Session Keys

No need to sign each transactions !

To activate session keys, we will switch the fallback handler of your safe to the ERC7579 implementation.

For now, our session keys only allow the whitelisting of contract with functions, soon we'll add spending limits, timeframe and other features.

1 - Create a Session Key

import { generatePrivateKey, privateKeyToAccount } from "viem/accounts";
import {
    type ComethSmartAccountClient,
    type SafeSigner,
    erc7579Actions,
    smartSessionActions,
} from "@cometh/connect-sdk-4337";

export const COUNTER_CONTRACT_ADDRESS =
    "0x4FbF9EE4B2AF774D4617eAb027ac2901a41a7b5F";


const safe7559Account = smartAccountClient.extend(smartSessionActions())
            .extend(erc7579Actions());

const privateKey = generatePrivateKey();
const sessionOwner = privateKeyToAccount(privateKey);

const createSessionsResponse = await safe7559Account.grantPermission({
    sessionRequestedInfo: [
        {
            sessionPublicKey: sessionOwner.address,
            actionPoliciesInfo: [
                {
                    contractAddress: COUNTER_CONTRACT_ADDRESS,
                    functionSelector: toFunctionSelector(
                        "function count()"
                    ) as Hex,
                },
            ],
        },
    ],
});

await safe7559Account.waitForUserOperationReceipt({
    hash: createSessionsResponse.userOpHash,
});

2 - Store the Session Key

In our example, we will store the session key details in local storage. You are free to store it wherever you want.

import { SmartSessionMode } from "@rhinestone/module-sdk";

const sessionData = {
    granter: smartAccountClient?.account?.address as Address,
    privateKey: privateKey,
    sessionPublicKey: sessionOwner.address,
    description: `Session to increment a counter`,
    moduleData: {
        permissionIds: createSessionsResponse.permissionIds,
        action: createSessionsResponse.action,
        mode: SmartSessionMode.USE,
        sessions: createSessionsResponse.sessions,
    },
};

// This is for example purposes.
const sessionParams = stringify(sessionData);

localStorage.setItem(
    `session-key-${smartAccountClient?.account?.address}`,
    sessionParams
);

3 - Use the Session Key

import {
    createComethPaymasterClient,
    createSafeSmartAccount,
    createSmartAccountClient,
    smartSessionActions,
    toSmartSessionsSigner
} from "@cometh/connect-sdk-4337";
import { generatePrivateKey, privateKeyToAccount } from "viem/accounts";

const apiKey = process.env.COMETH_API_KEY;
const bundlerUrl = process.env.4337_BUNDLER_URL;
const paymasterUrl = process.env.4337_PAYMASTER_URL
const publicClient = createPublicClient({
    chain,
    transport: http(),
});


const stringifiedSessionData = localStorage.getItem(
    `session-key-${WALLETADDRESS}`
);
const sessionData = parse(stringifiedSessionData);

const sessionKeySigner = await toSmartSessionsSigner(safe7559Account, 
{
    moduleData: sessionData.moduleData,
    signer: privateKeyToAccount(sessionData.privateKey),
})

const sessionKeyAccount = await createSafeSmartAccount({
    apiKey,
    chain,
    smartAccountAddress: smartAccountClient?.account?.address,
    smartSessionSigner: sessionKeySigner,
});

const paymasterClient = await createComethPaymasterClient({
    transport: http(paymasterUrl),
    chain,
});

const sessionKeyClient = createSmartAccountClient({
    account: sessionKeyAccount,
    chain,
    bundlerTransport: http(bundlerUrl),
    paymaster: paymasterClient,
    userOperation: {
        estimateFeesPerGas: async () => {
            return await paymasterClient.getUserOperationGasPrice();
        },
    },
}).extend(smartSessionActions());

const callData = encodeFunctionData({
    abi: countContractAbi,
    functionName: "count",
});

const hash = await sessionKeyClient.usePermission({
    actions: [
        {
            target: COUNTER_CONTRACT_ADDRESS,
            callData: callData,
            value: BigInt(0),
        },
    ],
});