<html class="apple-mail-supports-explicit-dark-mode"><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto">This is a fascinating discussion I would never have guessed would be on this list.<br id="lineBreakAtBeginningOfSignature"><div dir="ltr">Benjamin Tremblay</div><div dir="ltr"><br><blockquote type="cite">On Sep 10, 2026, at 4:13 PM, David Kantowitz via Synth-diy <synth-diy@synth-diy.org> wrote:<br><br></blockquote></div><blockquote type="cite"><div dir="ltr"><div dir="ltr">Not really. Search for "secure microcontroller" at the NXP website. The detailed manuals (at least for NXP) usually require an NDA w/ NXP, but a 2-page summary sales sheet should be available. <div><br></div><div>A lot of microcontrollers (not just NXP) have features like: 'secure boot', 'secure element', 'secure memory', 'trusted module', 'trusted execution', etc. ARM has TrustZone that a lot of manufacturers use. Some combination of those features could do what you want.</div><div><br></div><div>Honestly, it's a bit hard to point you in the right direction without understanding what you actually want to do. ... and based on my earlier emails, what you described as wanting to do doesn't really make sense to me in a commercial context. There are significant costs involved in building even vaguely secure hardware. An example of the stupid shit that happens ... units were keyed at Key Injection Facility, then shipped to the user site, units started to arrive in the tamper state with no keys .. queue 6 month parade of units back and forth ... eventually we figure out that a software bug wasn't putting the cpu into a low enough sleep state and the supercap keeping the keys alive was drained in transit. I can't even bear to describe how stupid the spares situation became.</div><div><br></div><div><br></div></div><br><div class="gmail_quote gmail_quote_container"><div dir="ltr" class="gmail_attr">On Thu, Sep 10, 2026 at 11:51 AM cheater cheater <<a href="mailto:cheater00social@gmail.com">cheater00social@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Thanks, David. That's some good info. Can you point to some recent<br>
devices that are available on the market?<br>
<br>
On Thu, Sep 10, 2026 at 7:22 PM David Kantowitz <<a href="mailto:dkantowitz@gmail.com" target="_blank">dkantowitz@gmail.com</a>> wrote:<br>
><br>
> BOM cost was single digit USD. Essentially it was a way to audit licensing fees through an electronic component based supply chain.<br>
><br>
> What you're describing are key rolling and key injection. You can look at current practices for payment terminals, but honestly those are made-by-committee unions of the individual company's own practices.<br>
><br>
> We used two basic approaches to secure the cryptographic root:<br>
> 1. 'Base' key injection key that's used only to load site-deployment keys. Those keys were secured by obscurity. "Steganographic methodology" when we wanted to sound like experts.<br>
> 2. Shipping units to a secure key injection facility. Use tamper evident bags when you want a fancy audit trail.<br>
><br>
> Site keys are stored in something physically tamper-proof. As a simple example (ie. what was done 20 years ago):<br>
> - make a PCB sandwich. all components on inside, no traces on outside of PCB. single power & serial port on outside. a plastic ring goes around the edge. bolot he sandwich together.<br>
> - electrical connection between the two boards via pin headers<br>
> - put key in static RAM (not flash, not DRAM)<br>
> - SRAM on board A, battery on board B<br>
> If someone opens the sandwich and the site keys lose power. Back to (1) or (2) above to restore site keys.<br>
><br>
> Despite having microcontrollers with secure memory, much more physically complicated versions of the sandwich are still used today:<br>
> (A) Detect the tamper. (B) Destroy the keys. (C) Restore the keys.<br>
><br>
> Separately, everyone also builds in some method for key-rolling into their systems. This handles the scenario you described: you believe the keys were actually stolen with malicious intent. Personally, I've gone through customer witnessed testing of the key rolling, I've never seen a live system do a key roll. It was simply too risky. Instead we would maintain blacklists of cards & equipment. This requires a system that is frequently online.<br>
><br>
> On Thu, Sep 10, 2026 at 9:20 AM cheater cheater <<a href="mailto:cheater00social@gmail.com" target="_blank">cheater00social@gmail.com</a>> wrote:<br>
>><br>
>> I agree that the DRM is just one component of an otherwise healthy<br>
>> business strategy.<br>
>><br>
>> Do you remember how much roughly the NXP chips added to your BOM?<br>
>><br>
>> > This seems to be the arc of most cryptographically enabled DRM.<br>
>><br>
>> I agree. I know about power monitoring, power glitching, and various<br>
>> other hardware attacks.<br>
>><br>
>> One thing that I'm curious about is things like updating encryption,<br>
>> in order to be able to repudiate compromised keys, eg from<br>
>> manufacturers who have decided to start leaking them to companies who<br>
>> shouldn't have them. This would at least require some sort of secure<br>
>> vault with a machine of some sort inside, probably a VM.<br>
>><br>
>> Cheers,<br>
>> D<br>
>><br>
>> On Thu, Sep 10, 2026 at 6:09 PM David Kantowitz <<a href="mailto:dkantowitz@gmail.com" target="_blank">dkantowitz@gmail.com</a>> wrote:<br>
>> ><br>
>> > The closest "on topic" experiences I have are with the contactless payment (and ID) cards.<br>
>> ><br>
>> > To read/write Mifare cards, we had to include the Philips (now NXP) reader chip in our equipment: even though our own DSP/FPGA generated the RF modulation signals and we had our own implementation of the on-air data protocol stack.<br>
>> ><br>
>> > All the Philips chip contained was their proprietary shared-secret encryption algorithm.<br>
>> ><br>
>> > Two things happened over time:<br>
>> > 1. Researchers reverse engineered/discovered and published the exact proprietary cryptographic algorithm.<br>
>> > 2. Various key recovery techniques were possible through either defects in the protocol implementation or techniques like power monitoring (which you can also think of as an implementation defect).<br>
>> ><br>
>> > This seems to be the arc of most cryptographically enabled DRM.<br>
>> ><br>
>> > The Philips chips were generally easy to use and the integration cost was more a one-time expense. Still they added to the BOM cost.<br>
>> ><br>
>> > Even after the system was broken we continued to use them: it was the easiest way to vouch to our customers that our equipment was compatible with Mifare cards. That compatibility was necessary because, by then, out customers had money sunk (ie. millions) into cards.<br>
>> ><br>
>> > Briefly off topic: that 10+ year experience taught me that DRM-like capabilities are small (nearly irrelevant) technical components in a broader commercial strategy ; figure out the strategy first and then use DRM as a temporary stepping stone in that strategy.<br>
>> ><br>
>> ><br>
>> ><br>
>> > On Thu, Sep 10, 2026 at 12:41 AM cheater cheater via Synth-diy <<a href="mailto:synth-diy@synth-diy.org" target="_blank">synth-diy@synth-diy.org</a>> wrote:<br>
>> >><br>
>> >> David, Mike,<br>
>> >> Please start a separate thread, this isn't what this thread is about.<br>
>> >><br>
>> >> Thanks.<br>
>> >><br>
>> >> On Thu, Sep 10, 2026 at 8:58 AM David Huss via Synth-diy<br>
>> >> <<a href="mailto:synth-diy@synth-diy.org" target="_blank">synth-diy@synth-diy.org</a>> wrote:<br>
>> >> ><br>
>> >> > The idea to do some sort of multichannel modular via digital cables is not exactly new and not exactly something that isn't obvious.<br>
>> >> ><br>
>> >> > Technically such a thing is already done with ADAT/Toslink optical cables and many audio interfaces use it to allow users to add more I/O channels.<br>
>> >> ><br>
>> >> > So the main obvious question is why we haven't seen something like this widely used in the modular world?<br>
>> >> ><br>
>> >> > To me the answer is that the simplicity of the concept is unbeatable: Everything is just a voltage versus time, one signal per cable, what you see is what you get. All while being reliable, cheap to implement, cables are cheap, clocking is not an issue, it is conceptually clear, etc.<br>
>> >> ><br>
>> >> > The two useful applications of multi-channel cables I see are: (1) polyphonic modules where patching up 4+ cables is annoying and takes up valuable panel space and (2) breakout boxes for multichannel connections between racks (e.g. via Ethernet).<br>
>> >> ><br>
>> >> > Of course I could envision cool systems with multi-channel cables, but I am not sure it is really worth the extra complexity to make them digital. By that point one can ask, why not just run everything on a computer and make a patch-cable controller panel that just reads out the patch connections, knob positions etc and controls a big virtual modular.<br>
>> >> ><br>
>> >> > On September 9, 2026 11:44:34 PM UTC, Gordonjcp <<a href="mailto:gordonjcp@gjcp.net" target="_blank">gordonjcp@gjcp.net</a>> wrote:<br>
>> >> > >On Wed, Sep 09, 2026 at 07:31:21PM +0200, cheater cheater via Synth-diy wrote:<br>
>> >> > >><br>
>> >> > >> So, there's good news and bad news. The bad news is that I can't go<br>
>> >> > >> into specifics, but there are good reasons to expect a new modular<br>
>> >> > >> format showing up sometime in the not extremely distant future.<br>
>> >> > ><br>
>> >> > >Good luck with that.<br>
>> >> > ><br>
>> >> > >How did you get one with your polyphonic modular idea with 24 channels of 24-bit 192kHz CV on a single 3.5mm jack?<br>
>> >> > ><br>
>> >> ><br>
>> >> > ________________________________________________________<br>
>> >> > This is the Synth-diy mailing list<br>
>> >> > Submit email to: <a href="mailto:Synth-diy@synth-diy.org" target="_blank">Synth-diy@synth-diy.org</a><br>
>> >> > View archive at: <a href="https://synth-diy.org/pipermail/synth-diy/" rel="noreferrer" target="_blank">https://synth-diy.org/pipermail/synth-diy/</a><br>
>> >> > Check your settings at: <a href="https://synth-diy.org/mailman/listinfo/synth-diy" rel="noreferrer" target="_blank">https://synth-diy.org/mailman/listinfo/synth-diy</a><br>
>> >> > Selling or trading? Use <a href="mailto:marketplace@synth-diy.org" target="_blank">marketplace@synth-diy.org</a><br>
>> >><br>
>> >> ________________________________________________________<br>
>> >> This is the Synth-diy mailing list<br>
>> >> Submit email to: <a href="mailto:Synth-diy@synth-diy.org" target="_blank">Synth-diy@synth-diy.org</a><br>
>> >> View archive at: <a href="https://synth-diy.org/pipermail/synth-diy/" rel="noreferrer" target="_blank">https://synth-diy.org/pipermail/synth-diy/</a><br>
>> >> Check your settings at: <a href="https://synth-diy.org/mailman/listinfo/synth-diy" rel="noreferrer" target="_blank">https://synth-diy.org/mailman/listinfo/synth-diy</a><br>
>> >> Selling or trading? Use <a href="mailto:marketplace@synth-diy.org" target="_blank">marketplace@synth-diy.org</a><br>
</blockquote></div>
<span>________________________________________________________</span><br><span>This is the Synth-diy mailing list</span><br><span>Submit email to: Synth-diy@synth-diy.org</span><br><span>View archive at: https://synth-diy.org/pipermail/synth-diy/</span><br><span>Check your settings at: https://synth-diy.org/mailman/listinfo/synth-diy</span><br><span>Selling or trading? Use marketplace@synth-diy.org</span><br></div></blockquote></body></html>