Simtel MSDOS 1992 June

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/ Simtel MSDOS 1992 June / SIMTEL_0692.cdr / msdos / sysutl / passwrd9.arc / PASSWORD.ASM < prev next >

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Assembly Source File | 1989-03-15 | 17.0 KB | 575 lines

Title pw9.asm ;Originally titled PW.8 ;Rev by John R. Petrocelli 02/25/85 ;Rev by John R. Petrocelli 04/30/85 ;Rev by Durrell Drummond 10/10/86 ;Re-written by Bob Montgomery 01/10/87 ;Re-written by John Jaeger 03/12/89 ;Major changes include ready for assembly by MASM. ;Use without the ANSI.SYS driver for reasonable CRT ;displays. ;Corrected source code. The original dated 01/10/87 ;worked as stated when using the supplied object code, ;However when I added all the necessary items to compile ;with MASM, things didn't work so well. That may be due ;to the fact I am not acquainted with A86! ;Coding of the ASCII Password string so that if ;viewed by such things as XTREE, nothing jumps out ;and indicates a readable password. ;Coding of the "Prompt Strings" for the same reason ;as noted above. There is no evidence that this file ;is the one to cause the Password Check to appear on the ;screen. code segment public 'CODE' assume cs:code,ds:code,es:code driver proc near org 0 ;Required for Device Driver ;======== Driver Device Header Area ======== header: dd -1 ;One device in this file dw 8000h ;Defines character device dw strategy ;Pointer to install routine dw interrupt ;pointer to proc that handles ;the services db 'PWXYZQPR' ;8 byte string that names the ;device. Do not attempt to ;type from the Keyboard or ;anything could happen!!!! ;============================================================================ ;======== Storage for header offset and segment ======== rhoffset dw 0 rhseg dw 0 ;============================================================================ ;============================================================================ ;Area below is for some variables used by the program that installs ;PASSWORD.SYS. DO NOT change the relationship of the variable "area_length" ;to the DEVICE HEADER, or the location of the PASSWORD area! You may add ;or delete to the Screen Message area, but do not move or remove the ;"tries_left" variable in relation to the message area. ;============================================================================ area_length dw tries_left-$ password db 0 password_len equ $-password padd db 16-password_len dup(20h) ;============================================================================ ;======== Screen message character area (Encrypted) ======== msg_1 db 'Enter Password:',15 dup(20h) ;Enter Password msg_1_len dw $-msg_1 msg_2 db '****** Password Accepted *****';Password Accepted msg_2_len dw $-msg_2 msg_3 db '** Wrong Password Try Again **';Wrong Password msg_3_len dw $-msg_3 msg_4 db '******** ACCESS DENIED *******';Access Denied msg_4_len dw $-msg_4 msg_5 db 201,32 dup(205),187 ;Screen Box msg_6 db 186,32 dup(20h),186 ;Screen Box msg_7 db 200,32 dup(205),188 ;Screen Box ;============================================================================ ;Miscellaneous Variable Storage ;============================================================================ Tries_left db 0 wordlen db 0 wordbuff db 15 dup(0) tries db 3 breakoff dw 0 breakseg dw 0 video_location dw 0 cursor_location dw 0 ;============================================================================ dummyret: iret ;Pointer to Ctrl-Break vector ;inserted by this program to ;disable the Ctrl-Break ;============================================================================ ;======== main portion of program to get the user password ======== ask_password: push cs pop ds ;Set ds=cs mov ax,351bh ;Get break vector (Int 1Bh) int 21h ;from DOS mov breakoff,bx ;Save it for later mov breakseg,es push cs pop es ;Set es=cs mov dx,offset dummyret ;Set Break vector to dummyret mov ax,251bh int 21h ;via DOS check_video: ;See where video RAM is mov ah,0fh ;via video ROM int 10h cmp al,07h ;See if Mono card installed jz set_mono ;Jump to monochrome routine mov video_location,0b800h ;If not mono then Color RAM jmp video_done ;Exit routine set_mono: mov video_location,0b000h ;Set location to Mono RAM video_done: call clear_screen ;Self explanatory call box ;Routine to build entry ;box on screen xor cx,cx ;Set cx=0 mov cl,tries ;Store the number of tries mov tries_left,cl ;for later ;======== Prompt the user for the correct password ======== set_prompt: cmp cl,0 ;See if tries has expired jz go_lock_out ;Jump to routine to lock ;system if tried 3 times ;with wrong password! mov tries_left,cl ;Store the tries left mov bx,offset msg_1 ;Point to input prompt mov cx,msg_1_len ;Prep for display mov ah,0fh ;Set ah with the attribute ;that write_crt uses ;You may change this for ;different colors or intensity mov dx,0c19h ;Load dx for start location call write_crt ;to print on CRT and write it mov dx,0b27h ;Set CRT location for input ;field start xor bx,bx ;Set bx to 0 (Page 0) call position_cursor ;Set cursor to start of input ;line on CRT mov si,offset wordlen ;Point to number of char. in mov byte ptr [si],0 ;entry and initialize to 0 mov di,offset wordbuff ;Point to number of char. in ;stored password ;======== Character input routine ======== in_char: ;Lets go get some input mov ah,07h ;Use none echoing input int 21h ;from DOS cmp al,08h ;See if backspace? jz back_space ;Jump to routine to del Char. cmp al,0dh ;See if input is done? jz check_password ;Check it out cmp byte ptr [si],15 ;See if password length has jz bell ;been exceeded and ring bell mov [di],al ;Store char in wordbuff and inc di ;increment pointer mov al,0h ;Store special char for the call write_cursor ;display of an '*' on the CRT jmp in_char ;Loop for the next Character ;======== Intermediate launching point to lock the machine ======== go_lock_out: call lock_out ;Go lock up the machine ;======== Routine to back space and erase on the crt ======== back_space: cmp byte ptr [si],0 ;See if there are no char to jz bell ;erase and sound bell if none dec byte ptr [si] ;Set char count to one less dec di ;Move pointer back one in ;wordbuff mov al,0ffh ;Set erase code for erasing call write_cursor ;'*' at cursor position jmp in_char ;Loop back for next char ;======== Ring the bell routine ======== Bell: mov al,07h ;Ring the bell with DOS mov ah,0eh int 10h jmp in_char ;Back to input ;============================================================================ ;End of input routines, now lets go check what was entered! ;============================================================================ Check_password: mov di,offset password ;Point to length of our pre- cmpsb ;set word and see if the jne next_try ;length is the same and spare ;the trouble if it is not xor cx,cx ;cx=0 mov cl,wordlen ;Total char. entered into cl call convert_up ;Convert char. to upper case repe cmpsb ;compare pointers si & di cmp cl,0 ;See if all matched je ok ;Jump to exit if they were ;Fall through if not ;======== Routine to display wrong word and reset for another word ======== next_try: call off_screen ;Move curser out of the box mov dx,0c19h ;Cursor location for message mov bx,offset msg_3 ;Wrong Password message mov cx,msg_3_len ;Message length mov ah,8fh ;Blinking attribute call write_crt ;Display message mov ax,0e07h ;Ring bell int 10h mov ah,07h ;Ask for character input to int 21h ;hold screen. Any char allows ;continuation of the program mov cl,tries_left ;Set up to reduce the number dec cl ;of tries left and go back jmp set_prompt ;for another turn ;======== This is where we prepare to exit this program ======== ok: call off_screen ;Move cursor out of the box mov dx,0c19h ;Location of message mov bx,offset msg_2 ;Point to Password Accepted mov cx,msg_2_len ;Length of message mov ah,8fh ;Set attribute call write_crt ;Display successful message mov ds,breakseg ;Restore original Ctrl Break mov dx,breakoff ;vectors through DOS mov ax,251bh int 21h ret ;And return ;============================================================================ ;This subroutine converts all characters to upper case ;============================================================================ convert_up: push ax ;Save all registers push cx push ds push es push si push di push ds ;es=ds pop es mov di,si ;make di & si point to the ;same location check_char: lodsb ;Get char at si and inc si cmp al,'a' ; < a ? jl store_byte ; It's ok - store it cmp al,'z' ; > z ? jg store_byte ; It's ok - store it sub al,20h ; Make it caps Store_byte: stosb ;Store the byte at di loop Check_char ;Do all until cx=0 pop di ;Restore all registers pop si pop es pop ds pop cx pop ax ret ;And return ;============================================================================ driver endp ;============================================================================ ;This routine locks up the machine completely. If the program gets this far ;you will need to press the reset button ( If you have one ) or ;turn the power off!! ;============================================================================ lock_out proc near cli ;Disable any interrupts mov dx,0c19h ;Location on CRT for message mov bx,offset msg_4 ;Sad message !!! mov cx,msg_4_len ;Message length mov ah,8fh ;Blinking Attribute call write_crt ;Print Sad message call off_screen ;Get cursor out of box ; and locked: jmp locked ; die ! lock_out endp ;============================================================================ ;The following routines are the direct CRT display code ;============================================================================ write_crt proc near push es ;Save original es push dx ;Save location to write push ax ;Save the attribute push cx ;Save the character count push dx ;Save for the moment mov cx,02h ;Set the multiplier mov ax,video_location ;Get the address of video RAM mov es,ax ;Set the es register to RAM mov si,bx ;Point si to the message xor ax,ax ;Zero the ax mov al,dl ;Move to al the column sub al,1 ;Adjust the al imul cx ;Times to for actual column pop dx ;Get the original location mov dl,al ;Store column in dl mov al,dh ;Move into ax the row push dx ;Save for the moment sub ax,1 ;Adjust the ax mov cx,160 ;80 times 2 for actual offset imul cx pop dx ;Get dx back and dh,00h ;Zero the dh add ax,dx ;Add the column offset to the mov di,ax ;row and move di to the actual ;memory position pop cx ;Restore character count pop ax ;Restore the attribute write_crt_1: lodsb ;Load a byte of message stosw ;Store byte & attribute to RAM loop write_crt_1 ;Loop until cx=0 pop dx ;Restore original dx pop es ;restore original es ret ;And return write_crt endp write_cursor proc near mov bx,0fh ;Load attribute in bl mov cx,1 ;Load # of characters cmp al,0ffh ;See if back space jz erase_char ;If so then erase prev char mov al,'*' ;Set to display an * on CRT mov ah,09h ;Call DOS to display '*' int 10h mov dx,cursor_location ;Where in the input string inc dl ;the cursor resides and inc inc byte ptr [si] ;Increase character count xor bx,bx ;Zero the bx jmp position_cursor ;Move cursor to the next pos erase_char: mov dx,cursor_location ;Get the last position of the dec dl ;cursor and back it up call position_cursor mov ah,09h ;Set up to output a space mov al,' ' ;character over the last * int 10h ;Have DOS do it ret ;And return off_screen: xor bx,bx ;Zero bx (page 0) and set xor dx,dx ;position to upper left corner position_cursor: mov cursor_location,dx ;Store the position for later mov ah,02h ;Have DOS reset the cursor int 10h ;where we want it ret ;And return clear_screen: mov ax,0600h ;Use DOS scroll to clear CRT mov bh,07 ;Set attribute xor cx,cx ;Upper left corner 0,0 mov dx,184fh ;Lower right 24,79 int 10h ret ;And return write_cursor endp ;============================================================================ ;This routine draws a box for an entry window ;============================================================================ box proc near mov ah,04h ;Set attribute for box mov bx,offset msg_5 ;Point to Upper portion mov cx,34 ;Horizontal Length mov dx,0b17h ;Start at line 11, col 23 call write_crt ;Draw it mov bx,offset msg_6 ;Middle portion mov cx,34 ;Length mov dx,0c17h ;Start next at 12 and 23 call write_crt ;Draw it mov bx,offset msg_7 ;Bottom portion mov cx,34 ;length mov dx,0d17h ;Start next at 13 and 23 call write_crt ;Draw it ret ;And return box endp ;============================================================================ ;The following procedure is where "Lock.Com" makes its entry ;It is far procedure ending with a Interrupt Return as Lock.Com ;gets here using an int 66. ;============================================================================ lock proc far push ds ;Save Everything push es push ax push bx push cx push dx push si push di call ask_password ;Ask user for password pop di ;Restore Everything pop si pop dx pop cx pop bx pop ax pop es pop ds iret ;And return from interrupt ;============================================================================ ;This is the routine called by DOS to process the command in the request ;header. Preserve the environment and restore when done ;============================================================================ interrupt: push ds push es push ax push bx push cx push dx push si push di push cs pop ds ;Set ds=cs mov bx,rhoffset ;Get request header and mov es,rhseg ;segment loaded cmp es:byte ptr [bx+2],0 ;Command 0? (Initialize) je init ;Yes jump & initialize exit: or es:word ptr [bx+3],100h ;No Set status done pop di ;Restore environment pop si pop dx pop cx pop bx pop ax pop es pop ds ret ;============================================================================ ;The following code is the initialize code run once when DOS originally ;loads this device driver. A code is passed back to DOS showing the ;beginning location of this code. Once initialized, this code is ;discarded. ;============================================================================ init: mov dx,offset lock ;Point to entry of int 66 mov ax,2566h ;and save it through DOS int 21h push es ;Save es & bx received push bx ;from DOS ;============================================================================ ;This is the area to restore the display and password area to their ;original ASCII numbers. ;============================================================================ xor cx,cx ;Zero the counter mov cx,area_length ;Get the char count to decode mov al,40h ;Set the al to the decode # mov bx,offset password ;Point to the start position in_loop: ; add byte ptr [bx],al ;Start decoding inc bx ;Increment pointer loop in_loop ;Do until done ;============================================================================ xor cx,cx ;Prep for conversion to mov si,offset password ;Uppercase. Point to length lodsb ;of password and move to al mov cl,al ;Move char count to cl call convert_up ;Convert to upper case call ask_password ;Ask user for Password pop bx ;Restore bx & es pop es mov es:[bx+14],offset init ;Save pointer to init as mov es:[bx+16],cs ;start of free memory jmp exit ;And return to DOS lock endp ;============================================================================ ;The following Strategy procedure stores the location of the request ;header (passed by DOS in the es:bx) here. The interrupt procedure ;gets it to find the request from DOS. ;Request header format: ; Offset Content ; 0 Byte-length (of request header) ; 1 Byte-unit code (If more than one device controlled) ; 2 Byte-command (0 thru 0ch; 0=Initialize) ; 3,4 Word-Status (Bit 8=done, bit 15=error, bits 0-3=error code) ; 5-D 8 Bytes - Reserved for DOS ; E- Data-Ending address if code=0, otherwise data to transfer strategy proc far mov cs:rhoffset,bx ;Save Request header offset mov cs:rhseg,es ;Save request header segment ret ;And do a far return strategy endp code ends end