>> FN SCRAMBLE$ and FN UNSCRAMBLE$ are designed to work
>> in conjunction as an elementary encryption solution.
>> 
>> FN SCRAMBLE$ relies on a key word to encrypt the input
>> word. The same key is used to unscramble the output
>> when washed back through FN UNSCRAMBLE.
>> 
>Based on your functions, here are my entries (I hope I got the thing
>right) that runs more than 10 times faster mainly because the string
>manipulation is not done in a Standard BASIC way:

Alain,

Nice code. The only things I would consider altering would be:

change
digitSum  = digitSum MOD 128
to
digitSum  = digitSum AND 127

Search and replace "keyStr[0]" with "L"
Then add
DIM L
L = keyStr[0]

I know it adds a variable, but it makes for faster, cleaner code.