Summary:
* padding accepts everything that decrypts to `00 02 xx xx .. xx 00 `* `make_executable` marks the ciphertext as executable as well
Build a ciphertext of the form `90 90 .. 90 <shellcode> <padding>`, such that it decrypts to `00 02 xx .. xx 00 eb XX ...`, where `eb XX` is a near jump that lands in the NOP sled.