I've been thinking about the verification problem in SETI for a while now, and I ended up building something that I think this community might find interesting (or tear apart — either works).
The basic idea: instead of waiting for signals and arguing about whether they're real, what if we created a publicly verifiable test that only something with beyond-human computational capabilities could pass?
How it works
The protocol pulls a SHA-256 hash from a confirmed Bitcoin transaction — so the hash is anchored to a real, timestamped event on an immutable public ledger. Nobody can predict it or pre-compute it. A claimant gets 5 minutes to provide the preimage (the original input that produces that hash).
Here's why that matters: SHA-256 has a property called preimage resistance. The search space is 2256. If you ran every NVIDIA H100 GPU ever manufactured simultaneously, brute-forcing a single preimage would take roughly 2.3 × 1035 years. The universe is ~1.4 × 1010 years old. We're talking 1025 times the age of the universe. It's not a soft barrier — it's a wall.
Why I think this is relevant to SETI
Most of our SETI methodology is about detection — listening for signals, scanning for technosignatures. But we don't have a great framework for verification if something actually showed up and said "hey." How would we know it's real and not a hoax?
This protocol doesn't solve the detection problem, but it creates a zero-trust verification layer. No shared secrets, no pre-established communication channels, no central authority deciding what counts. Just math that either checks out or doesn't.
If something passed the challenge, there are really only three explanations:
- SHA-256 was broken (which would be historic on its own — it secures Bitcoin, TLS, basically the entire internet)
- Quantum computing made a leap nobody saw coming (Grover's algorithm only gets you to 2128, still absurdly large)
- Something we don't have a framework for — computational capabilities so far beyond ours that reversing SHA-256 is trivial
What I'm looking for
I genuinely want criticism. Edge cases I haven't thought of. Assumptions that don't hold. Ways the protocol could be gamed that I'm missing. I wrote a more formal paper on it if anyone wants the technical details — it's on Zenodo with a DOI: https://doi.org/10.5281/zenodo.19153514
The live protocol is at thealienchallenge.com if you want to see it in action (you won't solve it — that's the point).
I know this sits in a weird space between cryptography and SETI, and I'm not claiming it's going to change anything overnight. But I do think the verification question deserves more serious thought than it gets, and this is my attempt at contributing something concrete to that conversation.
Curious what you all think.
