public class MyClass
{
   public byte[] Bytes{get;set;}
}

MyClass obj = new MyClass();
obj.Bytes = new byte[]{1,22,44,55};

string s_result = Newtonsoft.Json.JsonConvert.SerializeObject(obj);

// my s_result looks like {"Bytes":"KQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA="}

public class MyClass
    {
       [JsonIgnore]
       public byte[] Bytes{get;set;}
       public int[] MessageByte
        {
            get
            {
              if (this.Bytes == null)
                return null;
                int[] result = new int[this.Bytes.Length];
                for (int i = 0; i < this.Bytes.Length; i++)
                {
                    result[i] = this.Bytes[i];
                }
                return result;
            }
        }

    }