diff --git a/src/tea3.rs b/src/tea3.rs
index e90b7ff..1e63864 100644
--- a/src/tea3.rs
+++ b/src/tea3.rs
@@ -66,6 +66,17 @@ impl Tea3 {
         r7
     }
 
+    /// outputs the next cipher byte
+    pub fn next_byte(&mut self) -> u8 {
+        let mut kout: u8;
+        for _i in 1..19 {
+            kout = self.step_key_register();
+            self.step_state_register(kout);
+        }
+        kout = self.step_key_register();
+        self.step_state_register(kout)
+    }
+
     pub fn key_register(&self) -> &[u8] {
         &self.key_register
     }
@@ -318,4 +329,27 @@ mod tests {
         // 7=0, 8=0, 15=1, 16=1 -> 0011 = 0x3
         assert_eq!(out[4], 0b0011);
     }
+
+    #[test]
+    fn test_state_register_step() {
+        let mut tea3 = Tea3::new(vec![0; 10], vec![1, 2, 3, 4, 5, 6, 7, 8]);
+
+        let kout = 0xAA;
+
+        let r7_before = tea3.state_register()[7];
+
+        let out = tea3.step_state_register(kout);
+
+        assert_eq!(out, r7_before);
+
+        let s = tea3.state_register();
+
+        assert_eq!(s[1], 1);
+        assert_eq!(s[2], 2);
+        assert_eq!(s[3], 3);
+        assert_eq!(s[4], 4);
+
+        assert_ne!(s[0], 1);
+        assert_ne!(s[5], 5);
+    }
 }