-- secret decoder with random
-- written by dw817

-- simple wait for (o) key
function key()
  repeat
    flip()
  until btnp(4)
end

-- character set to use
char=" .abcdefghijklmnopqrstuvwxyz"

-- secret text, change to
-- your liking
t="the key is under the tree."

-- store the encrypted lookup
-- table here.
decod={}

cls()

-- force all random numbers to
-- follow this seed.
srand(1)

-- get length of string char.
-- we ask for it twice in the
-- code so this is convenient.
l=#char

-- starting position for lookup
-- table.
p=0

-- go through each character of
-- the secret string.
for i=1,#t do

-- pull out a single character.
  c=sub(t,i,i)

-- reset iterations needed to
-- find a match.
  n=0

  repeat

-- retrieve a random number to
-- use in finding a matching
-- character with our secret
-- string.
    r=flr(rnd()*l)+1

-- count the number of times it
-- takes.
    n+=1

-- keep looping until we get a
-- match.
  until c==sub(char,r,r)

-- match ? output the results.
  print("char="..c.." index="..i.." iterations="..n)

-- simple delay.
  flip()

-- record the time it took in
-- our lookup array.
  decod[p]=n

-- reset time.
  n=0

-- increase index for lookup
-- table.
  p+=1

-- do every single character
-- from secret string.
end

-- wait for (o) key.
key()

cls()
?"ready to decode:"

-- reseed our random number.
-- important !
srand(1)

-- reset position in lookup
-- table.
p=0

repeat

-- loop for length of lookup
-- table in elements.
  for i=1,decod[p] do

-- get a random number the
-- length of the chars used.  
    r=flr(rnd()*l)+1

-- keep looping the same number
-- of times it took to find
-- each character matching
-- initially.
  end

-- print out each newly
-- randomly generated
-- character.
  print(sub(char,r,r),p*4,64)

-- bit of a pause.
  flip()

-- increase position in lookup
-- table.
  p+=1

-- keep looping until we have
-- covered every character.
until p==#t

-- neat, print at bottom.
print("",0,120)

-- loop forever
repeat
  key()
until forever