How to Decrypt the payload on server during authorization and map to model in web api

I've been trying to follow this answer trying to decrypt the Encrypted payload during the Authorization before it gets model mapped to the controller.

From the client only the Payload will be encrypted and on the server side I'm trying to decrypt. Thing is the entire Response.content cannot be decrypted as only the payload needs to decrypted.

Inside the content we're receiving the payload in Result and when I'm trying to change that it is showing that it is read only and I couldn't see any other options. In the image above the result is not encrypted yet, I was testing to see if we can change that.

I've done it in another way where I'll be passing the entire encrypted string to the controller and then decrypting it and mapping to model inside the controller like this:

        [Route("api/xxxxxx")]
        [HttpPost]
        public HttpResponseMessage PostTest(string encryptedValue)
        {
            //creating an instance of class
            HttpResponseMessage response = new HttpResponseMessage();
            
            try
            {
               string decryptJson = AES.DecryptString(encryptedValue);
               Model list = JsonConvert.DeserializeObject<Model>(decryptJson);
               
               //rest of the operation


            }
            //to catch exceptions if any
            catch (Exception ex)
            {
                output.Success = false;
                output.Message = Literals.GetErrorMessage(ex.Message);
            }
            //creating response
            response = Request.CreateResponse(HttpStatusCode.OK, JObject.FromObject(output));

            //returning response
            return response;
        }

This is working as expected but I'm trying if at all it's possible to do this at Authorization instead of doing it individually to every controller.

Any advice is appreciated.

Using new StringContent() to add the decrypted string to the Response.Content:

public class LogAttribute : AuthorizeAttribute
    {

        public override void OnAuthorization(HttpActionContext actionContext)
        {
            try
            {
               var resoponseContent = actionContext.Request.Content.ReadAsStringAsync();

                var result = resoponseContent.Result;

                var decryptedString = AESEncryptDecrypt.DecryptStringAES(result);

                actionContext.Request.Content = new StringContent(decryptedString, Encoding.UTF8, "application/json");

                var checkingDecryptedResponseContent = actionContext.Request.Content.ReadAsStringAsync();

            }
            catch (Exception ex)
            {
            }
        }
    }

After updating the new content the Model will be auto mapped to the controller.

        [LogAttribute]
        [Route("api/xxxxxx")]
        [HttpPost]
        public HttpResponseMessage PostTest(Model data)
        {
            //creating an instance of class
            HttpResponseMessage response = new HttpResponseMessage();
            
            try
            {
               
               //rest of the operation

            }
            //to catch exceptions if any
            catch (Exception ex)
            {
                output.Success = false;
                output.Message = Literals.GetErrorMessage(ex.Message);
            }
            //creating response
            response = Request.CreateResponse(HttpStatusCode.OK, JObject.FromObject(output));

            //returning response
            return response;
        }