[qmc2/rc4] refactor: create box of slice instead of convert later

um_crypto/qmc/src/v2_rc4/cipher.rs

@@ -17,13 +17,13 @@ pub struct QMC2RC4 {
 impl QMC2RC4 {
     pub fn new(key: &[u8]) -> Self {
         let mut rc4 = RC4::new(key);
-        let mut key_stream = [0u8; RC4_STREAM_CACHE_SIZE];
-        rc4.derive(&mut key_stream);
+        let mut key_stream = Box::new([0u8; RC4_STREAM_CACHE_SIZE]);
+        rc4.derive(&mut key_stream[..]);
 
         Self {
             hash: hash(key),
             key: key.into(),
-            key_stream: key_stream.into(),
+            key_stream,
         }
     }
 

um_crypto/qmc/src/v2_rc4/rc4.rs

@@ -42,8 +42,11 @@ impl RC4 {
         self.state[index]
     }
 
-    pub fn derive(&mut self, buffer: &mut [u8]) {
-        for item in buffer.iter_mut() {
+    pub fn derive<T>(&mut self, buffer: &mut T)
+    where
+        T: AsMut<[u8]> + ?Sized,
+    {
+        for item in buffer.as_mut().iter_mut() {
             *item ^= self.generate();
         }
     }