extern int auth_check_some_cond(auth_instance *, uschar *, uschar *, int);
-extern int auth_get_data(uschar **, uschar *, int);
+extern int auth_get_data(uschar **, const uschar *, int);
extern int auth_get_no64_data(uschar **, uschar *);
extern void auth_show_supported(FILE *);
extern uschar *auth_xtextencode(uschar *, int);
extern gstring *authres_spf(gstring *);
#endif
-extern uschar *b64encode(uschar *, int);
+extern uschar *b64encode(const uschar *, int);
extern int b64decode(const uschar *, uschar **);
extern int bdat_getc(unsigned);
extern uschar *bdat_getbuf(unsigned *);