VEYRNOX · Learn · Transaction Simulation
Transaction Simulation
Transaction simulation is a pre-signing check that runs a proposed transaction against a forked node state and reports the expected net asset change to the user before they sign. It exposes hidden drainer behaviour that a raw call-data view cannot.
How it works
The wallet submits the unsigned transaction to a simulation service that forks the current chain state, executes the transaction against the fork, and returns the resulting state diff — which tokens moved, which NFTs transferred, which approvals were granted, and to whom. The wallet renders this as a plain-language summary: "You send 1.2 ETH, 5,000 USDC, and 3 NFTs. You receive nothing." A drainer contract that presents itself as a mint is exposed as a large outbound sweep.
Why it matters
Raw transaction data is unreadable — hex-encoded call data and opaque contract targets. Signing without simulation is signing blind. Simulation makes the actual on-chain effect visible before signing, which is the only defence that works against sophisticated drainers whose surface appearance is legitimate.
Related concepts
- Drainer Contract — A drainer contract is a malicious smart contract that, once approved by a victim, transfers assets out of the victim’s wallet to attacker-controlled addresses.
- Phishing Site Detection — Phishing site detection is the wallet-level defence that blocks connections to fraudulent domains impersonating legitimate dApps, exchanges, or bridges.
- Threat Intelligence Platform (TIP) — A Threat Intelligence Platform (TIP) is a backend service that aggregates, curates, and distributes real-time threat signals — phishing domains, drainer contracts, sanctioned addresses, suspicious dApps — to consuming clients.
- WalletConnect v2 — WalletConnect v2 is an open protocol that lets a wallet on one device connect to a dApp on another — most commonly a mobile wallet paired with a desktop dApp — over an end-to-end-encrypted relay.
Frequently asked questions
Does simulation catch every attack?
No. It catches attacks whose on-chain effect differs from the stated intent. State-dependent attacks (that trigger later) require additional checks.
Does simulation leak my transaction to a third party?
The simulation service sees the transaction data. Veyrnox uses simulation providers with strict data-retention limits and no user linkage.
How fast is simulation?
A few hundred milliseconds in the common case, run in parallel with the confirmation prompt.
In Veyrnox
Transaction simulation is a Safety Plus and AI Security Protection feature. The AI Security Advisor uses the simulation output to raise blocking warnings on large negative deltas, not just to display them.