embellished readme

README

@@ -55,3 +55,24 @@ A GENETIC ROP-CHAIN DEVELOPMENT TOOL
 Genetic programming platform for evolving ROP-chain payloads,
 implemented in Rust. Under construction.
 
+                          BRIEF EXPLANATION
+
+ROPER is a genetic ROP-chain compiler that I have designed and developed. It
+compiles ROP-chains, by creating a miniature ecosystem in which ROP-chains
+evolve.  ROPER can be used to develop payloads -- including payloads that
+exhibit learned or evolved behaviour -- unlikely to be developed by humans.
+
+Definitions:
+
+1. Return-Oriented Programming is an exploit technique that, instead of writing
+malicious code ("shellcode") into a process' executable memory, collages
+together a series of "gadgets" that already subside in executable memory. This
+is useful when the process has no memory segments that are flagged as both
+executable and writeable (W^X/DEP). 
+
+2. Genetic programming is the implementation of natural selection in code.  A
+population of random programmes (in this case, ROP-chains) is generated. A
+fitness function is then defined, and used to rank the results of their
+execution. Fitter programmes are made more likely to breed. Mutation operators
+are applied to the offspring, and the next generation of the process begins.
+This carries on until the desired outcome is obtained. 

src/roper/util.rs

@@ -181,6 +181,16 @@ pub fn mang (ux: u32, rng: &mut ThreadRng) -> u32 {
     18 => x >> 2,
     19 => x >> 4,
     20 => rng.gen::<i32>(),
+    21 => x ^ (1 << (rng.gen::<usize>() % 32)), // random bit flip
+    22 => x ^ (1 << (rng.gen::<usize>() % 32)), // random bit flip
+    23 => x ^ (1 << (rng.gen::<usize>() % 32)), // random bit flip
+    24 => x ^ (1 << (rng.gen::<usize>() % 32)), // random bit flip
+    25 => x ^ (1 << (rng.gen::<usize>() % 32)), // random bit flip
+    26 => x ^ (1 << (rng.gen::<usize>() % 32)), // random bit flip
+    27 => x ^ (1 << (rng.gen::<usize>() % 32)), // random bit flip
+    28 => x ^ (1 << (rng.gen::<usize>() % 32)), // random bit flip
+    29 => x ^ (1 << (rng.gen::<usize>() % 32)), // random bit flip
+    30 => x ^ (1 << (rng.gen::<usize>() % 32)), // random bit flip
     _  => x,
   };
   r as u32