- Tezos introduced TzEL, an experimental privacy rollup using zk-STARK proofs and post-quantum cryptography on its testnet.
- TzEL addresses the “harvest now, decrypt later” problem: encrypted data stored today could be decrypted once quantum computing matures.
- The project uses Tezos’ data availability layer and rollup architecture to handle proofs of up to 300KB per transaction.
Tezos launched TzEL, an experimental privacy rollup deployed on its testnet that stands as one of the first attempts to design private transactions built to resist attacks from quantum computing. The project combines zk-STARK proofs with post-quantum cryptography, deliberately moving away from elliptic curve cryptography that dominates most of the crypto industry today.
The core problem TzEL seeks to address is not present-day privacy, but the privacy of the future. Ordinary blockchain transactions are public by design, but privacy systems introduce layers of encryption to conceal amounts, recipients and sensitive metadata. That encryption works well today, but on-chain data is permanent. Someone could collect encrypted information now and retain it until a sufficiently powerful quantum computer becomes capable of breaking the cryptography protecting it — an attack vector known as “harvest now, decrypt later“.
Tezos Puts TzEL to Work on the Testnet
The system allows users to shield tez within the rollup, transfer them privately between participants and unshield them back to the base layer. It also incorporates encrypted memos, viewing keys, detecting keys and delegated proving — tools oriented toward selective disclosure: transactions are private by default, but the user can reveal specific information when required.
What distinguishes TzEL from a purely theoretical exercise is that it already includes a functional rollup stack, wallets, bridge flows, proving infrastructure and accessible tools for developers directly on the testnet.
The size of zk-STARK proofs is one of the most significant technical challenges to resolve: each transaction can reach 300KB, a volume that would be costly or outright unviable to process repeatedly on the base layer of many networks. TzEL addresses this through Tezos’ data availability layer, known as DAL, and its rollup architecture — infrastructure designed to handle significantly larger data volumes with greater efficiency.
This product turns features typically described in abstract terms — scalability, modularity, data availability — into something tangible and measurable. TzEL is still experimental code, not suitable for transactions involving real value, but it demonstrates in practice what the infrastructure Tezos has built over recent years is actually for.