Smart Account & Gas

Every TruthID identity is controlled by an ERC-4337 smart account, not a plain wallet address. This page explains why, what it costs to set up, what day-to-day operations cost, and how to keep the account funded. Read it if you're curious why login doesn't need MetaMask, or you're deciding how much ETH to send during setup. For where this fits into the rest of the protocol — identity creation, device pairing, login — see How TruthID Works.

How it works

TruthID has no relayer and no hot wallet operated by the project — each user's smart account pays its own gas. The smart account (TruthIDAccount.sol, a from-scratch ERC-4337 implementation with no external dependencies) recognizes two tiers of signer:

• Owner — the wallet used to create the identity (Ledger, MetaMask, or any EVM wallet). Full access to the account.
• Devices — the desktop and mobile apps, added after setup. A device can only call execute/executeBatch, and never against the account itself or against DeviceRegistry/IdentityRegistry/RecoveryManager — this stops a compromised device from re-authorizing itself or rewriting who controls the identity.

There's no paymaster. The account deposits ETH directly with the official EntryPoint v0.7 contract and pays for its own UserOperations from that balance — the same EntryPoint every ERC-4337 account on every EVM chain uses, not something TruthID deployed itself.

The account's address is computed with CREATE2 before it exists, from the owner's address — every SDK exports a computeSmartAccountAddress/compute_smart_account_address function (TypeScript, Python, Ruby) if you need to predict it off-chain, with no RPC call and no server involved.

One-time setup

Creating an identity takes one signature and three transactions, all paid by the owner wallet:

1. Sign consent — a message binding the chain ID, registry address, username, and the future smart account address. No gas.
2. Create the identity — IdentityRegistry.createIdentity(username, smartAccountAddress, v, r, s). The signature from step 1 proves the owner actually agreed to this exact smart account address, so nobody can front-run the identity with an address they don't control.
3. Deploy the smart account — TruthIDAccountFactory.createAccount(owner, 0), at the address already committed to in step 2.
4. Fund it — a plain ETH transfer to the new smart account address. The desktop app suggests 0.001 ETH by default; this field is editable, and you can always send more later (see Funding your smart account below).

After that, the owner wallet is only a signature key — it never needs ETH again. Every future operation (pairing a device, creating or revoking a session) is a UserOperation signed off-chain and submitted through a bundler, paid entirely by the smart account.

Day-to-day cost

Once setup is done, there's no wallet popup and no gas prompt. The desktop or mobile app signs a UserOperation locally and submits it to a bundler — Pimlico today, with the bundler URL configurable per user so a self-hosted bundler works too — which forwards it to the EntryPoint. The smart account's own balance covers the gas; nothing is charged to the device, and nobody at TruthID sees or handles the transaction.

Funding your smart account

The smart account is a regular address — send it ETH on Base the same way you'd send it to any wallet. Both apps have a Deposit action (QR code + address) for this: the desktop dashboard and the mobile Wallet tab. There's no minimum balance enforced by the contracts; running out just means the next operation fails until you top it up.

Addresses

TruthIDAccount itself has no fixed address — each owner gets their own instance via CREATE2, deployed on demand by the factory. The factory and the EntryPoint do have fixed addresses — current as of the latest deployment; see Security Model → Audit status for why these addresses have changed before and could again:

Base Mainnet (production, chain ID 8453)

Base Sepolia (testnet, chain ID 84532)

Full function-level reference for both contracts is in Smart Contracts → Contract reference.

Cost

Real gas numbers from the project's own test suite (forge test --gas-report, TruthIDAccount.t.sol + TruthIDAccountFactory.t.sol, 62 tests passing) — not estimates.

What that costs in ETH: at the ~0.011 gwei gas price observed during the mainnet deploy (same rate used throughout Smart Contracts → Cost per operation), the smart account deployment (~1.77M gas) comes out to roughly 0.0000195 ETH, and a day-to-day execute call (~71.5k gas) to roughly 0.0000008 ETH. Gas price moves with network demand — check Base's live gas tracker for the current rate.

These numbers are pure on-chain execution cost, measured locally with Foundry. They don't include whatever a bundler charges on top of gas to submit your UserOperation — Pimlico's free tier adds none today, but that's a bundler-level detail, not something this test suite can measure.

Next steps

• Quickstart — add TruthID login to your backend
• Smart Contracts — addresses, ABIs, and gas cost for every contract
• Security Model — threat model and what TruthID does and doesn't protect against