Restrict eligible holders

Create an allowlist in the Policy Registry, then apply it when shares are issued, sent, or received. Accounts remain ineligible until the policy admin adds them.

Real-world asset (RWA) tokenization is one of many use cases for the B20 Asset standard. The examples on this page use a stock token for illustration; the same flows apply to other asset types.Coinbase tokenized equities are only available to persons in eligible jurisdictions outside of the U.S.Tokenized securities examples shown for illustration. Base is a general-purpose blockchain; issuance and compliance are the responsibility of the issuer under applicable law.

Demo

New to B20? See the B20 Token Standard for the concepts and a full launch walkthrough. These samples target base-std@v1.0.0, viem@2.55.11, and Base Foundry v1.1.1.

Create and bind the eligibility policy

import { parseEventLogs, type Address } from "viem";
import { account } from "../../shared/clients.js";
import { POLICY_REGISTRY, b20Abi, policyRegistryAbi, scope } from "../abi.js";
import { sendContract } from "../write.js";

export async function restrictStockHolders(token: Address, holders: Address[]) {
  const receipt = await sendContract({ address: POLICY_REGISTRY, abi: policyRegistryAbi, functionName: "createPolicyWithAccounts", args: [account.address, 1, holders] });
  const [created] = parseEventLogs({ abi: policyRegistryAbi, logs: receipt.logs, eventName: "PolicyCreated" });
  for (const policyScope of [scope("MINT_RECEIVER_POLICY"), scope("TRANSFER_SENDER_POLICY"), scope("TRANSFER_RECEIVER_POLICY")]) {
    await sendContract({ address: token, abi: b20Abi, functionName: "updatePolicy", args: [policyScope, created.args.policyId] });
  }
  return created.args.policyId;
}

    function restrictStock(address token, address admin, address[] memory holders) public returns (uint64 id) {
        id = StdPrecompiles.POLICY_REGISTRY.createPolicyWithAccounts(
            admin, IPolicyRegistry.PolicyType.ALLOWLIST, holders
        );
        IB20(token).updatePolicy(B20Constants.MINT_RECEIVER_POLICY, id);
        IB20(token).updatePolicy(B20Constants.TRANSFER_SENDER_POLICY, id);
        IB20(token).updatePolicy(B20Constants.TRANSFER_RECEIVER_POLICY, id);
    }

CREATE_TX=$(base-cast send "$POLICY_REGISTRY" \
  "createPolicyWithAccounts(address,uint8,address[])" "$ADMIN" 1 "[$ALICE,$BOB]" \
  --rpc-url "$RPC_URL" --private-key "$PRIVATE_KEY" --json | jq -r .transactionHash)
POLICY_TOPIC=$(base-cast receipt "$CREATE_TX" --rpc-url "$RPC_URL" --json | jq -r '.logs[0].topics[1]')
POLICY_ID=$(base-cast to-dec "$POLICY_TOPIC")
for SCOPE in MINT_RECEIVER_POLICY TRANSFER_SENDER_POLICY TRANSFER_RECEIVER_POLICY; do
  base-cast send "$TOKEN_ADDRESS" "updatePolicy(bytes32,uint64)" "$(base-cast keccak "$SCOPE")" "$POLICY_ID" \
    --rpc-url "$RPC_URL" --private-key "$PRIVATE_KEY"
done

See the complete verified B20 examples for imports, client construction, and runnable projects.

The same allowlist policy gates mint recipients, transfer senders, and transfer recipients.

Seed all intended holders before binding an allowlist. An unlisted account becomes ineligible immediately.

Build on Base

Issue Stablecoins

Integrate DeFi

Issue RWA

Accept Payments

Private Transactions

Demo

Create and bind the eligibility policy

See also

​Demo

​Create and bind the eligibility policy

​See also

Demo

Create and bind the eligibility policy

See also