */
};