Ethereum Foundation pivots away from Poseidon in post-quantum plan

If you have been building in the Ethereum ecosystem for a while, you know the drill. We find a shiny new cryptographic toy that promises to solve scalability, we hype it up, and then the underlying math changes so fast that the toy becomes a paperweight before it ever hits production. This week, it happened to Poseidon.

Justin Drake and the research team at the Ethereum Foundation recently signaled a major shift in the network's post-quantum strategy. They are moving away from the Poseidon hash function. For those not deep in the weeds of Zero-Knowledge (ZK) proofs, this might sound like a minor technical adjustment. It isn't. It represents a fundamental change in how we think about the trade-offs between speed and security.

The Lure of ZK-Efficiency

To understand why this matters, we have to look at why Poseidon was ever on the table. Standard hash functions like SHA-256 or Keccak (which Ethereum currently uses) are great for general security, but they are incredibly expensive to prove inside a ZK circuit. They require a lot of constraints, which means more computation, higher costs, and slower finality.

Poseidon was designed specifically to be ZK-friendly. It was built to minimize the number of operations needed to generate a proof. For a long time, the consensus was that if we wanted a post-quantum Ethereum that could handle high-throughput ZK-SNARKs, we had to use something like Poseidon. We were willing to trade off some of the battle-tested robustness of traditional hashes for the sheer performance gains of these new, specialized functions.

Why the Pivot is Happening Now

So, what changed? In simple terms: we got better at the math. According to Drake, recent advances in compact proofs have effectively erased the performance advantage that Poseidon held. We no longer need to rely on "ZK-optimized" hashes that haven't stood the test of time because our proving systems have become efficient enough to handle more traditional, robust structures.

This is a classic example of the software layer catching up to the protocol layer. We were trying to solve a performance problem by changing the ingredients of the recipe. Instead, we figured out how to build a faster oven. When the oven gets fast enough, you don't need to use the experimental ingredients that might leave a bad taste in your mouth five years down the line.

The Risk of New Cryptography

As a founder, I am always skeptical of "new" cryptography. In this industry, "new" is often a synonym for "untested." Cryptanalysis is a slow, grueling process of people trying to break things. Poseidon hasn't had the decades of scrutiny that something like Keccak or SHA-3 has enjoyed. By pivoting away from it, Ethereum is choosing the path of least resistance regarding long-term security.

If the Ethereum Foundation had stuck with Poseidon and a vulnerability was discovered three years from now, the migration path would have been a nightmare. Reverting a fundamental hash function at the protocol level is like trying to change the foundation of a skyscraper while people are still living in the penthouse. It’s expensive, dangerous, and usually results in a hard fork that splits the community.

What This Means for Builders

For those of you building ZK-apps or Layer 2 solutions, this is a signal to stop over-optimizing for specific hash functions that might not be around in the "endgame" version of Ethereum. We are seeing a trend where the Ethereum Foundation is prioritizing long-term stability over short-term performance hacks.

• Stick to the standards: If your project depends on Poseidon, it’s time to look at your technical debt. If the L1 is moving away from it, the tooling and support for it will eventually dry up.
• Focus on Prover Tech: The real gains are happening in the proving systems themselves (like GKR or other recent breakthroughs), not in the hash functions. Focus your engineering talent there.
• Quantum Readiness: Post-quantum security is no longer a "maybe" for the 2030s. The Foundation is actively re-architecting the roadmap to ensure that when quantum computers arrive, Ethereum doesn't just evaporate.

"The goal isn't just to be fast today; it's to be unhackable tomorrow. If we can get the same performance from proven math, why would we ever gamble on the new stuff?"

The Founder’s Perspective

I like this move. It’s uncharacteristically pragmatic for a research-heavy organization. Often, researchers want to push the absolute limit of what is theoretically possible, even if it adds layers of complexity that builders have to deal with. This pivot suggests that the Foundation is listening to the reality of the market: we need systems that work, that are safe, and that don't require us to rewrite our codebases every eighteen months.

The removal of Poseidon from the post-quantum plan is a sign that ZK technology is maturing. We are moving past the experimental phase where we had to make scary compromises just to get the thing to run. We are entering the optimization phase, where the standard tools are becoming good enough to support the dream of a scalable, private, and secure internet.

The Takeaway

Don't get married to the latest cryptographic flavor of the month. Ethereum’s pivot away from Poseidon shows that even the most promising "shortcuts" will be discarded if the underlying infrastructure becomes efficient enough to support the harder, safer path. Build for the long haul, use battle-tested primitives whenever possible, and keep a close eye on the research—but don't jump on every new hash function just because it has a cool name.

Read the original at Cointelegraph →