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Time

Cardano uses a slot-based time system. Each slot has a fixed duration (typically 1 second on mainnet), and transactions reference slots for validity ranges. Evolution SDK handles the conversion between Unix timestamps and slots automatically.

Key Concepts​

ConceptDescription
SlotA numbered time unit on the blockchain
Unix TimeMilliseconds since epoch (standard POSIX time)
Validity RangeTime window during which a transaction is valid
Slot ConfigNetwork-specific mapping between slots and Unix time

How It Works​

When you call .setValidity({ from, to }), you provide Unix timestamps in milliseconds. The transaction builder converts these to slots using the network's slot configuration:

import { preprod, Client } from "@evolution-sdk/evolution"

const client = Client.make(preprod)
  .withBlockfrost({
    baseUrl: "https://cardano-preprod.blockfrost.io/api/v0",
    projectId: process.env.BLOCKFROST_API_KEY!
  })
  .withSeed({ mnemonic: process.env.WALLET_MNEMONIC!, accountIndex: 0 })

const now = BigInt(Date.now())

// Set validity: valid from now, expires in 5 minutes
// await client.newTx()
//   .setValidity({ from: now, to: now + 300_000n })
//   ...

Next Steps​