“It turns out you can transform this problem into just a big matrix vector multiplication. And it turns out that our friends in the AI world have made big matrix vector multiplications very cheap and usable for us. Go have someone buy an H100 and go service for all of us. So these two things have come together: the cryptography side invented this, and AI land has really optimized GPUs to make this a viable world.”
Bankless · Crypto & Web3 · November 2026
Context
Ojha was explaining private information retrieval, which lets a Zcash wallet ask a server for its payments without the server learning anything. His point is that GPU hardware built for AI is what makes the technique practical.
Transcript
…server won't learn anything. This should feel a bit like FHE. Somehow, I can encrypt some data, go talk to a server, or the server does some stuff on the data, gives you back an answer, and the answer is useful for me. And it should feel like FHE because it literally uses homework under the hood.
Because it is SHE.
Yeah. So it turns out for this precise use case, there were breakthroughs and tricks that makes it very fast to do on a server. It turns out you can transform this problem into just a big matrix vector multiplication. And it turns out that, hey, our friends in the AI world have made big matrix vector multiplications very cheap and usable for us. Go have someone buy an H100 and go service for all of us. So these two things have come together. The cryptography side invented this. And like AI Land has really optimized GPUs to make this a viable world. And so that's where we're going with the wallet side to make that scale.
And Zcash has already deployed this PIR stuff. We just had a coin holder vote where we used it for the first time, I think, in any cryptocurrency projects has ever used PIR. We used it less than a couple of months ago.
How does this not introduce a centralized third party? However, if we are queering a server, okay, I get that with FHE and the advancements in GPUs and processing power and all of that stuff, that I will be able to remain anonymous because that's what the math does. It keeps me anonymous. But…
So there's two parts. One is kind of like RPCs, where take Ethereum, right? You have to go talk to one RPC provider. Now, it's permissionless to go make a new RPC provider. Just go download a new copy of the chain and go index it yourself. And there's multiple providers already there. There's…
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