2MPC dWallets

Every cross-chain vault on sBridge is a two-party multi-party computation (2MPC) wallet provided through ika.xyz — a dWallet network on the Sui blockchain. The key required to sign transactions on an external chain is split into two independent shares that must both contribute to produce a valid signature.

Key Share Architecture

Key Share A  →  held by the USER (never leaves their device)
Key Share B  →  held by ika.xyz dWallet network (distributed)

Valid signature  =  Share A + Share B  (threshold: 2-of-2)
Unilateral sig   =  impossible — mathematically, not by policy

SwapBlok holds neither key share. ika.xyz holds only Key Share B. Neither party can sign a transaction without the user's explicit co-signature. This applies to every deposit and every withdrawal.

Security Properties

• No single party ever holds a complete signing key — the full key is never assembled in one place
• Compromise of ika.xyz alone cannot produce a valid signature without the user's key share
• Compromise of SwapBlok infrastructure cannot move funds — SwapBlok holds no key material at all
• The 2MPC computation runs on the distributed ika.xyz network, not on SwapBlok servers
• Key Share A never leaves the user's device — it is generated and used locally

ika.xyz dWallet Network

• The dWallet network runs on Sui — a high-throughput Layer 1 with sub-second finality
• Key Share B is itself distributed across multiple ika.xyz nodes — no single ika.xyz node holds the full share
• The network is permissionlessly verifiable — anyone can audit that the MPC protocol was followed correctly
• ika.xyz is an independent protocol; SwapBlok integrates it but does not control it

Supported Signing Schemes