Web3 custody

Cryptocurrency wallets, DeFi protocol keys, and NFT marketplace custody all share a structural problem: whoever holds the private key holds the funds. Single-key custody is a known operational risk; multi-sig smart contracts help but are chain-specific and add on-chain overhead. Threshold cryptography gives you chain-agnostic multi-party custody with off-chain coordination.

When to choose this use case

  • You operate a cryptocurrency exchange, custody service, or wallet infrastructure.
  • You need institutional-grade custody with no single point of compromise.
  • You want to enforce multi-stakeholder approval for high-value transactions (withdrawals, treasury moves, governance votes).
  • You need cross-chain custody without deploying separate multi-sig contracts on each chain.

How Confium solves it

A threshold ECDSA key (P-256 or secp256k1) is split across N custody parties. Each party runs a Confium signer process holding one share. To authorize a transaction:

  1. The wallet front-end submits the transaction hash to the coordinator.
  2. The coordinator collects partial signatures from T-of-N custody parties.
  3. The final signature is broadcast to the chain as a standard transaction.

The chain sees a normal ECDSA signature. No multi-sig contract needed; no on-chain overhead; no protocol change.

Architecture

[ Wallet front-end ]
       |
       | submit tx hash + policy
       v
[ Coordinator ] ---------------------------+
   |          |          |                 |
   v          v          v                 v
[Custody 1][Custody 2][Custody 3]    [Custody N]
   |          |          |                 |
   +----------+---- T-of-N quorum --------+
                       |
                       v
              [ Standard ECDSA signature ]
                       |
                       v
              [ Broadcast to chain ]
                       |
                       v
              [ Transparency log anchors event ]

Attribute-based policy

Real custody operations have nuanced policies. The Confium predicate DSL expresses them:

2-of-3 user devices
  for transactions under $1,000

3-of-5 security staff
  for transactions $1,000 – $100,000

5-of-7 board members
  for transactions over $100,000

7-of-9 (board + custody + auditor)
  for cold-storage withdrawals

The coordinator evaluates the predicate per transaction.

Cross-chain

The same threshold key infrastructure works for:

  • Bitcoin (ECDSA over secp256k1)
  • Ethereum (ECDSA over secp256k1)
  • Solana (Ed25519)
  • Aptos / Sui (Ed25519 / ECDSA)
  • Cardano (Ed25519)

One custody stack, many chains.

HSM integration

For the highest-assurance deployments, each custody share can be stored in a hardware HSM accessed via PKCS#11. Confium’s confium-store-pkcs11 backend wraps the HSM access; the share never leaves the HSM in plaintext.

Audit and compliance

Every transaction is anchored in the transparency log. SIEM integration via structured JSON audit records supports SOC 2, NYDFS BitLicense (for US crypto businesses), and the EU’s Markets in Crypto-Assets Regulation (MiCA).

See also