The way you have this currently is not very practical, or up to par on coding conventions if I may point out. Arrays like that are a bit "sloppy".. Not sure about this language, but if you can you should probably just declare it as a string and index the chars individually, otherwise use the brackets { & } and have everything separated by comma.
What language is this? Right now I can only take a guess, but it would help if others knew what language you were using. This could have been VB.NET formatted in a more VB6 style... Although with the exception of these 2 lines, so i'm assuming it's some other .NET language that I haven't used yet.
Code:
input "Encrypted message:" ; encmsg$
I will say that you would only need one array for this though. (Really only one string actually.)
Cheers
~Ace