Blockstream Launches Institutional Bitcoin Custody System Using MPC Protocol Inside Thales Modules
Key Facts
Blockstream announced the launch of an institutional digital asset custody solution developed with Thales, running the Secure-MPC multi-party signing protocol entirely inside the hardware security modules supplied by the French company. Blockstream says the system performs signing inside those modules rather than moving their security components to another environment. The company described the solution as designed for institutions, as part of its digital asset management services. In its product description, it said: "The Secure-MPC protocol runs entirely inside Thales hardware security modules." The partnership places Thales’ security hardware at the center of the signing architecture developed by Blockstream.
The security architecture centers on keeping private keys and MPC key shares within the security boundaries of HSMs. Blockstream said these elements "never leave the security boundaries of the HSMs," defining where the access components needed for signing are held while the protocol runs. The system therefore relies on carrying out signing within the security hardware environment itself. This mechanism supports the product’s positioning for institutions that manage digital assets and need an operational custody infrastructure. In its official description, the company does not claim that the solution replaces traditional multisignature signing or that it has vulnerabilities; instead, it presents the Secure-MPC mechanism and its relationship with Thales security modules.
Blockstream offers three deployment models, ranging from a managed service to full operation at the client’s premises. The first model is called TIER 1 and is a managed service; TIER 2 provides a dedicated deployment using a client-owned HSM. TIER 3 allows the system to run at the institution’s premises. According to the product description, these options give clients different degrees of hosting, customization and operational control. The company links these models to its institutional custody service, without specifying pricing differences or commercial terms for each tier in the published materials.
Transaction controls include K-of-N threshold approvals, with duties separated among preparer, approver and authorizer roles. According to Blockstream, spending limits are checked against directly signed price data, while withdrawals are restricted to approved destinations. These rules add procedural layers to key custody and signing by distributing approvals and checking spending limits and transfer destinations. The company describes these as transaction governance features included alongside the product’s MPC and HSM-based architecture. The available materials did not provide figures for spending limits or the number of approvers required for each transaction.
Blockstream positions the solution within a digital asset management suite targeting banks, prime brokers and companies already operating in bitcoin. According to the company’s third-quarter 2026 update, the suite includes a custody and transfer layer that enables these groups to manage digital assets. This positioning reflects the product’s move toward institutional needs beyond key storage, with the suite combining custody and digital asset management. In a U.S. regulatory context, the Securities and Exchange Commission proposed updated rules on crypto asset custody by investment advisers and funds on 1 October 2026, setting 7 December 2026 as the deadline for comments. SEC Chair Paul Atkins said the proposal seeks to "close a gap that has left investment advisers and funds uncertain about how to legally custody an asset class their clients increasingly demand."
Blockstream had said the security model for institutional custody would be unveiled at the Digital Asset Forum in New York on 13 November 2026. The company’s update indicated that the MPC unveiling would be part of the event, alongside development of signing solutions fully isolated from internet connectivity. This places work on offline signing solutions within the company’s broader institutional custody efforts, without specifying a launch date. Thales shares, listed under the ticker THLLY, closed at 50 dollars in the 12 November 2026 session, according to EL7 data. That figure is for a session before the announced unveiling, not the 13 November session.