const dictionary := "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
const numbers := "1234567890"

fcn encrypt (str, key : string) : string
    var news := ""
    var s := Str.Upper (str)
    for i : 1 .. length (s)
        if index (dictionary, s (i)) > 0 then
            news += chr (65 + (((ord (s (i)) - 65) + (ord (key (i mod length (key) + 1)) - 65)) mod 26))
        elsif index (numbers, s (i)) > 0 then
            news += chr (49 + (((ord (s (i)) - 49) + (ord (key (i mod length (key) + 1)) - 49)) mod 10))
        else
            news += s (i)
        end if
    end for
    result news
end encrypt

fcn decrypt (str, key : string) : string
    var news := ""
    var s := Str.Upper (str)
    for i : 1 .. length (s)
        if index (dictionary, s (i)) > 0 then
            news += chr (65 + (((ord (s (i)) - 65) - (ord (key (i mod length (key) + 1)) - 65)) mod 26))
        elsif index (numbers, s (i)) > 0 then
            news += chr (49 + (((ord (s (i)) - 49) - (ord (key (i mod length (key) + 1)) - 49)) mod 10))
        else
            news += s (i)
        end if
    end for
    result news
end decrypt

var input, message : string

put "Input message to encrypt: " ..
get message : *
put "Input your password: " ..
get input : *

message := encrypt (message, input)

cls

loop
    put "Your encrypted message: ", message
    put "Input the password to display the message: " ..
    get input
    put "The message with this key reads: ", decrypt (message, input)
    put "Press any key to continue..."
    loop
        exit when hasch
    end loop
    cls
end loop