Milestone Escrow
The client locks the full budget up front, split into milestones. Funds move only on release, arbiter decision or cancellation.
Solidity 0.8.28OpenZeppelin v5ETH / ERC-20
SigmaVault (ERC-4626)
Fee-free ERC-4626 tokenized vault with a deposit cap and inflation-attack protection
ERC-4626OpenZeppelin v5Virtual sharesFoundry
What it is
SigmaVault builds on OpenZeppelin's audited ERC-4626 implementation, so it works out of the box with aggregators, routers and dashboards. Virtual shares with a decimals offset of 6 make the first-depositor inflation attack unprofitable.
A configurable deposit cap is exposed through maxDeposit and maxMint, so integrators see the limit before calling. The vault charges no fees — yield reaches holders directly when assets are transferred in — and withdrawals are never limited by the cap.
The business problem
Treasuries, yield products and savings apps need share-based pooling. Custom share accounting is a common source of bugs — the best known is the first-depositor inflation attack, where an attacker's donation rounds the next depositor's shares down to zero.
How it works
- 1
A user approves the asset and deposits; the vault mints shares according to previewDeposit.
- 2
A strategy or treasury sends profit to the vault, so every share becomes worth more.
- 3
The user redeems shares or withdraws assets and receives their pro-rata part.
- 4
The owner can raise or lower the deposit cap; lowering it only stops new deposits.
Security measures
- Audited OpenZeppelin v5.7 ERC-4626 base; rounding always in the vault's favour
- Inflation-attack mitigation (decimals offset 6), covered by a dedicated test
- Fuzzed: deposit + redeem never returns more than deposited; previews match execution; cap always enforced
- Invariants: solvency and share accounting
- Ownable2Step; the owner can only change the cap, never move user funds
Features
- ERC-4626 standard vault
- Deposit cap via maxDeposit / maxMint
- No deposit, withdrawal or performance fees
- Pro-rata yield accrual
- Withdrawals never capped
Typical use cases
- DAO treasury or corporate savings vaults
- White-label yield products on ERC-4626 infrastructure
- Controlled launches with a staged deposit cap
Known limitations
Fee-on-transfer and rebasing assets are not supported. The vault holds assets idle; strategy integrations would add their own risks and need a separate audit.
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