ÐASSWORD 64
BY ÊOHN ËISSELL

ÐASSWORD 64 ALLOWS YOU TO PROTECT ANY ÂASIC FILE THAT YOU HAVE LABORED LONG AND HARD TO COMPLETE. ÏNCE THE ÂASIC PROGRAM IS MODIFIED USING ÐASSWORD 64, IT CAN BE USED WITHOUT THE NEED FOR SPECIAL PROGRAMS OR UTILITIES.

ÔO USE ÐASSWORD 64, YOU MUST OBSERVE TWO RESTRICTIONS. ÆIRST, THE FILE THAT YOU WISH TO PROTECT CAN NOT START WITH A LINE NUMBER OF ZERO (0). ÆOR YOUR CONVENIENCE, A RENUMBERING UTILITY IS INCLUDED. ÓEE BELOW FOR "ÒENUMBER 64" INFORMATION. ÓECOND, COMPUTER MEMORY BEGINNING AT 49152 ($Ã000) MUST BE FREE OF RESIDENT PROGRAMS, SUCH AS ÒÕÎ'S ÃHECKSUM. ÉF IN DOUBT, LOAD ÐASSWORD 64 FROM A COLD START.

ÔO INSTALL ÐASSWORD 64, JUST LOAD AND RUN IT USING ÍENU 64. ÔHE OPERATING CODE IS MOVED TO ADDRESS 49152 (HEX $Ã000) AND THE LOADER PORTION IS DELETED. ÆOUR PROMPTS THEN APPEAR. ÊUST TYPE IN THE NAME OF THE PROGRAM THAT YOU WANT TO PROTECT. ÔHE FILE MUST BE PURE ÂASIC 2.0, WITH NO MACHINE LANGUAGE ROUTINES.

ÐASSWORD IS NOT DESIGNED TO HANDLE ÂASIC LOOK-ALIKES OR BINARY FILES. ÁLSO, IF YOU ARE USING A DISK DRIVE OTHER THAN 8, LIST THE DEVICE NUMBER AFTER THE FILENAME. ÆOR EXAMPLE, ENTER "ÍÙÆÉÌÅ,9", AT THE FIRST PROMPT. ÏNCE A DEVICE NUMBER IS ENTERED IT BECOMES THE DEFAULT DEVICE FOR THE CURRENT SESSION.

ÔHE SECOND PROMPT ASKS FOR A PASSWORD. ÓPECIFY A PASSWORD OF FROM ONE TO TEN ÁÓÃÉÉ CHARACTERS. ÕSE LOWER OR UPPER CASE LETTERS, NUMERALS OR PUNCTUATION. ×HEN YOU PRESS ÒETURN THREE THINGS HAPPEN.  ÆIRST, AN ADDITIONAL ÂASIC LINE NUMBER 0 IS INSERTED.  ÔHEN YOUR PROGRAM IS ENCRYPTED BASED ON YOUR PASSWORD. ÔHIRD, A MACHINE LANGUAGE DECODE/RE-ENCODE ROUTINE IS APPENDED TO THE END OF THE PROGRAM. ÁLTHOUGH A MACHINE LANGUAGE MONITOR EASILY SHOWS HOW THE DECODE ROUTINE WORKS, WITHOUT THE PASSWORD, YOUR ÂASIC PROGRAM IS ALMOST IMPOSSIBLE TO DECIPHER.

ÔHE THIRD PROMPT ASKS FOR A FILENAME TO SAVE THE ENCRYPTED PROGRAM UNDER. ÁS WITH THE ORIGINAL LOAD PROMPT, YOU CHANGE THE DEFAULT DEVICE NUMBER BY LISTING IT AFTER THE FILENAME.

ÌOAD AND RUN AN ENCYPTED PROGRAM EXACTLY THE SAME AS ANY OTHER ÂASIC PROGRAM. ×HEN THE PROGRAM IS RUN THE USER IS FIRST PROMPTED FOR THE PASSWORD. ÔHE CORRECT PASSWORD ALLOWS THE PROGRAM TO RUN AFTER A SHORT DECODING DELAY. ×HEN THE PROGRAM STOPS RUNNING, REGARDLESS OF THE REASON, THE PROGRAM'S CONTENTS ARE IMMEDIATELY RE-ENCRYPTED. ÁN INCORRECT PASSWORD GENERATES AN "ACCESS DENIED" ERROR AND THE USER IS RETURNED TO ÂASIC.

ÎO OTHER PROGRAMS OR UTILITIES ARE REQUIRED. ÔHE ENCRYPTED PROGRAM HAS ALL THE INFORMATION IT NEEDS TO RUN UNDER PASSWORD PROTECTION. ÉF YOU LIST THE FILE, ALL APPEARS IS LINE 0 WHICH IS A ÓÙÓ CALL TO THE DECODE ROUTINE. ÄELETING STATEMENT #0 IN EFFECT DELETES THE ENTIRE PROGRAM. ÙOU CAN NOT EDIT, LIST OR PRINT A PASSWORD PROTECTED PROGRAM. ÙOU CAN MAKE COPIES EITHER BY LOADING AND RESAVING OR WITH A FILE COPIER. ËEEP COPIES OF THE UNENCRYPTED VERSION FOR LATER ADDITIONS OR REVISIONS.

ÔHE LAST PROMPT ASKS IF YOU WISH TO PROTECT ANOTHER FILE. ÁNSWER YES OR NO. Á DISK ERROR OR A NULL RESPONSE TO EITHER OF THE FIRST THREE PROMPTS CAUSES THE PROGRAM TO EXIT TO ÂASIC. ÊUST ENTER ÓÙÓ 49152 TO RESTART.