The main developer of Bitcoin Matt Corallo used the new announcement of Blockstream this week to return to the usual line in the quantum debate: that there is no serious person working for post-quantum cryptography of Bitcoin. The immediate trigger was Blockstream’s preview of OP_SHRINCSVERIFY, but the broader point is that the function didn’t just appear; it rests on research that has already been published and discussed publicly.
Bitcoin’s Post-Quantum Critics Are Wrong
Corallo’s post was blunt: “And the opponents of Bitcoin keep trying to say that no one is working on PQC in Bitcoin…” Blockstream, framed Jonas Nick’s upcoming talk at OPNEXT 2026 (April 16, 2026) about some technical artifact instead of a vague promise, saying, “He will be at NCSIFYSHRI.” It described the proposal as “a new opcode that enables SHRINCS,” an architecture aimed at post-quantum signatures with 324-byte state and static backups.
The event lineup itself also reinforces Corallo’s point. Quantum is not the only talk tied to Jonas Nick’s OP_SHRINCSVERIFY session. The main stage program includes Alex Pruden of Project 11 talking about “Quantum Bitcoin,” and later “Quantum / Investor fireside” featuring Robert Mitchnick of BlackRock and David Duong of Coinbase.
In other words, post-quantum risks and the response to them appear repeatedly on both the technological and institutional sides of the system.
The subtext was hard to miss: whatever one thinks about Bitcoin quantum moments, the claim that the problem is ignored is increasingly difficult to support.
What exactly are SHRINCS
Nick pitched SHRINCS in a December post on Delving Bitcoin as a hybrid hash signature design that combines a stateless scheme like SPHINCS+ with a robust scheme based on asymmetric XMSS. The design goal is to achieve the efficiency benefits of stateful signing when the state of the wallet does not change, while keeping a stateless return available if that state is lost or the backup must be restored.
In Nick’s words, the system “works best when fewer signatures are required” and “can be backed up with a static seed.” Bitcoin Optech later summed up the same trade-off very clearly: a cheap common-sense, heavy-duty back-and-forth signing where the integrity of the state is questionable.
That active claim is where the proposition is interesting for BTC. Nick wrote that the size of a SHRINCS signature for a standard route is min(292 + q·16, s_l) + 16, where q is the number of signatures that have already been generated in the best way. For q = 1, that yields a current 324-byte roundtable, which he said is more than 11x smaller than NIST’s standard minimum, ML-DSA, in that setting.
An earlier paper by Nick and Mikhail Kudinov made a broad case for hash-based signatures in Bitcoin, arguing that they are attractive post-quantum candidates because their security reduces hash guesswork, while keeping public keys small and the cost of verifying each byte within a usable range.
None of this is to say that Bitcoin suddenly has a resolved post-quantum roadmap. Nick’s Delving post clearly invited a response, and the December mailing list discussion raised unresolved questions about hardware performance, signature limits, wallet design, and whether Bitcoin should balance stateful and stateless schemes. Bitcoin Optech also covered SHRINCS as part of an ongoing discussion to change the consensus, not as an accepted development.
That’s why Corallo’s jab is important. A more accurate framework is not that BTC has solved post-quantum cryptography, but that engineering work is already underway in the public eye, with concrete proposals, concrete exchanges, and powerful opcodes attached to it.
In the debate that often fluctuates between complacency and panic, OP_SHRINCSVERIFY is proof of something fundamental: Bitcoin’s post-value discussion is no longer the subject of hand-raising, even if it is still a major research problem.
At press time, BTC traded at $66,630.
The featured image was created with DALL.E, a chart from TradingView.com
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