INCLUDE irvine32.inc

     BUFMAX = 128 ; maximum buffer size


   .data

    key BYTE BUFMAX+1 DUP(0)
    keySize DWORD ?

    mes BYTE BUFMAX+1 DUP(0)
    mesSize DWORD ?


    msgWel  BYTE    "Welcome! This program encrypts and decrypts a message using any key and message!", 0DH, 0AH, 0
    msgEn   BYTE    "Please enter the Encryption Key: ", 0
    msgMe   BYTE    "Please enter the Message you want Encrypted: ", 0
    msgFin  BYTE    "The Encrypted Message is: ", 0
    msgUn   BYTE    "The Decrypted Message is: ", 0
    msgAny  BYTE    "Press any key to continue...", 0DH, 0AH, 0

.code
main PROC

call Input

call Encryption

mov EDX, offset msgFin
call WriteString

mov EDX, offset mes
call WriteString

call Encryption

mov EDX, offset msgUn
call WriteString

mov EDX, offset mes
call WriteString

call Crlf

mov EDX, offset msgAny
call WriteString
call ReadInt

exit


main ENDP


Input PROC
pushad                      ; save 32-bit registers

mov EDX, offset msgWel      ; display a prompt
call WriteString

mov EDX, offset msgEn       ; display a prompt
call WriteString

mov ECX, BUFMAX             ; maximum character count

mov EDX, offset key         ; point to the key
call ReadString             ; input the string

mov keySize, EAX            ; save the length for key



mov EDX, offset msgMe       ; display a prompt
call WriteString

mov ECX, BUFMAX             ; maximum character count

mov EDX, offset mes         ; point to the key
call ReadString             ; input the string

mov mesSize, EAX            ; save the length for message

call Crlf
popad
ret

Input ENDP



Encryption PROC
pushad
mov ECX, mesSize            ; loop counter
mov ESI, 0
mov EAX, 0                  ; index 0 in message

L1:
mov AL, key[EAX]
xor mes[ESI], AL        ; translate a byte
inc ESI
inc EAX

cmp keySize, EAX
jb  below

loop L1

below:
mov EAX, 0
loop L1


call crlf
popad
ret

Encryption ENDP


END main