Secure Storage area use

TinyCLR OS
1

I had some quick questions about the secure storage area.
1.) This area will be flashed with the app deployment I assume?
2.) Is this area made read-only when the device is locked?

I am just trying to understand how you intend it to be used. If I create the ability to write it in the app code so I can configure it initially, then I’d need a way to make it read only, or I’d have to configure then remove/disable the code to write it. My initial use for it is to store the application key for in-field update, but there are a couple other things I can do with it.

2
  1. No, only erased by:
  • Erase All from TinyClr Config or
  • E command from Bootloader
  • By user application.
    Deploy new app has no effect.
  1. Locked devices has no effect to user application. the app always have full access.
3

So basically I should create a simple configuration app that has a command set to set up this region over TCP/IP or something, then deploy the actual application code prior to shipping that doesn’t have the tools to access this region.

4

yes, you can do that.

5

I have been thinking about this area. What if someone needs this for more deployment? I think this storage should be optional.

1 Like
6

I think the best would be to make it configurable. If I have to flash an app to set it up in the first place, you might as well let me define the space I need for it. Not sure how hard that would be on your end, but 128 kb is pretty generous for the types of things I would store there. Using 256 bit encryption is only a 16 byte key. I can’t imagine applications requiring 8,000 keys, but I suppose its possible. So, instead of a checkbox that turns it on and off during deployment, can you make it a textbox that takes an int?!

7

there is a smaller region in rtc backup memory.

8

Great idea. That is better. RTC RAM. But if you lose it then you lose the key…hmmm

9

At the end of the day, I think that is the price of security. If the embedded loses the key, then you’ll just have to bite the bullet and replace the module. Good thing you make a socketed version so this is not a hugely expensive endeavor. The alternative, for me at least, is to create some commands that will flash an app using a provided key over a data line. Essentially, these commands just wouldnt be exposed to the outside world and held as secret internally. The likelihood of someone figuring out they exist, considering its all on-die ROM, is essentially non-existent. So, you can recover if the key gets lost.

10

Is there any way to access this area from PC?
I’ve tried this code:

using GHIElectronics.TinyCLR.Debugger.Management;
using System;

namespace ConsoleApp1
{
    class Program
    {
        private static MFDeploy mfdep;

        private static MFDevice mfdev;

        static void Main(string[] args)
        {
            Program.mfdep = new MFDeploy();

            var mfports = mfdep.EnumPorts(new TransportType[1] { TransportType.USB });
            if (mfports.Count >= 1)
            {
                if (mfports[0].Name.Contains("G120") || mfports[0].Name.Contains("20100") || mfports[0].Name.Contains("20260"))
                {
                    try
                    {
                        Program.mfdev = mfdep.Connect(mfports[0]);

                        MFConfigHelper cfg = new MFConfigHelper(mfdev);

                        var buf = cfg.FindConfig("test");

                        cfg.WriteConfig("test", new byte[] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 });

                        buf = cfg.FindConfig("test");
                    }
                    catch (Exception e)
                    {
                    }
                }
            }
        }
    }
}

and i’ve got this error:
‘cfg.WriteConfig(“test”, new byte[] {1,2,3,4,5})’ threw an exception of type ‘GHIElectronics.TinyCLR.Debugger.Management.MFConfigurationSectorOutOfMemoryException’
Data: {System.Collections.ListDictionaryInternal}
HResult: -2146233088
HelpLink: null
InnerException: null
Message: “Configuration sector is out of memory”
Source: “GHIElectronics.TinyCLR.Debugger”
StackTrace: " at GHIElectronics.TinyCLR.Debugger.Management.MFConfigHelper.WriteConfig(String configName, Byte[] data, Boolean staticSize, Boolean updateConfigSector)\r\n at GHIElectronics.TinyCLR.Debugger.Management.MFConfigHelper.WriteConfig(String configName, Byte[] data)"
TargetSite: {Void WriteConfig(System.String, Byte[], Boolean, Boolean)}

11

You can if you implement access in your application, like over USB or network

12

I see. So old methods won’t work and I need to implement custom handler on the board? Can you please suggest me the right path to implement it over USB? USB CDC with mode selection or anything else which I don’t know? Thank you