MPC Wallet
An MPC wallet uses Multi-Party Computation to compute signatures without any single party ever holding the whole private key. The key is split into shares, and signing runs a protocol between shareholders that produces a valid signature without reconstructing the key.
How it works
The wallet generates key shares across two or more parties — typically a device and a server. To sign, the parties exchange messages and jointly compute a signature under a threshold ECDSA or EdDSA scheme. Neither party sees the other’s share or the reconstructed key at any point. If one share is compromised, the attacker still cannot sign. MPC signatures look identical to normal signatures on-chain, so no smart-contract support is required.
Why it matters
MPC removes the single point of failure inherent in a monolithic private key without introducing multisig’s on-chain overhead. It is popular in institutional custody (Fireblocks, Copper) and some consumer wallets (Zengo). The trade-off is that both parties must be online to sign, and the security depends on the correctness of the MPC library and the honesty of the counterparty.
Related concepts
- Shamir Secret Sharing — Shamir Secret Sharing is a cryptographic scheme that splits a secret into N shards such that any T of them can reconstruct the secret, but fewer than T reveal nothing.
- Self-Custody — Self-custody is the practice of holding your own cryptographic keys rather than delegating custody to an exchange or custodian.
- Non-Custodial Wallet — A non-custodial wallet is a wallet in which the user, not a third party, holds the private keys.
- KEK (Key Encryption Key) — A KEK — Key Encryption Key — is a cryptographic key used to encrypt other keys rather than user data directly.
Frequently asked questions
Is MPC the same as multisig?
No. Multisig is on-chain — the chain sees multiple signatures. MPC is off-chain — the chain sees one signature computed jointly.
Is MPC quantum-safe?
Threshold ECDSA inherits ECDSA’s quantum exposure; a large enough quantum computer would break it.
Why does Veyrnox use Shamir instead of MPC?
Shamir is information-theoretically secure, needs no live counterparty at signing, and is simpler to reason about for the specific problem of key backup.
In Veyrnox
Veyrnox uses Shamir Secret Sharing rather than MPC. Shamir is simpler, standard, and does not require a live counterparty at signing time. See Shamir wallet for the trade-offs.