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LOCK.ASM
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Assembly Source File
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1990-01-28
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6KB
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241 lines
title Password Locked System Program.
page 60,120 ; page length = 60
; page width = 120
;
; This program lock a system to protect open network connections.
;
; LOCK : Copyright (c) 1989 by John Wolchak.
; This program is released into the Public Domain.
;
; John Wolchak.
; 56 Physics Building
; University of Saskatchewan.
; Saskatoon, Saskatchewan
; Canada S7K 0W0
; Phone: (306) 966-4852
; NetNorth (BITNET): Wolchak@Sask
; Inter_Network: Wolchak@Admin.Usask.Ca
;
; To assemble:
; masm lock,,,
; link lock,,,
; exe2bin lock.exe lock.com
;
code segment
assume cs:code,ds:code
org 100h
start: jmp beginning
;
; Data Area
;
exit_code db 02h ; Help message displayed.
v_error db 13,10,"Password verification failed",13,10,"$"
u_prompt db 13,10,13,10,"Unlock Password> $"
l_prompt db 13,10,"Lock Password> $"
v_prompt db 13,10,"Verification> $"
s_pass dw 00h ; Size of password.
d_pass db 80 dup(0) ; Original Password.
v_pass db 80 dup(0) ; Verification Password.
dos_maj db 00h ; DOS major version.
dos_min db 00h ; DOS minor version.
author db "Lock by Password System Program.",13,10
db "V1.0 (c) 23-Nov-1989 by John Wolchak.",13,10
db 13,10
help db "Usage: LOCK",13,10,9,9
db 13,10
db "Example: lock ",13,10,9,9
db "Lock Password> ",13,10,9,9
db "Verification> ",13,10,9,9
db 13,10,9,9
db "Unlock Password> ",13,10
db "$"
;
; Code Area
;
Beginning:
mov si, 80h ; Offset of command line.
lodsb ; Get a byte.
cmp al, 00h ; Is there any data.
jz get_ver ; Yes. Jump.
cmp al, 0dh ; Is there any data.
jz get_ver ; Yes. Jump.
dis_help:
mov dx, offset author ; Help message.
mov ah, 09h ; Display it.
int 21h
mov exit_code, 00h ; Command, help issued.
jmp nor_term ; Exit.
get_ver:
mov ah, 30h ; Get DOS version number.
int 21h
mov dos_maj, al ; Save major version.
mov dos_min, ah ; Save minor version.
cmp ah, 01h
jnz cont
mov exit_code, 01h ; No MS-DOS version 1.x.
jmp nor_term ; Exit.
cont:
lodsb ; Get a byte.
cmp al, " " ; Is it leading blank.
jz cont ; Yes. Loop.
cmp al, 09h ; Is it leading tab.
jz cont ; Yes. Loop.
cmp al, 0dh ; Is it a carriage return.
jnz dis_help ; Yes. dis_help.
again:
; Get the lock password.
mov ax, offset d_pass ; Where we will store
mov di, ax ; the password.
mov bx, 00h ; Password size.
; Display the prompt.
mov dx, offset l_prompt ; lock password prompt.
mov ah, 09h ; Display it.
int 21h
; Direct Charater Input without echo.
l_loop: mov ah, 07h ; Read a character.
int 21h ; Get it.
; Get the password,
; and convert to upper case.
cmp al, " " ; Is it a blank.
jz l_loop ; Yes. Loop.
cmp al, 09h ; Is it a tab.
jz l_loop ; Yes. Loop.
cmp al, 0dh ; Is it the end.
jz l_got ; Yes. We got it.
cmp al, "z" ; Is
jg l_not ; it
cmp al, "a" ; lower
jb l_not ; case?
sub al, 20h ; Make it upper case.
l_not:
inc bx ; Count the characters.
stosb ; Save the byte.
cmp bx, 80h ; Too long.
jz again ; Yes. Try again.
jmp l_loop
l_got:
cmp bx, 00h ; Do we have data.
jnz l_cont ; No quit.
mov exit_code, 02h ; Program abort.
jmp nor_term
l_cont:
mov s_pass, bx ; Save the size.
mov ax, offset v_pass ; Where we will store
mov di, ax ; the password.
mov bx, 00h ; Password size.
; Display the prompt.
mov dx, offset v_prompt ; Verify password prompt.
mov ah, 09h ; Display it.
int 21h
; Direct Charater Input without echo.
v_loop: mov ah, 07h ; Read a character.
int 21h ; Get it.
; Get the password,
; and convert to upper case.
cmp al, " " ; Is it a blank.
jz v_loop ; Yes. Loop.
cmp al, 09h ; Is it a tab.
jz v_loop ; Yes. Loop.
cmp al, 0dh ; Is it the end.
jz v_got ; Yes. We got it.
cmp al, "z" ; Is
jg v_not ; it
cmp al, "a" ; lower
jb v_not ; case?
sub al, 20h ; Make it upper case.
v_not:
inc bx ; Count the characters.
stosb ; Save the byte.
cmp bx, 80h ; Too long.
jz ver_err ; Yes. Try again.
jmp v_loop
v_got:
cmp s_pass, bx ; Is it the wrong size?
jnz ver_err ; Yes try it again.
mov di, offset v_pass ; Set destination.
mov si, offset d_pass ; Set Source.
mov cx, s_pass
rep cmpsb ; Does it verify.
jz unl_pass ; Yes. Jump out.
; Display error message.
ver_err:
mov dx, offset v_error ; Error message.
mov ah, 09h ; Display it.
int 21h
jmp again
; Unlock password.
unl_pass:
mov ax, offset v_pass ; Where we will store
mov di, ax ; the password.
mov bx, 00h ; Password size.
; Display the prompt.
mov dx, offset u_prompt ; Unlock password prompt.
mov ah, 09h ; Display it.
int 21h
; Direct Charater Input without echo.
u_loop: mov ah, 07h ; Read a character.
int 21h ; Get it.
; Get the password,
; and convert to upper case.
cmp al, " " ; Is it a blank.
jz u_loop ; Yes. Loop.
cmp al, 09h ; Is it a tab.
jz u_loop ; Yes. Loop.
cmp al, 0dh ; Is it the end.
jz u_got ; Yes. We got it.
cmp al, "z" ; Is
jg u_not ; it
cmp al, "a" ; lower
jb u_not ; case?
sub al, 20h ; Make it upper case.
u_not:
inc bx ; Count the characters.
stosb ; Save the byte.
cmp bx, 80h ; Too long.
jz unl_pass ; Yes. Try again.
jmp u_loop
u_got:
cmp s_pass, bx ; Is it the wrong size?
jnz unl_pass ; Yes try it again.
mov di, offset v_pass ; Set destination.
mov si, offset d_pass ; Set Source.
mov cx, s_pass
rep cmpsb ; Does it verify.
jz next ; Yes. Jump out.
jmp unl_pass
next:
; Exit the program.
nor_term:
mov al, cs:[exit_code] ; Set termination code.
mov ah, 4ch ; Termination.
int 21h
code ends
end start