StarkWare Demonstrates Quantum-Safe Bitcoin Transaction on Mainnet in Research Demonstration
StarkWare's QSB (Quantum Safe Bitcoin) transaction, a research demonstration by researcher Avihu Levy, was confirmed in block 964,199 on Aug. 26, 2026. It uses Bitcoin's existing legacy scripting rules with no soft fork, but ordinary nodes won't relay it and it does not make ordinary BTC holdings quantum-safe. The work builds on Starknet's August 7, 2026 quantum-resistant signature validation.
Tel Aviv. StarkWare's QSB (Quantum Safe Bitcoin) transaction was a research demonstration by researcher Avihu Levy, not a production-level milestone. StarkWare announced the transaction on Aug. 26, 2026. It was confirmed in block 964,199 on that date. It uses Bitcoin's existing legacy scripting rules and needs no soft fork. Ordinary nodes won't relay it, so it takes a miner willing to accept out-of-band submissions. It does not make ordinary BTC holdings quantum-safe. The achievement builds on Starknet's August 7, 2026 quantum-resistant signature validation.
The transaction addresses a structural vulnerability in blockchain cryptography. Bitcoin and all major blockchain protocols rely on elliptic curve digital signature algorithms (ECDSA/EdDSA), which are susceptible to Shor's algorithm once cryptographically relevant quantum computers emerge. NIST's Post-Quantum Cryptography Project and industry consensus place that threat window at 10 to 15 years. With Bitcoin's market capitalization estimated at $1.2 to $1.5 trillion as of August 2026, the stakes for delayed migration are significant.
StarkWare's implementation leverages Starknet's Cairo language and STARK proof system, both of which support post-quantum cryptographic schemes by design. The quantum-safe Bitcoin transaction validates cross-chain interoperability between Starknet's Layer 2 environment and Bitcoin's base layer, establishing a pathway for post-quantum asset migration without requiring immediate changes to Bitcoin's base layer consensus rules. Starknet currently holds an estimated $2.8 to $3.2 billion in total value locked, with daily transaction volume ranging from $400 to $600 million.
The announcement coincides with broader institutional activity in blockchain infrastructure. Citigroup announced Bitcoin custody services in August 2026, bringing $2.3 trillion in assets under administration into the digital asset custody market. The stablecoin market, led by Tether's USDT at approximately 59% of a $305 billion market as of September 2026, represents additional settlement infrastructure that will require post-quantum security standards as adoption matures.
Among Layer 2 protocols, Starknet is the first to have deployed quantum-resistant infrastructure at the production level. Arbitrum, the largest Layer 2 by total value locked at an estimated $4 to $5 billion, has no announced post-quantum cryptography roadmap. Optimism similarly remains dependent on Ethereum's base layer security timeline. Bitcoin-native Layer 2 solutions, including Stacks and Merlin, have not demonstrated comparable quantum-safe capabilities on mainnet.
The development has implications beyond Starknet's ecosystem. Bitcoin Core developers are expected to begin formal evaluation of quantum-safe proposals in coming quarters. Major custodians including Coinbase, Kraken, and Fidelity face increasing pressure to articulate post-quantum custody roadmaps as institutional clients formalize security requirements. NIST's post-quantum cryptography standardization process is expected to produce final adoption timelines in 2026 and 2027.
Key limitations apply. The QSB transaction is a research demonstration and does not make ordinary BTC holdings quantum-safe. Bitcoin's base layer adoption of post-quantum standards requires broad community consensus and a hard fork process with uncertain outcomes. Layer 2 quantum-safe implementations protect assets transacted through Starknet's infrastructure but do not directly secure Bitcoin held in native base layer addresses. Post-quantum cryptographic standards, including NIST-approved schemes, may contain undiscovered vulnerabilities. StarkWare has indicated it is implementing multiple post-quantum algorithms and maintaining cryptographic agility to address this risk.
About StarkWare
StarkWare Industries is a blockchain infrastructure company headquartered in Tel Aviv, Israel. The company develops Starknet, a permissionless Layer 2 network built on Ethereum using STARK proof technology, and StarkEx, a scalability engine deployed by major trading platforms. StarkWare's Cairo programming language and STARK-based validity proof system provide the cryptographic foundation for its post-quantum security implementations. Founded in 2018, StarkWare has raised over $270 million from investors including Sequoia Capital, Paradigm, and Tiger Global.
Media Contact: [email protected] Technical Documentation: starknet.io/quantum-safe StarkWare: starkware.co