The fourth Silicon Salon, on May 3, 2023, offered a potpurri of topics, filling in some of the gaps from our first year of community work. This included presentations on how to ensure a hardware wallet is avoiding key leakage and how we can better enable biginteger operations in silicon. There was also a presentation and discussion on a topic that goes back to Silicon Salon 1: integrating the open-source ethos withe semiconductor work (and whether that’s possible at all!).
The fourth Silicon Salon featured three presentations, from Andrew Poelstra, from Luke Kenneth Casson Leighton, and from Cramium Labs. There were also question & answer sessions after each presentation.
Andrew Poelstra Presentation
Signatures: “You can think of an elliptic curve (EC) signature either ECDSA or Schnorr being a linear equation in two secret pieces of data.”
Key Exfil: “One immediate consequence of this is that if you don’t generate a new nonce and you reuse a nonce from a previous signature you used, then someone can invert the matrix and solve this and do a direct computation to get your secret key.”
Anti-Exfil: “What’s my solution? It takes the multisig premise here which is that you have two participants and they mix their randomness in together and they avoid biases.”
- Article — https://blog.blockstream.com/anti-exfil-stopping-key-exfiltration/
- Chosen Nonce Attack Workbook - https://github.com/stepansnigirev/chosen_nonce_demo/blob/master/HD_key.ipynb
Luke Leighton & David Calderwood Presentation
ISA Work: “Libre-SOC is researching and designing instructions which will be proposed to the OpenPOWER ISA working group for official inclusion in the Power ISA.”
Instructions: “We want everything to be general purpose. We want general purpose instructions that end up in mainstream compilers and the mainstream software toolchains and libraries.”
The Plan: “The initial concept was the usual 1-bit carry-in and carry-out and then extend it to 64-bits. The result is that you get, for free, a scalar vector arithmetic and you can do simple loops on top of that and then you have Knuth algorithms D and M.”
How It Works: “You’re just outputting the second half of what is normally thrown away as the carry-out.”
- Biginteger Analysis — https://libre-soc.org/openpower/sv/biginteger/analysis/
- RFC ls003 Big Integer — https://libre-soc.org/openpower/sv/rfc/ls003/
- Open Titan — https://opentitan.org/book/hw/ip/otbn/doc/isa.html
Cramium Labs Presentation
The IP Question: “Does copyright apply to hardware? What about chips?”
Maskwork: “This is only one design artifact used in making a chip and it has its own one-off right of its own.”
Complexity of Silicon IP: “I don’t expect you to absorb all these details. But there are many stages and they involve varying third-party IP.”
Copyleft Problems: “If you make a product that combines something that has a copyleft license and a proprietary license, then in some cases the boundary of licensing might expand to include the proprietary code.”
An Open Question: “What is the purpose of open-source hardware? Why do we think it’s desirable?”
Cramium’s Approach: “Our approach, subject to change, is that we’re building a chip and we’re publishing an outbound CERN-OHL-W license.”
Additional Discussions & Chat
Additional discussion focused on the question of Open Silicon.
Key Quotes: Our Goals
Best Practics: “What I’d like to see emerge is, okay, here are some pragmatic best practices that we can recommend to … other people who are beginning to design chips in this space”
FPGA Tool Chain Best Practics: “Maybe one of the things we put into our best practices from the Silicon Salon community is we want to use FPGA tool chains that meet certain criteria.”
Key Quotes: IP
IP Complexity: “I don’t think there’s any way to unravel that complexity. You have to steer clear of it.”
Stolen IP: “[W]e have encountered … companies whose chip designs contain so much stolen IP from other companies, but they won’t disclose what’s inside the chip because A, they don’t know, and B, they definitely don’t own it.”
Key Quotes: Open Source
Acceptance: “In the last 10 years a significant amount of open source technology has gone into proprietary products, commercial products. So there isn’t the resistance there used to be.”
Key Quotes: The Desire for Inspectability
A User Desire: “I just wanna say as a user rather than somebody trying to build hardware, probably the biggest benefit of open hardware me would be something like inspectability, right? Being able to see that a chip that I’m using isn’t bugged in some way.”
A Customer Desire: “We could actually take the design to a customer and say, ‘Go check it yourself.’ And there is a large marketplace that is interested in that.”
Key Quotes: The Challenges of Inspectability
Invisible Failures: “Even if I could visually inspect the chip, I suspect that you could have side channel failures that were happening at the gate level, really something that is completely invisible to somebody.”
Individual Tests vs. Mass Shipments: “There’s no way for us to easily prove that the thing we reviewed is the thing that we got.”
Corporate Obstacles: “If you try to do the same thing to Intel or to AMD, or even to Arm at a design level, you’ll find there’s a hundred lawyers in your way saying, no, you cannot see what’s inside the chip.”
Key Quotes: Formal Correctness Proofs
Proofs: “You can run formal correctness proofs to prove that the CPU correctly implements the specification.”
“You write the formal correctness proof once rather than having to run a hundred thousand unit tests where you’re never gonna catch the corner cases.”
Key Quotes: It’s Not Just about Cryptography!
The AI Threat: “You’re all probably aware that there’s an increasing debate about the safety of artificial intelligence. And one of the perspectives that my organization … is trying to bring to that debate is that none of the proposals these people are making make any sense unless we have real security at the hardware level, which we don’t right now.”
Thanks to our presenters and other participants!
- Host: Blockchain Commons
- Facilitators: Christopher Allen, Bryan Bishop
- Presenters: Andrew Poelstra, Cramium Labs, Red Semiconductor
- Sustaining Sponsors: Bitmark, Chia, CrossBar, Digital Contract Design, Foundation, Proxy, Unchained Capital
Chatham House Rules Apply
The Silicon Salon occured under the Chatham House Rules, meaning that information could be freely used by all participants and statements could be quoted, but not attributed. A goal of Blockchain Commons is to give principals in the Web3 and blockchain space the ability to discuss potential interoperability, but to do so in a safe way.
Silicon background image courtesy of Vecteezy.