Institutional Vault uses Blockdaemon’s Advanced MPC Threshold Security Module (TSM) to perform **threshold signing**. Private keys are split across multiple independent policy nodes and are **never reconstructed** on a single machine. Blockdaemon MPC solutions are based on public research (some of which was performed by the Blockdaemon team), this includes protocols from the following research papers:

- **[MRZ15]** Payman Mohassel, Mike Rosulek, Ye Zhang: _Fast and Secure Three-party Computation: The Garbled Circuit Approach_. CCS 2015.
- **[WRK17]** Xiao Wang, Samuel Ranellucci, Jonathan Katz: _Authenticated Garbling and Efficient Maliciously Secure Two-Party Computation_. CCS 2017.
- **[DJNP+18]** Ivan Damgård, Thomas Pelle Jakobsen, Jesper Buus Nielsen, Jakob Illeborg Pagter, Michael Bæksvang Østergård: _Fast Threshold ECDSA with Honest Majority_. SCN 2020.
- **[DKLs19]** Jack Doerner, Yashvanth Kondi, Eysa Lee, Abhishek Shelat: _Threshold ECDSA from ECDSA Assumptions: The Multiparty Case_. IEEE S&P 2019.
- **[DKLs23]** Jack Doerner, Yashvanth Kondi, Eysa Lee, Abhishek Shelat: _Threshold ECDSA in Three Rounds_. IEEE S&P 2024.

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## MPC signing operations

| Operation | Curve / parameters | MPC protocol | Typical use |
| --- | --- | --- | --- |
| **ECDSA** | **secp256k1** | **DKLs23** | EVM networks, Bitcoin-style signing |
| **EdDSA** | **Edwards25519** | **SCHNORR** | Ed25519-based chains and system signatures |

### Round Complexity ECDSA (ECDSA secp256k1)

This setup implies seven rounds for ECDSA:

- One round for exchanging metadata.
- Three rounds for generating OTs.
- Three rounds for the actual MPC signing protocol.

### Round Complexity Schnorr (ed25519)

This setup implies four rounds for Schnorr:

- One round for exchanging metadata.
- Three rounds for the actual MPC signing protocol (as it is dishonest majority; honest majority would reduce this to two).

> Note: Approver intent signatures are **not** produced by the MPC cluster. Approvers typically sign intents with standard user keys (e.g. ECDSA P-256) which are verified by policy nodes before any MPC transaction signature is produced.

# 🗣️We Are Here to Help!

Please contact us via [email](mailto:support@blockdaemon.com) or support chat if you encounter an issue, bug, or need assistance. Don't forget to include any relevant details about the problem. To request a wallet form and Institutional Vault Approver form, please click [here](/content/support/index.html) or contact [our sales team](/content/get-in-touch/?contact-sales/index.html).

Updated 7 months ago

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