[Shebang]

Encode:

Code:

print'#'.join(oct(ord(x)^17)[::-1]for x in raw_input())

Retrieves the ASCII value of each character, figures out that value XOR 17, converts it to it's octal (base 8) value and reverses it. Since XOR is associative, this will be easy to reverse.

Decode:

Code:

print''.join(chr(int(x[::-1],8)^17)for x in raw_input().split("#"))

Not very complex, but my score is guaranteed to be <= 1.