BaldCrypt.py

def step_waves(waves):
  for i in xrange(len(waves)):
    if i + 1 < len(waves):
      waves[i] += waves[i+1] - 8
    
    # This is almost modulo 15, but not quite
    if waves[i] > 15:
      waves[i] -= 15
    elif waves[i] < 0:
      waves[i] += 15
  
  return waves[0]

def setup_waves(key):
  waves = [ int(key[i], 16) for i in xrange(len(key)) ]
  for _ in xrange(1024):
    step_waves(waves)
  return waves

def crypt(key, message):
  output = []
  waves = setup_waves(key)
  for m in message:
    hi = (ord(m) / 16) ^ step_waves(waves)
    lo = (ord(m) % 16) ^ step_waves(waves)
    output.append(16 * hi + lo)
  return ''.join(chr(o) for o in output)