The Vault Introduces In‑House MPC Library for Institutional Custody

Barcelona, 17 September 2026 – The Vault, an institutional digital‑asset custody platform regulated in Switzerland and the EU, announced the launch of its proprietary multi‑party computation (MPC) library. The library enables separate parties to hold shares of a signing key, ensuring that a complete private key never resides on any single device or server.

Independent Security Audit Completed

The release follows a security audit by blockchain‑security firm Halborn. The audit covered 91 files across the cryptographic core, test suite, and mobile signer applications for iOS and Android. All findings were remediated and verified by August 2026.

Sovereign Cryptography Approach

Unlike most custody providers that license external MPC components, The Vault built the library in‑house. This “sovereign cryptography” model gives the platform control over the code, signing protocol, and release schedule, allowing security fixes to be shipped on its own timetable and enabling full code review by auditors.

Technical Highlights

• Implements distributed key generation, resharing, refresh, recovery, and threshold ECDSA/EdDSA signing.
• Includes commitment, oblivious transfer, zero‑knowledge proof primitives, and transport for protocol messages.
• Written in Rust, providing memory safety without a garbage collector.
• Single codebase runs on The Vault’s servers and on mobile signers for iOS and Android.

Co‑Signing Model for Clients

In The Vault’s co‑signing model, the client retains a key share on their own device, while the mobile signer application accesses that share for transaction authorization. The MPC library is offered as an add‑on to The Vault’s SaaS custody product.

Future Plans

The Vault intends to open‑source the Rust library, allowing broader examination of its cryptography. The team is also developing two new protocols: a threshold variant of the post‑quantum ML‑DSA signature scheme and a threshold post‑quantum password‑authenticated key exchange (PAKE).

Industry Perspective

Halborn’s SVP of Security, Gabi Urrutia, highlighted that proprietary cryptography gives custody providers direct control over security updates and enables auditors to review the complete implementation, a critical factor for institutional due diligence.