diff --git a/contracts/src/contracts/mailbox.cairo b/contracts/src/contracts/mailbox.cairo
index 6d2f797..037a7d8 100644
--- a/contracts/src/contracts/mailbox.cairo
+++ b/contracts/src/contracts/mailbox.cairo
@@ -127,6 +127,8 @@ pub mod mailbox {
         pub const INSUFFICIENT_BALANCE: felt252 = 'Insufficient balance';
         pub const INSUFFICIENT_ALLOWANCE: felt252 = 'Insufficient allowance';
         pub const NOT_ENOUGH_FEE_PROVIDED: felt252 = 'Provided fee < needed fee';
+        pub const SIZE_DOES_NOT_MATCH_MESSAGE_BODY: felt252 = 'Size does not match msg body';
+        pub const SIZE_DOES_NOT_MATCH_METADATA: felt252 = 'Size does not match metadata';
     }
 
     #[constructor]
@@ -249,10 +251,16 @@ pub mod mailbox {
                 Option::None(()) => self.default_hook.read(),
             };
             let hook_metadata = match _custom_hook_metadata {
-                Option::Some(hook_metadata) => hook_metadata,
+                Option::Some(hook_metadata) => {
+                    let mut sanitized_bytes_metadata = BytesTrait::new_empty();
+                    sanitized_bytes_metadata.concat(@hook_metadata); 
+                    assert(sanitized_bytes_metadata ==hook_metadata, Errors::SIZE_DOES_NOT_MATCH_METADATA);
+                    hook_metadata},
                 Option::None(()) => BytesTrait::new_empty()
             };
-
+            let mut sanitized_bytes_message_body = BytesTrait::new_empty();
+            sanitized_bytes_message_body.concat(@_message_body);
+            assert(sanitized_bytes_message_body ==  _message_body, Errors::SIZE_DOES_NOT_MATCH_MESSAGE_BODY);
             let (id, message) = build_message(
                 @self, _destination_domain, _recipient_address, _message_body
             );
@@ -336,6 +344,15 @@ pub mod mailbox {
         /// * `_metadata` - Metadata used by the ISM to verify `_message`.
         /// * `_message` -  Formatted Hyperlane message (ref: message.cairo) 
         fn process(ref self: ContractState, _metadata: Bytes, _message: Message) {
+
+            
+            let mut sanitized_bytes_metadata = BytesTrait::new_empty();
+            sanitized_bytes_metadata.concat(@_metadata); 
+            assert(sanitized_bytes_metadata ==_metadata, Errors::SIZE_DOES_NOT_MATCH_METADATA);
+            let mut sanitized_bytes_message_body = BytesTrait::new_empty();
+            sanitized_bytes_message_body.concat(@_message.body);
+            assert(sanitized_bytes_message_body ==  _message.body, Errors::SIZE_DOES_NOT_MATCH_MESSAGE_BODY);
+
             assert(_message.version == HYPERLANE_VERSION, Errors::WRONG_HYPERLANE_VERSION);
             assert(
                 _message.destination == self.local_domain.read(), Errors::UNEXPECTED_DESTINATION