Build an Ethereum account Alice and Bob can use

Create one shared Ethereum account, let Alice and Bob each send a transaction, and verify that Mallory is refused. The app uses tasra-sdk as its only runtime dependency. It creates its own wallets, credentials and slot; no learner account, private key, slot ID or CLI setup is copied from another project.

Install the latest SDK from npm in step 2. Check deployment compatibility before running the app.

1. Prepare the network connection

Install Node.js 22.12+ (24 recommended). The example downloads the testnet pointer and manifest from tasra-releases and checks the manifest checksum. It resolves the RPC, contracts and verifier from that configuration, with an explicit lowest-operator-id coordinator convention.

The selected deployment must support tECDSA key generation, creator-signed rule provisioning, OID4VP authorization and transaction signing. This example requests 2-of-3 keepers and a 2-of-3 verifier policy, using SD-JWT credentials bound to fresh did:jwk identities. A manifest or registry check does not establish support for those operations. Any deployment-specific usage credits must also be available.

The application generates its own creator wallet and prints its public address. Fund it with AVAX using the official Fuji C-Chain faucet or a wallet you control. No shared private key or precreated learner account is required.

2. Create your application

In a new terminal, create the project and install the latest SDK from npm:

mkdir my-shared-account
cd my-shared-account
npm init -y
npm pkg set type=module
npm install tasra-sdk@latest
npm install --save-dev typescript tsx @types/node
cp node_modules/tasra-sdk/examples/shared-account.ts app.ts
cp node_modules/tasra-sdk/examples/tutorial-support.ts tutorial-support.ts
cp node_modules/tasra-sdk/examples/tutorial-negative.ts tutorial-negative.ts
cp node_modules/tasra-sdk/examples/network.ts network.ts
cp node_modules/tasra-sdk/examples/fund-slot.ts .

These copy commands use a macOS/Linux shell or WSL. You can copy the same files with your IDE. Open app.ts: it contains the slot, credential and wallet operations. tutorial-support.ts supplies shared network and identity setup and public evidence output; tutorial-negative.ts exercises verifier rejection. The SDK implements slot orchestration, credential creation and wallet signing.

Save .gitignore with this line:

.tasra/

Save tsconfig.json:

{
  "compilerOptions": {
    "target": "ES2022",
    "module": "NodeNext",
    "moduleResolution": "NodeNext",
    "resolveJsonModule": true,
    "strict": true,
    "skipLibCheck": true,
    "noEmit": true,
    "types": ["node"]
  },
  "include": ["*.ts"]
}

3. Check and execute

Before protected operations, the terminal example pauses for TSRA usage credit. In a second terminal in the same project, run its printed fund-slot.ts ... status command. Follow Fund a slot to obtain EURC, buy TSRA from BondingCurve, and deposit TSRA into the printed slot. Replace .tasra/first-slot in those commands with this app’s printed directory. Fund every new slot; creator AVAX pays gas and does not provide usage credits. The app waits up to 15 minutes per slot.

First typecheck the app (the same command on macOS, Linux and Windows):

npx tsc --noEmit

Run the application:

npx tsx network.ts
npx tsx app.ts

The app prints its creator address and chain, then waits up to 15 minutes for at least 0.05 AVAX. In a separate window, use the network’s faucet or transfer native tokens from a wallet you control. Fund the printed address on the printed chain. The creator pays setup transactions and funds the shared account’s transaction gas.

Key generation and threshold signing can take time. The app records the shared account address, Alice’s and Bob’s confirmed transactions, and Mallory’s refusal. It prints the evidence location at the end.

Each invocation starts a fresh demonstration with a new slot and isolated private store. An interrupted invocation is not resumed by starting the tutorial again. Preserve its store and reconcile any pending transactions first. The SDK’s named operations support resuming the same intent when your application reopens the same store; see recovery boundaries.

4. Read the application

Step	Application API	Result
Connect	new TasraClient({manifest, store})	Public deployment configuration and private durable state.
Create users	tasra.identities.create, tasra.credentials.issue	A fresh issuer and separate holder-bound credentials.
Define access	tasra.credentials.policy	Only the intended credential holders can request signing.
Create the account	tasra.slots.create with mode: 'ecdsa'	Commitment, creation, key generation and rule provisioning handled by the SDK.
Send transactions	tasra.credentials.authorize, tasra.wallets.fromSlot, transfer	Each exact transaction is authorized, signed and confirmed.
Check refusal	The separate negative-test helper submits a nonmatching presentation	The verifier refuses Mallory and the account nonce does not change.

Two of three keepers cooperate to sign. Either authorized user, Alice or Bob, may initiate a transaction; this is not a two-user approval workflow. The app submits zero-value self-transfers with nonces 0 and 1 from the same account. It checks the receipts and verifies that Mallory’s request leaves the nonce at 2. The refusal must come from the verifier; local credential filtering is not counted as server-side evidence.

For two people approving one signature, use native approvals. For two independent document signatures, use document signing.

5. Check the results

Open the printed run directory:

• evidence.json: the slot/account, confirmed transactions and verifier-refusal result.
• alice-receipt.json and bob-receipt.json: the actual chain receipts.

The evidence records public account activity. The rest of .tasra/ contains private identities, credentials and recovery state. Share only reviewed evidence files, never the entire directory.

If it stops

Symptom	Next action
Cannot import tasra-sdk/app	Run npm install tasra-sdk@latest inside your app directory.
Missing configuration or helper file	Copy every file listed in step 2 and run from the app folder.
Connection refused	Check RPC access and the downloaded release manifest.
Certificate verification failure	Check the service certificate and system trust; keep TLS verification enabled.
Slot is not ready	Inspect its DKG status and preserve the private store.
No keeper accepted the rule	Confirm creator-signed provisioning support and the selected deployment identity.
Authorization refused for Alice/Bob	Check issuer and verifier compatibility; a denial is not a connectivity retry.
Submission outcome is uncertain	Reconcile the recorded hash before retrying; do not discard the journal.

Application source · Application API · Documentation index

npx tsx network.ts saves the verified manifest and its checksum pin. Keep both files with the application so restarts use the same deployment. The examples use lowest-operator-id as the explicit coordinator convention; confirm it matches the selected service. Fund each newly printed creator address with at least 0.05 AVAX on Fuji before continuing; more may be needed if gas costs rise.