[erglkjahlkh]

Also, does the scheme unencrypt the code to be run into what memory segment? What does this technique mean for current memory protection methods?

We do have nowadays non-executable stack, and heap by default. In fact, only the marked read only segments can contain runnable code, unless if you use specific workarounds. What happens if the code you are protecting and running is more complex, requiring calls where you would usually use position independence and stuff like ASLR to full extend? Do you lose these the benefits or those features, or is there necessary information leak (take a look at plt for instance)?

To add to this that in the end of the day if you can access both the data and the key it is just highly complex obfuscation, I am hardly impressed.