I worked on OpenTitan for around 5 years at lowRISC. It certainly has its ups and downs but it's generated some great stuff and I'm very glad to see hit proper volume production like this. Whilst there's definitely open source chips out there and lots more using bits of open source that don't actually advertise this fact I believe this is the first chip with completely open RTL that's in a major production volume use case.
One of highlights working on OpenTitan was the amount of interest we got from the academic community. Work they did could actually get factored into the first generation silicon making it stronger. Ordinarily chips like that are kept deeply under wraps and the first time the wider security community can take a look at them development has long completed so anything they might find could only effect generation 2 or 3 of the device.
Academic collaboration also helped get ahead in post quantum crypto. This first generation chip has limited capabilities there but thanks to multiple academics using the design as a base for their own PQC work there was lots to draw on for future designs.
I'm no longer at lowRISC so I don't know where OpenTitan is going next but I look forward to finding out.
> Ibex® is a small and highly configurable open-source RISC-V embedded processor available under an Apache 2.0 licence. It is formally verified and very well validated, and it has excellent toolchain integration, which has led many companies to use it in their commercial SoCs.
> [...]
> Ibex is the main CPU in the OpenTitan® root of trust, which has brought the quality of the design and documentation to new heights.
I'm not seeking to criticise this product, I think this is a great development.
But, for almost all people this is shifting from one kind of "trust me bro" to .. another. We're not going to be able to formally prove the chip conforms to some (verilog?) model, has no backdoors, side channels, you-name-it. We're in the same place we were, with the same questions. Why do we trust this and the downstream developments? Because we do.
I know people who worked on cryptech, and I definitely had trust in their work, personal commitment to what they did, but that's "who you know" trust. The non transitive quality of this kind of trust is huge.
To be more critical my primary concern will be how deployment of this hardware is joined by significantly less benign design choices like locked bootloaders, removal of sideloads. To be very clear that's a quite distinct design choice, but I would expect to see it come along for the ride.
To be less critical, will this also now mean we get good persisting on device credentials and so can do things like X.509 certs for MAC addresses and have device assurance on the wire? Knowing you are talking to the chipset which signed the certificate request you asserted to before shipping is useful.
Take a look at how Matter handles this; manufacturer certificate to vouch for hardware integrity which gets superceded by the fabric's root CA on commissioning (enrollment in the fabric).
This is basically the best we can hope for until we get nanofabs at home and can build our own secure enclaves in our garages.
Trust decision theory goes like this; it it were possible for the manufacturer to fully control the device then competitors would not use it, so e.g. wide industry adoption of OpenTitan would be evidence of its security in that aspect. Finally, if devices had flaws that allowed them to be directly hacked or their keys stolen then demonstrating it would be straightforward and egg on the face of the manufacturer who baked their certificate on the device.
Final subject; 802.1x and other port-level security is mostly unnecessary if you can use mTLS everywhere which is what ubiquitous hardware roots of trust allows. Clearly it will take a while for the protocol side to catch up; but I hope that eventually we'll be running SPIFFE or something like it at home.
> To be more critical my primary concern will be how deployment of this hardware is joined by significantly less benign design choices like locked bootloaders, removal of sideloads. To be very clear that's a quite distinct design choice, but I would expect to see it come along for the ride.
A justifiable concern, given sentences like "strongest possible security guarantees that the code being executed is authorized and verified" and "can be used across the Google ecosystem and also facilitates the broader adoption of Google-endorsed security features across the industry"
This is really great. OpenTitan has some useful IP components that can definitely be reused, and it's really cool that this is open. Nice one Google. I have to minority nitpick though:
> both individual IP blocks and the top-level Earl Grey design have functional and code coverage above 90%—to the highest industry standards—with 40k+ tests running nightly
This is definitely not "to the highest industry standards". I've worked on projects where we got to 100% on both for most of the design. It's definitely a decent commercial standard though - way above most open source verification quality.
I worked on OpenTitan for around 5 years at lowRISC. It certainly has its ups and downs but it's generated some great stuff and I'm very glad to see hit proper volume production like this. Whilst there's definitely open source chips out there and lots more using bits of open source that don't actually advertise this fact I believe this is the first chip with completely open RTL that's in a major production volume use case.
One of highlights working on OpenTitan was the amount of interest we got from the academic community. Work they did could actually get factored into the first generation silicon making it stronger. Ordinarily chips like that are kept deeply under wraps and the first time the wider security community can take a look at them development has long completed so anything they might find could only effect generation 2 or 3 of the device.
Academic collaboration also helped get ahead in post quantum crypto. This first generation chip has limited capabilities there but thanks to multiple academics using the design as a base for their own PQC work there was lots to draw on for future designs.
I'm no longer at lowRISC so I don't know where OpenTitan is going next but I look forward to finding out.
Clicking through links eventually led to https://lowrisc.org/ibex/ -
> Ibex® is a small and highly configurable open-source RISC-V embedded processor available under an Apache 2.0 licence. It is formally verified and very well validated, and it has excellent toolchain integration, which has led many companies to use it in their commercial SoCs.
> [...]
> Ibex is the main CPU in the OpenTitan® root of trust, which has brought the quality of the design and documentation to new heights.
So that's neat.
I'm not seeking to criticise this product, I think this is a great development.
But, for almost all people this is shifting from one kind of "trust me bro" to .. another. We're not going to be able to formally prove the chip conforms to some (verilog?) model, has no backdoors, side channels, you-name-it. We're in the same place we were, with the same questions. Why do we trust this and the downstream developments? Because we do.
I know people who worked on cryptech, and I definitely had trust in their work, personal commitment to what they did, but that's "who you know" trust. The non transitive quality of this kind of trust is huge.
To be more critical my primary concern will be how deployment of this hardware is joined by significantly less benign design choices like locked bootloaders, removal of sideloads. To be very clear that's a quite distinct design choice, but I would expect to see it come along for the ride.
To be less critical, will this also now mean we get good persisting on device credentials and so can do things like X.509 certs for MAC addresses and have device assurance on the wire? Knowing you are talking to the chipset which signed the certificate request you asserted to before shipping is useful.
Take a look at how Matter handles this; manufacturer certificate to vouch for hardware integrity which gets superceded by the fabric's root CA on commissioning (enrollment in the fabric).
This is basically the best we can hope for until we get nanofabs at home and can build our own secure enclaves in our garages.
Trust decision theory goes like this; it it were possible for the manufacturer to fully control the device then competitors would not use it, so e.g. wide industry adoption of OpenTitan would be evidence of its security in that aspect. Finally, if devices had flaws that allowed them to be directly hacked or their keys stolen then demonstrating it would be straightforward and egg on the face of the manufacturer who baked their certificate on the device.
Final subject; 802.1x and other port-level security is mostly unnecessary if you can use mTLS everywhere which is what ubiquitous hardware roots of trust allows. Clearly it will take a while for the protocol side to catch up; but I hope that eventually we'll be running SPIFFE or something like it at home.
> To be more critical my primary concern will be how deployment of this hardware is joined by significantly less benign design choices like locked bootloaders, removal of sideloads. To be very clear that's a quite distinct design choice, but I would expect to see it come along for the ride.
A justifiable concern, given sentences like "strongest possible security guarantees that the code being executed is authorized and verified" and "can be used across the Google ecosystem and also facilitates the broader adoption of Google-endorsed security features across the industry"
"OpenTitan is the first commercially available open source RoT to support post-quantum cryptography (PQC) secure boot"
This is really great. OpenTitan has some useful IP components that can definitely be reused, and it's really cool that this is open. Nice one Google. I have to minority nitpick though:
> both individual IP blocks and the top-level Earl Grey design have functional and code coverage above 90%—to the highest industry standards—with 40k+ tests running nightly
This is definitely not "to the highest industry standards". I've worked on projects where we got to 100% on both for most of the design. It's definitely a decent commercial standard though - way above most open source verification quality.