Blockstream and Thales launch Bitcoin custody system built around offline signing

Blockstream has rolled out a new institutional custody system for Bitcoin. Its core idea is pleasantly old-fashioned: keep the keys away from the internet.

The product was built with French technology group Thales and announced on Friday, November 13, 2026. It pairs Thales hardware security modules with Blockstream’s own Secure Multi-Party Computation technology. The pitch is that institutions can approve transactions while sensitive key material stays sealed inside dedicated hardware.

The timing is deliberate. Blockstream co-founder Adam Back has been arguing for simpler, offline security models, especially as AI-assisted cyberattacks become a bigger worry for anyone holding Bitcoin at scale.

How the system works

Secure Multi-Party Computation, which Blockstream brands as Secure-MPC, adds another layer. Instead of a single private key, the signing authority is split into shares. Several parties then work together to produce a valid signature, and no single share is enough to move funds.

The notable design choice is where the signing happens. Blockstream says the entire transaction signing protocol runs inside the Thales HSMs. That means private keys and MPC key shares never cross the hardware boundary during signing.

The system is aimed at custodial banks, prime brokers and other institutional users. Features include policy controls, segregated accounts, multisignature options and cryptographic audit trails.

Blockstream Enterprise supports several signing models, including air-gapped setups and multisignature systems.

Part of a broader enterprise push

The custody launch did not arrive alone. Blockstream’s Enterprise custody and tokenization services are in beta with select private clients. That beta opened in Q3 2026.

The company walked through the full security architecture at the Digital Assets Forum in New York on the same day as the announcement.

Blockstream was co-founded by Back in 2014. The company has long focused on Bitcoin-native infrastructure rather than chasing other chains.

Its best-known enterprise product is the Liquid Network, a Bitcoin sidechain built for faster settlement and issuing digital assets. Liquid recently passed more than $3 billion in total value locked, a measure of the assets held on the network.

The company has also been growing its footprint, with a new office opened in Lugano in late 2026.

Why simpler security is the selling point

Back’s argument cuts against a common industry instinct. His case is that fewer moving parts mean fewer openings. Keeping the most sensitive operations offline, inside purpose-built hardware, removes whole categories of remote attack.

The AI angle gives that argument new urgency. If attackers can use AI tools to find vulnerabilities faster, scan code at scale, or craft more convincing phishing, then software-heavy security gets harder to defend. Hardware isolation does not care how clever a phishing email is.

What this means for institutions and the custody market

For institutions, the question is less about Bitcoin’s price and more about operational risk. Banks and prime brokers that hold Bitcoin for clients need to show regulators and auditors exactly how keys are protected. A system where keys never leave certified hardware, with audit trails built in, speaks that language directly.

Blockstream’s research materials frame the launch as a way to build trust with institutional investors who may have hesitated over security concerns.

The pairing with tokenization services is also worth watching. Combined with Liquid’s existing asset issuance tools, Blockstream is assembling a stack where an institution could custody Bitcoin and issue tokenized assets through a single provider.