Finish challenge 20 statistical CTR.

src/set1.rs

@@ -138,17 +138,16 @@ pub fn challenge6() {
         result
     }
 
-    fn guess_key(bytes: &Bytes) -> u8 {
-        let mut h: Vec<(Bytes, u8)> = (0..=255).map(|i| (Bytes::xor_byte(bytes, i), i)).collect();
-        h.sort_by(|a, b| a.0.ascii_score().partial_cmp(&b.0.ascii_score()).unwrap());
-        h.last().unwrap().1
-    }
-
     _test_roundtrip();
     let bytes = read("data/6.txt");
     let key_size = guess_key_size(&bytes);
     let bytes_tranposed = transpose(&bytes, key_size);
-    let key = Bytes(bytes_tranposed.iter().map(|b| guess_key(&b)).collect());
+    let key = Bytes(
+        bytes_tranposed
+            .iter()
+            .map(|b| Bytes::guess_key(&b))
+            .collect(),
+    );
     let msg = Bytes::xor_cycle(&bytes, &key).to_utf8();
 
     let partial_msg = msg[..20].to_string();