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createSession

Sign a SigningSessionInfo payload with the client signer and return the credential bundle. The bundle can then drive createSessionSigner for delegated signing.

A session credential lets an ephemeral keypair sign transactions on the primary key's behalf until expireAt. The primary key signs a one-shot SigningSessionInfo covering the session pubkey and expiry; the chain verifies that envelope on every session-signed transaction.

Signature

function createSession(
  client: Client<Signer>,
  parameters: {
    pubKey: Uint8Array
    expireAt: number
  },
): Promise<{
  keyHash: KeyHash
  authorization: StandardCredential
  sessionInfo: SigningSessionInfo
}>

Example

import { createSignerClient, createTransport, testnet, PrivateKeySigner, createSessionSigner } from "@left-curve/sdk"
import { Secp256k1 } from "@left-curve/sdk"
 
const client = createSignerClient({
  chain: testnet,
  transport: createTransport(),
  signer: PrivateKeySigner.fromMnemonic(process.env.DANGO_MNEMONIC!),
})
 
const sessionKey = Secp256k1.makeKeyPair()
const expireAt = Date.now() + 24 * 60 * 60 * 1000 // 24h
 
const bundle = await client.createSession({
  pubKey: sessionKey.getPublicKey(),
  expireAt,
})
 
const sessionSigner = createSessionSigner({
  publicKey: sessionKey.getPublicKey(),
  privateKey: /* sessionKey's private bytes */ new Uint8Array(),
  keyHash: bundle.keyHash,
  sessionInfo: bundle.sessionInfo,
  authorization: bundle.authorization,
})

Parameters

pubKey — Uint8Array. The session key's compressed public key.

expireAt — number. Expiry as a Unix timestamp in milliseconds. The action converts to seconds before signing.

Returns

{ keyHash, authorization, sessionInfo } — authorization is the StandardCredential from the primary key, signing sessionInfo. sessionInfo carries the chain id, session pubkey (base64), and expiry (seconds, as string).

Notes

  • The signer must implement signArbitrary. For session signers, only the primary signer (e.g. PrivateKeySigner) can create new sessions.
  • Throws "unsupported credential type" if the signer returns a non-standard credential.

See also