extern struct key_type key_type_user;
extern int user_instantiate(struct key *key, const void *data, size_t datalen);
-extern int user_duplicate(struct key *key, const struct key *source);
extern int user_update(struct key *key, const void *data, size_t datalen);
extern int user_match(const struct key *key, const void *criterion);
+extern void user_revoke(struct key *key);
extern void user_destroy(struct key *key);
extern void user_describe(const struct key *user, struct seq_file *m);
extern long user_read(const struct key *key,