Tezos Tests Post-Quantum Privacy as Founder Slams ‘Half-Baked’ Bitcoin Quantum Theories

While practical quantum computers capable of breaking modern cryptography do not yet exist, Tezos co-founder Arthur Breitman said some pockets of the crypto industry are treating quantum computing like a conspiracy theory while ignoring a legitimate threat to blockchain privacy.

The warning comes as Tezos launches TzEL, a post-quantum privacy system on testnet designed to protect private payments and encrypted transaction data from future “harvest now, decrypt later” attacks. Breitman said Tezos is acting with “a sense of urgency,” while parts of the industry remain complacent about quantum threats in his view.

“Some projects are barely maintained and won’t be upgraded at all; but the important ones will be upgraded, mostly in a timely fashion,” Breitman told Decrypt.

Breitman took particular issue with some in the Bitcoin community promoting what he described as pseudo-scientific theories about quantum computing.

“There are Bitcoiners being applauded on stages for half-baked crank theories about quantum mechanics that fly in the face of established physics,” he said.

The cultural debate centers on whether blockchain networks should begin preparing now for a future where quantum computers could break the elliptic curve cryptography widely used across crypto today.

The concern is especially acute because blockchain data is permanent. By design, transactions and other data are stored publicly on-chain indefinitely, creating the potential for what security researchers call a “harvest now, decrypt later” attack.

In such a scenario, attackers collect blockchain data in the form of public keys and store them until quantum computers become powerful enough to break the cryptography protecting them, thus exposing private keys and allowing for funds to be stolen.

One challenge facing post-quantum privacy systems, however, is scale. Quantum-resistant zk-STARK proofs are substantially larger than the proofs used in many existing blockchain privacy tools, creating storage and throughput problems. Breitman said that Tezos is equipped to handle that challenge.

“Post-quantum shielded transactions can take up a lot of space,” he said. “Tezos has a functioning data availability layer that can absorb them without increasing the load for consensus nodes.”

The project remains experimental, and Breitman said several steps still need to happen before broader deployment. He added that Tezos has also started introducing post-quantum signature support for user accounts as part of a broader effort to prepare the network for future threats.

“The fact the encrypted memo can be decrypted in the future means there is value in switching early,” Breitman said. “Work to make the entirety of Tezos post-quantum is active and ongoing.”

Breitman argued the industry still has time to prepare for quantum threats, but warned that developers are underestimating how quickly that window could close. His comments also come as recent reports from quantum security firm Project Eleven warned that “Q-Day,” the point at which quantum computers become capable of breaking modern cryptography, could arrive as early as 2030.

“The main risk is complacency among developers,” he said. “Elliptic curve signatures won’t be broken in a few months, but there’s a good chance they’ll be broken in a few years. That leaves enough time to upgrade, but not enough to quibble.”