using System;

using System.Text.Json;

public class Program

{

    public static void Main()

    {

        Foo foo = new Foo { Data = new byte[] { 0x48, 0x49, 0x1d, 0x52, 0x53, 0x1d, 0x56, 0x57, 0x00 } };

        string json = JsonSerializer.Serialize(foo);

        Console.WriteLine(json); 

        Console.WriteLine();

        Foo fah = JsonSerializer.Deserialize<Foo>(json);

        DumpBytes(fah.Data);

        fah = JsonSerializer.Deserialize<Foo>("{\"Data\":[48, 49, 10, 52, 53, 10, 56, 57, 00 ]}");

        DumpBytes(fah.Data);

    }

    private static void DumpBytes(byte[] b)

    {

        for (int i = 0; i < b.Length; i++)

        {

            int c = b[i];

            Console.Write(c.ToString("X2") + " ");

        }

        Console.WriteLine();

    }

}

​

public class Foo

{

    public byte[] Data { get; set; }    

}

​