diff --git a/src/encrypt.rs b/src/encrypt.rs
index d733488..8e7fcad 100644
--- a/src/encrypt.rs
+++ b/src/encrypt.rs
@@ -37,14 +37,23 @@ impl McCipher {
     ) -> Result<Self> {
         let aes_key: [u8; 16] = decrypt_rsa(private_key, data)?
             .as_slice()[0..16].try_into().unwrap();
+        let mut key: [u8; 16] =
+            vec![0;16].as_slice()[0..16].try_into().unwrap();
+        key.copy_from_slice(&aes_key);
+        let mut state_en: [u8; 16] =
+            vec![0;16].as_slice()[0..16].try_into().unwrap();
+        state_en.copy_from_slice(&aes_key);
+        let mut state_de: [u8; 16] =
+            vec![0;16].as_slice()[0..16].try_into().unwrap();
+        state_de.copy_from_slice(&aes_key);
         Ok(Self {
-            key: aes_key.clone(),
-            state_en: aes_key.clone(),
-            state_de: aes_key.clone(),
+            key,
+            state_en,
+            state_de,
         })
     }
 
-    pub fn encrypt_aes(&self, data: Vec<u8>) -> Vec<u8> {
+    pub fn encrypt_aes(&mut self, data: Vec<u8>) -> Vec<u8> {
         let mut out_data = vec![0; data.len()];
         for i in 0..data.len() {
             out_data[i] = self.encrypt_block(data[i]);
@@ -52,7 +61,7 @@ impl McCipher {
         out_data
     }
 
-    pub fn decrypt_aes(&self, data: Vec<u8>) -> Vec<u8> {
+    pub fn decrypt_aes(&mut self, data: Vec<u8>) -> Vec<u8> {
         let mut out_data = vec![0; data.len()];
         for i in 0..data.len() {
             out_data[i] = self.decrypt_block(data[i]);
@@ -60,28 +69,32 @@ impl McCipher {
         out_data
     }
 
-    fn shift_left(mut arr: [u8; 16], new: u8) {
-        for i in 1..arr.len() {
-            arr[i] = arr[i - 1];
+    fn shift_left(arr: [u8; 16], new: u8) -> [u8; 16] {
+        let mut arr = arr;
+        for i in 0..arr.len() - 1 {
+            arr[i] = arr[i + 1];
         }
-        arr[0] = new;
+        arr[15] = new;
+        arr
     }
 
-    fn encrypt_block(&self, data: u8) -> u8 {
+    fn encrypt_block(&mut self, data: u8) -> u8 {
         let cipher = Aes128::new(GenericArray::from_slice(&self.key));
         let mut block = GenericArray::clone_from_slice(&self.state_en);
         cipher.encrypt_block(&mut block);
-        let data = data ^ block[15];
-        Self::shift_left(self.state_en, data);
+        let data = data ^ block[0];
+        self.state_en = Self::shift_left(self.state_en, data);
+        assert_ne!(self.state_en, self.key);
+        assert_ne!(self.state_en, self.state_de);
         data
     }
 
-    fn decrypt_block(&self, data: u8) -> u8 {
+    fn decrypt_block(&mut self, data: u8) -> u8 {
         let cipher = Aes128::new(GenericArray::from_slice(&self.key));
         let mut block = GenericArray::clone_from_slice(&self.state_de);
         cipher.decrypt_block(&mut block);
-        Self::shift_left(self.state_de, data);
-        let data = data ^ block[15];
+        self.state_de = Self::shift_left(self.state_de, data);
+        let data = data ^ block[0];
         data
     }
 }
diff --git a/src/mc_types.rs b/src/mc_types.rs
index 9a2517a..938de60 100644
--- a/src/mc_types.rs
+++ b/src/mc_types.rs
@@ -235,7 +235,7 @@ unsafe impl<'a> Send for ProtocolConnection<'a> {}
 #[async_trait]
 impl<'a> ProtocolRead for ProtocolConnection<'a> {
     async fn read_data(&mut self) -> Result<Vec<u8>> {
-        match &self.aes_cipher {
+        match &mut self.aes_cipher {
             Some(aes_cipher) => {
                 let length = read_var_int_stream_encrypted(
                     self.stream_read, aes_cipher).await? as usize;
@@ -262,7 +262,7 @@ impl<'a> ProtocolWrite for ProtocolConnection<'a> {
     async fn write_data(&mut self, data: &mut Vec<u8>) -> Result<()> {
         let mut out_data = convert_var_int(data.len() as i32);
         out_data.append(data);
-        match &self.aes_cipher {
+        match &mut self.aes_cipher {
             Some(aes_cipher) => {
                 self.stream_write.write_all(
                     &aes_cipher.encrypt_aes(out_data)).await?;
@@ -301,7 +301,7 @@ impl<'a> ProtocolWrite for WriteHaftProtocolConnection<'a> {
     async fn write_data(&mut self, data: &mut Vec<u8>) -> Result<()> {
         let mut out_data = convert_var_int(data.len() as i32);
         out_data.append(data);
-        match &self.aes_cipher {
+        match &mut self.aes_cipher {
             Some(aes_cipher) => {
                 self.stream_write.write_all(
                     &aes_cipher.encrypt_aes(out_data)).await?;
@@ -350,7 +350,7 @@ unsafe impl<'a> Send for ReadHaftProtocolConnection<'a> {}
 #[async_trait]
 impl<'a> ProtocolRead for ReadHaftProtocolConnection<'a> {
     async fn read_data(&mut self) -> Result<Vec<u8>> {
-        match &self.aes_cipher {
+        match &mut self.aes_cipher {
             Some(aes_cipher) => {
                 let length = read_var_int_stream_encrypted(
                     self.stream_read, aes_cipher).await? as usize;
@@ -412,17 +412,17 @@ async fn read_var_int_stream(stream: &mut OwnedReadHalf) -> Result<i32> {
 }
 async fn read_var_int_stream_encrypted(
     stream: &mut OwnedReadHalf,
-    cipher: &McCipher,
+    cipher: &mut McCipher,
 ) -> Result<i32> {
     let mut data: Vec<u8> = vec![];
 
     loop {
         let encrypted_byte = stream.read_u8().await?;
-        let mut current_byte = cipher.decrypt_aes(vec![encrypted_byte]);
+        let current_byte = cipher.decrypt_aes(vec![encrypted_byte])[0];
 
-        data.append(&mut current_byte);
+        data.append(&mut vec![current_byte]);
 
-        if (current_byte[0] & CONTINUE_BIT) == 0 {
+        if (current_byte & CONTINUE_BIT) == 0 {
             break;
         }
     }