period finder update

src/period.rs

@@ -140,24 +140,8 @@ fn period_h(start: Reg5) -> u64 {
 
 /// paper method, decomposition key register
 /// (Observations on TETRA Encryption Algorithm TEA-3)
+/// key 5 bytes, (10 bytes but first 5 bytes are padding with 0)
 pub fn period_paper(key: Vec<u8>) -> u64 {
-    let start = Decomposed::from_key(&key);
-
-    let p = period_h(start.h);
-
-    for mult in [1u64, 2, 5, 10] {
-        let target = p * mult;
-
-        let mut cur = start;
-
-        for _ in 0..target {
-            cur.step();
-        }
-
-        if cur == start {
-            return target;
-        }
-    }
-
-    panic!("No valid period found");
+    let start = Decomposed::from_key(&[0, 0, 0, 0, 0, key[0], key[1], key[2], key[3], key[4]]);
+    period_h(start.h) // p
 }