I'm not really sure of that one, maybe an input exemple would help (if you have the other dev's code, you could make a data/encoded pair for us to try) but if he uses utf-8 encoding already, you either don't need to do that again, or you need to use utf-8 decoding.

You should read about foreach and map on how to work on an array without indexes (that's C-style for loops, with the idea of pointers not far behind). For example : print join "", map { chr((ord $_) ^ 255) } split //, $_; would do pretty much the same as your code, except for the encode part.