AmericanFortress Unveils Quantum Defense Plan for Satoshi-Era Bitcoin Holdings

Bitcoin relies on elliptic-curve cryptography to authenticate wallet transactions. A sufficiently powerful quantum computer could derive private keys from exposed public keys, allowing an attacker to forge signatures and seize funds. The risk is not immediate, but migration is complex because blockchains must distinguish legitimate owners from attackers after conventional signatures fail. Coinbase’s quantum advisory council said in June 2026 that about 7 million bitcoin could eventually be exposed if holders do not move assets to quantum-safe addresses.

On July 15, 2026, Project Eleven unveiled a post-quantum zero-knowledge proof developed with Jim Posen, lead maintainer of the open-source Binius proof system. The method uses BIP-32 wallet derivation to prove control of key material above an address without revealing it, potentially authorizing recovery into a quantum-safe wallet. On an M5 MacBook Air, the prototype generated a proof in 243 milliseconds using four cores and verified it in 40 milliseconds, with 2.1 GB of peak proving memory. It supports P2PKH, P2WPKH and P2SH-P2WPKH addresses, but remains unaudited and requires protocol-level integration.

Quantum computers could eventually undermine the public-key cryptography securing cryptocurrency wallets, exposing assets once the technology becomes powerful enough. Blockchain security company AmericanFortress is proposing a quantum-resistant approach for Bitcoin, Ethereum and Solana users. The plan is significant because it seeks to strengthen existing wallets without forcing holders to adopt new addresses, a process that can create operational friction, transaction costs and additional security risks.

AmericanFortress’s proposed system uses a wallet’s seed phrase to generate a zero-knowledge proof, allowing users to demonstrate control and activate quantum-safe protection without moving funds. The approach is designed to avoid address replacement and asset migration across the three named blockchain ecosystems. Available information does not specify a formal launch date, pricing, audited performance figures or a timetable for production deployment.

If quantum computers were to break Bitcoin's ECDSA signatures, funds held at older addresses whose public keys have been exposed could be stolen. These include addresses attributed to Satoshi Nakamoto, who is estimated to hold about 1.1 million BTC. The dispute centers on whether the community should preemptively freeze vulnerable legacy coins: doing so could prevent theft but might also permanently deprive their original owners of access.

Paradigm partner Dan Robinson unveiled PACTs on May 1, 2026. The proposal would let holders use BIP-322 signatures and OpenTimestamps to create private, timestamped proof of control without moving their BTC. If Bitcoin later freezes vulnerable addresses through a soft fork, holders could recover their assets using quantum-resistant STARK proofs. The proof must be created before a quantum attack or freeze, however, and the proposal has not yet been implemented.

Bitcoin transactions rely on elliptic-curve digital signatures. A sufficiently powerful quantum computer running Shor’s algorithm could derive private keys from exposed public keys and steal assets. Replacing the signature mechanism would require network-wide consensus and asset migration, drawing attention to StarkWare’s upgrade-free approach as a fallback until longer-term changes such as BIP-360 are completed.

On April 9, 2026, StarkWare Chief Product Officer and BIP-360 co-author Avihu Levy published the QSB paper and open-source code. The system uses Bitcoin’s existing Script constraints and hash-based proofs to create quantum-resistant transactions without a soft fork or miner activation. Each transaction requires substantial offline GPU computation at an estimated cost of $75–$200, and the tool is currently intended for emergency recovery.