Crypto infrastructure firm AmericanFortress has published a technical paper detailing a post-quantum security scheme designed to safeguard existing Bitcoin, Ethereum, and Solana wallet addresses against quantum computing attacks—without forcing users to rotate their keys, alter their address formats, or move their assets.
Published on the International Association for Cryptologic Research (IACR) ePrint archive, the proposal introduces a cryptographic framework known as Zero-Knowledge Proof of Seed Provenance (ZK-PoSP). The design seeks to solve one of the most stubborn dilemmas in post-quantum blockchain engineering: how to protect hundreds of billions of dollars in digital assets from future quantum decryption without triggering massive user confusion, network congestion, or unintended asset loss.
By swapping out conventional elliptic curve signature authorization for non-interactive zero-knowledge proofs (NIZKs) derived from a wallet’s seed phrase, AmericanFortress claims networks can maintain their existing address ecosystems intact while rendering transaction authorization quantum-resistant.
The Threat: $470 Billion in Quantum-Exposed Digital Assets
While cryptographically relevant quantum computers (CRQCs) capable of executing Shor’s algorithm remain years away, the mathematical vulnerability of classical public-key cryptography is a pressing concern for long-term blockchain stability.
Networks like Bitcoin and Ethereum rely on the secp256k1 elliptic curve signature scheme, while Solana uses Ed25519. Under these systems, if an address’s public key is exposed on-chain—which occurs whenever a transaction is sent from a Pay-to-Public-Key-Hash (P2PKH) address, or inherently exists on Pay-to-Public-Key (P2PK) legacy outputs—a sufficiently powerful quantum computer could derive the corresponding private key and drain the funds.
Recent estimates highlight the scale of this vulnerability. A market report by Galaxy and Project Eleven estimated that roughly 7 million BTC—worth roughly $470 billion at current valuations—resides in addresses whose public keys are already visible on the public ledger. This includes dormant coins from Bitcoin’s earliest years, such as Satoshi Nakamoto’s estimated 1.1 million BTC holdings, as well as active wallets that have reused addresses or executed outgoing transfers.
Standard post-quantum migration proposals typically require replacing elliptic curve signatures with lattice-based or hash-based digital signature algorithms, such as Dilithium or SPHINCS+. However, these schemes demand much larger key sizes and signature payloads. More importantly, they require every token holder to manually generate a new quantum-resistant wallet address and transfer their funds over—a process that poses massive operational challenges for institutional custodians, ETF issuers, and everyday users.
How ZK-PoSP and QBIP32 Preserve Existing Wallets
AmericanFortress’s ZK-PoSP scheme bypasses the need for address migration by changing how transactions are authorized rather than changing the address structure itself.
Hierarchical Deterministic (HD) wallets—governed by standards like BIP32, BIP44, and SLIP-10—derive an arbitrary number of keypairs from a single master seed phrase. Under ZK-PoSP, instead of publishing an ECDSA signature that exposes the public key to potential quantum recovery, the spending wallet generates a zero-knowledge proof proving to the network that it possesses the seed phrase used to derive that specific address.
To facilitate this derivation smoothly, AmericanFortress also introduced an algorithm called QBIP32. In a single function call, QBIP32 generates a signing scalar, a post-quantum witness, and an updated chain code. According to the research team, QBIP32 can be applied across prime-order elliptic curves, making it compatible with both secp256k1 (Bitcoin and Ethereum) and Ed25519 (Solana).
Because the zero-knowledge proof validates ownership without leaking the seed phrase or the underlying classical private key, a quantum computer observing the transaction cannot reverse-engineer the authorization mechanism to steal funds.
“The goal is to preserve the user’s existing identity and setup,” AmericanFortress stated in its release. “Holders continue using their existing wallets and seed phrases, while the underlying verification layer transitions to zero-knowledge proofs.”
Benchmarks and Performance Overhead
To demonstrate practical feasibility, AmericanFortress implemented the ZK-PoSP framework in Rust using the RISC Zero zero-knowledge virtual machine (zkVM).
According to computational test results cited in the paper:
- Proof Generation Time: Generating a one-time transaction proof on a standard 16-core server takes approximately 12 to 13 seconds.
- On-Chain Verification Time: Validating the proof at the node level takes between 9 and 10 milliseconds.
- Estimated Computational Cost: Generating an initial setup proof for an address costs roughly $0.002, while subsequent transaction proof generation averages $0.00125.
While 12 seconds for client-side proof generation is noticeably slower than traditional instant ECDSA signing, proponents argue it is an acceptable trade-off for high-value transactions or cold-storage protection against quantum adversaries.
The Obstacles
Despite its technical promise, AmericanFortress’s proposal faces significant hurdles before it could safeguard live assets on Bitcoin, Ethereum, or Solana.
First, the scheme requires consensus-level network upgrades. For ZK-PoSP to work, participating blockchain nodes must be updated to accept and verify NIZK proofs alongside or in place of classical signatures. On decentralized networks like Bitcoin, introducing new authorization schemes requires broad community consensus, rigorous auditing, and a formal soft-fork or hard-fork proposal. Until a network natively supports these proof verifiers, wallets with exposed public keys remain vulnerable to potential quantum attacks.
Second, the post-quantum security of ZK-PoSP is currently framed as “conjectured.” Because the proposal relies on the quantum hardness of specific hash functions and recursive NIZK proof systems, it has not yet undergone full peer review or testing against cryptographically relevant hardware.
Third, commercial distribution may influence adoption. AmericanFortress intends to license its software development kit (SDK) to wallet providers and layer-1 networks, meaning adoption will depend as much on economic terms and developer integration as on academic validation.
A Broader Push for Quantum Readiness
The proposal arrives amid a broader surge in post-quantum research across the cryptocurrency sector.
In late July, major industry players—including BlackRock, Coinbase, Strategy, Fidelity Digital Assets, Anchorage Digital, Galaxy, and Blockstream—launched the Bitcoin Security Consortium, pledging $15 million over three years to fund research into post-quantum defenses for major networks.
Concurrently, hardware manufacturers are exploring alternative approaches. Hardware wallet maker Freedom Factory recently unveiled the PQ1, an EVM-compatible hardware wallet that utilizes SPHINCS+ signatures and ERC-4337 account abstraction to achieve quantum resistance at the hardware level.
As the timeline for quantum computing advances, the debate over how to protect decentralized ledgers is moving from academic theory to concrete software engineering. Proposals like ZK-PoSP highlight a growing industry consensus: for post-quantum defense to achieve widespread adoption, it must protect user assets without breaking the core user experience.