Anchorage Digital Details Post-Quantum Security for Crypto Assets

Anchorage Digital, a federally chartered crypto bank, has published a technical strategy for migrating institutional digital asset custody to post-quantum cryptography. The company's plan addresses the risk that future fault-tolerant quantum computers could break widely used public-key cryptographic schemes, exposing dormant or in-transit digital assets to retrospective decryption attacks. The strategy is designed to mitigate so-called "harvest now, decrypt later" threats, in which adversaries collect encrypted data today in anticipation of future quantum decryption capabilities.

Cryptographic Safeguards

The Anchorage Digital approach integrates three main cryptographic measures. First, the firm has adopted hash-based Bitcoin address conventions that prevent public key exposure until a transaction is executed, reducing the risk that dormant Bitcoin holdings could be compromised by quantum attacks targeting exposed public keys. Second, the company has implemented hybrid post-quantum key encapsulation within its internal transport layer security (TLS) systems, including managed ChromeOS devices, to protect data in transit from interception and future decryption. Third, Anchorage Digital has upgraded its hardware security module (HSM) architecture to support post-quantum signature algorithms, allowing for firmware updates to accommodate new NIST-standardized schemes without requiring a full system overhaul.

Migration Protocols and Research

In parallel with infrastructure changes, Anchorage Digital has released original cryptographic research to address the challenge of migrating existing blockchain assets to post-quantum security. The company introduced the Post-Quantum Turnstile, a zero-knowledge protocol based on STARKs (scalable transparent arguments of knowledge), which enables holders of legacy credentials-estimated to cover roughly two-thirds of circulating Bitcoin-to transfer signing authority to post-quantum keys without revealing private or public key material. This approach is intended to facilitate a large-scale migration without exposing sensitive information on-chain.

Open-Source Implementations and Signature Schemes

Anchorage Digital has also open-sourced sqisign-rs, a Rust implementation of the SQIsign signature scheme, which is based on supersingular elliptic curve isogenies. SQIsign offers a compact signature size, with the company reporting that its on-chain footprint is approximately seven times smaller than Falcon, another post-quantum candidate. The open-source release is intended to support broader adoption and independent evaluation of post-quantum signature schemes for blockchain applications.

Industry Context and Remaining Challenges

While Anchorage Digital's roadmap focuses on institutional custody, the broader migration to post-quantum cryptography across public blockchains remains a complex engineering and governance challenge. Many existing blockchain protocols were not designed for cryptographic agility, and large-scale migration will require coordination among developers, custodians, and users. The technical and operational hurdles are significant, and the timeline for practical quantum attacks remains uncertain. For context, other quantum infrastructure projects, such as the deployment of quantum networks for secure communication, are also advancing, as seen in the recent integration of trapped-ion quantum computers with photonic networking for research and workforce development.

Post-quantum cryptography refers to cryptographic algorithms designed to resist attacks from both classical and quantum computers. Unlike quantum key distribution, which relies on quantum physics for security, post-quantum algorithms run on conventional hardware and are intended as drop-in replacements for current public-key schemes. The transition to post-quantum standards is being coordinated by organizations such as NIST, but secure deployment requires careful implementation, side-channel resistance, and broad ecosystem support. The migration of blockchain assets to post-quantum security is especially challenging because public keys may already be exposed on-chain, and not all users can easily rotate credentials. As a result, technical solutions must address both cryptographic soundness and practical migration pathways.