;
; TED v1.0
; (Text Encryption Device)
;
; Written by Data Disruptor
; (c) 1991 The RABID International Development Corp.
;

@print  macro   string
        mov     ah,09h
        mov     dx,offset string
        int     21h
endm

	dosseg
	.model small
	.stack 100h
	.data

ident   db   13,10
        db   "Text Encryption Device (TED) v1.0",13,10
        db   "Written by Data Disruptor (Aug.16.91)",13,10,13,10
        db   "(c) 1991 The RABID International Development Corp.",13,10,13,10
        db   "Please enter text now",13,10
        db   ">$"



open_er db      "Error opening file",13,10,"$"

writ_er db      "Error writing data",13,10,"$"

clos_er db      "Error closing file",13,10,"$"

saved   db      "Encrypted text saved in ENCRYPT.TXT",13,10,"$"

input   db      80 dup (?)                      ; Set input buffer

dest	db      80 dup (?)			; Set a blank field to be
						; the destination point for
						; the encrypted string
temp	db	0				; Tåmporary encrypted 
						; charachter buffer
dol	db	"$",13,10                       ; EOL so that we don't get
				                ; a whole lot of crap on
                                                ; the screen
crlf    db      13,10,"$"

counter db      0                               ; For # of keypresses

file    db      "encrypt.txt",0
filehndl dw     0                               ; Save the file handle

	.code

start:	mov	ax,@data			; Read @DS into AX
	mov	ds,ax				; Copy AX into DS

        @print  ident

        mov     si,offset input
        mov     cx,1
keyp:
        mov     ah,01h                          ; Get keypress
        int     21h
        cmp     al,13                           ; Is it a CR?
        je      exit_key                        ; Yes? Quit
        cmp     al,8
        je      dec_si
        mov     [si],al                         ; No? Store the keypress
        inc     cx
        inc     si
        jmp     keyp

dec_si: dec     si
        jmp     keyp

exit_key:
        @print  crlf
	mov	si,offset input			; Copy string into SI
	mov	di,offset dest			; Copy target into DI
encrypt:mov	al,ds:[si]			; Copy first charachter
						; in SI into AL
	mov	temp,al				; Copy AL into TEMP
	xor	byte ptr ds:[temp],1ah		; Encrypt TEMP with byte 01h
	mov	al,temp				; Copy TEMP back into AL
	mov	[di],al				; Move AL into DI
	inc	si				; Increase counter [SI]
	inc	di				; Increase counter [DI]
	loop	encrypt				; Get the next byte in the
						; string
	mov	dx,offset dest			; copy encrypted string into DX
	call	print				; INT 21h, func 09h
	jmp	quit				; Quit the program

print:	mov	ah,09h				; Procedure to output ståing
	int	21h				; in DX to the screen
	ret					; Return to where we were
						; called from

quit:   mov	dx,offset dol
	call	print
        mov     ah,3ch                          ; Create a file
        xor     cx,cx                           ; Normal attributes
        mov     dx,offset file                  ; Set the name of the file
        int     21h
        jc      open_error

        mov     word ptr [filehndl],ax          ; Save the file handle

        mov     ah,40h
        mov     bx,word ptr [filehndl]
        mov     cx,80
        mov     dx,offset input
        int     21h

        mov     ah,40h                          ; Write to file
        mov     bx,word ptr [filehndl]          ; Set file handle in BX
        mov     cx,80
        mov     dx,offset dest                  ; Set for text buffer
        int     21h

        jc      write_error

        mov     ah,3eh                          ; Close the file
        mov     bx,word ptr [filehndl]          ; ...in the file handle...
        int     21h

        jc      close_error

        @print  saved
        jmp     bye

open_error:
        @print  open_er
        jmp     error
write_error:
        @print  writ_er
        jmp     error
close_error:
        @print  clos_er
        jmp     error

error:  mov     ah,0eh
        mov     al,07                           ; Beep!
        int     10h

bye:
	mov	ax,4c00h			; Terminate program with
	int	21h				; exit code 00
end	start				        ; Gedoudahere!