BTQ Technologies has launched a Bitcoin Quantum testnet to trial post-quantum signatures, focusing on public key exposure and signature security. The testnet replaces ECDSA with ML-DSA, significantly increasing transaction size and block space demands. The risk of key exposure is a key concern, with potential long-range and short-range vulnerabilities.

The testnet explores post-quantum signatures in a Bitcoin-like environment, using ML-DSA as a replacement for ECDSA. With public key exposure being a critical factor in quantum risk models, the testnet aims to study the behavior of quantum-resistant signatures in a practical setting. BTQ Technologies is a research-focused firm specializing in post-quantum cryptography and blockchain security.

Most discussions around Bitcoin quantum risk center on digital signatures and the threat of Shor’s algorithm. The concern is that a sufficiently capable quantum computer could derive private keys from exposed public keys, potentially enabling unauthorized spending. BTQ’s testnet makes engineering trade-offs to accommodate larger signatures and study the impact on block size and transaction data.

“Old BTC risk” refers to legacy output types and address reuse patterns that expose public keys onchain, making them vulnerable to quantum threats. Some output types, like P2PK, P2MS, and P2TR, are more susceptible due to direct public key exposure in the locking script. Address reuse can also extend the exposure window for public keys, increasing the risk.

Bitcoin’s response to quantum threats involves sequenced mitigation strategies, such as exploring new output types like P2TSH to reduce structural exposure within existing script designs. These proposals aim to avoid quantum-vulnerable key spends while maintaining compatibility and addressing the trade-offs associated with post-quantum signatures. Bitcoin’s preparedness for quantum threats is an ongoing debate within the development community.

BTQ’s Bitcoin Quantum testnet serves as a valuable sandbox for measuring the costs and constraints of post-quantum signatures in a Bitcoin-like system. While the testnet highlights the engineering challenges and trade-offs involved in implementing quantum-resistant signatures, it does not imply that Bitcoin is imminently breakable. The testnet provides insight into the practical considerations of transitioning to post-quantum cryptography in the future.

Read more at Cointelegraph: BTQ’s Bitcoin Quantum Testnet and “Old BTC” Risk, Explained