thirdwebDocs

EcosystemWallet.CreateSessionKey

Creates a session key for the user wallet with EIP-7702 functionality. Session keys allow delegated access to the wallet with specific permissions and time constraints. This method is only supported for EIP7702 and EIP7702Sponsored execution modes.

How it works: The method creates a SessionSpec with your parameters, signs it using EIP-712, and calls createSessionWithSig on the EIP-7702 account contract to register the session key on-chain.

Usage

// Create a session key for 24 hours with full permissions
var receipt = await ecosystemWallet.CreateSessionKey(
    chainId: 1,
    signerAddress: await sessionSigner.GetAddress(),
    durationInSeconds: 86400, // 24 hours
    grantFullPermissions: true
);
 
// Create a session key with specific call and transfer policies
var callPolicies = new List<CallSpec>
{
    new CallSpec
    {
        Target = "0x1234567890123456789012345678901234567890",
        Selector = new byte[] { 0xa9, 0x05, 0x9c, 0xbb }, // transfer(address,uint256)
        MaxValuePerUse = BigInteger.Parse("100000000000000000"), // 0.1 ETH max per call
        ValueLimit = new UsageLimit
        {
            LimitType = 1, // Lifetime limit
            Limit = BigInteger.Parse("1000000000000000000"), // 1 ETH total
            Period = 86400 // 1 day period
        },
        Constraints = new List<Constraint>
        {
            new Constraint
            {
                Condition = 1, // Equal to (not 0)
                Index = 0, // First parameter (to address)
                RefValue = new byte[32], // Reference value for validation
                Limit = new UsageLimit
                {
                    LimitType = 2, // Allowance (not 0)
                    Limit = BigInteger.Parse("500000000000000000"), // 0.5 ETH per period
                    Period = 3600 // 1 hour
                }
            }
        }
    }
};
 
var transferPolicies = new List<TransferSpec>
{
    new TransferSpec
    {
        Target = "0x0000000000000000000000000000000000000000", // ETH transfers
        MaxValuePerUse = BigInteger.Parse("100000000000000000"), // 0.1 ETH max per transfer
        ValueLimit = new UsageLimit
        {
            LimitType = 1, // Lifetime limit
            Limit = BigInteger.Parse("1000000000000000000"), // 1 ETH total
            Period = 86400 // 1 day
        }
    },
    new TransferSpec
    {
        Target = "0xA0b86a33E6411a3bb4CC4C7b9C5C5C7C7C8C9C0c", // Specific token contract
        MaxValuePerUse = BigInteger.Parse("1000000000000000000000"), // 1000 tokens max per transfer
        ValueLimit = new UsageLimit
        {
            LimitType = 2, // Allowance (resets every period)
            Limit = BigInteger.Parse("10000000000000000000000"), // 10,000 tokens per period
            Period = 3600 // 1 hour period
        }
    }
};
 
var receipt = await ecosystemWallet.CreateSessionKey(
    chainId: 1,
    signerAddress: await sessionSigner.GetAddress(),
    durationInSeconds: 3600, // 1 hour
    grantFullPermissions: false,
    callPolicies: callPolicies,
    transferPolicies: transferPolicies,
    uid: System.Text.Encoding.UTF8.GetBytes("unique-session-id") // Custom unique identifier
);
 
// Create a wildcard session key (works with any address)
var wildcardReceipt = await ecosystemWallet.CreateSessionKey(
    chainId: 1,
    signerAddress: "0x0000000000000000000000000000000000000000", // Wildcard address
    durationInSeconds: 7200, // 2 hours
    grantFullPermissions: true
);

Common Use Cases

Gaming Session Key

// Allow spending game tokens with daily limits
var gameTokenPolicy = new List<CallSpec>
{
    new CallSpec
    {
        Target = "0xGameTokenContract...", 
        Selector = new byte[] { 0xa9, 0x05, 0x9c, 0xbb }, // transfer(address,uint256)
        MaxValuePerUse = BigInteger.Parse("1000000000000000000000"), // 1000 tokens per transaction
        ValueLimit = new UsageLimit
        {
            LimitType = 2, // Allowance (resets daily)
            Limit = BigInteger.Parse("10000000000000000000000"), // 10,000 tokens per day
            Period = 86400 // 1 day
        }
    }
};

DeFi Trading Session Key

// Allow DEX trades with specific token constraints
var dexTradingPolicy = new List<CallSpec>
{
    new CallSpec
    {
        Target = "0xUniswapV3Router...",
        Selector = new byte[] { 0x41, 0x4b, 0xf3, 0x89 }, // exactInputSingle
        MaxValuePerUse = BigInteger.Parse("100000000000000000"), // 0.1 ETH max per trade
        ValueLimit = new UsageLimit
        {
            LimitType = 2, // Daily allowance
            Limit = BigInteger.Parse("1000000000000000000"), // 1 ETH per day
            Period = 86400
        },
        Constraints = new List<Constraint>
        {
            new Constraint
            {
                Condition = 1, // Equal - only allow specific token
                Index = 0, // First parameter (tokenIn)
                RefValue = new byte[32], // USDC token address (padded to 32 bytes)
                Limit = new UsageLimit { LimitType = 0 } // Unlimited usage of this constraint
            }
        }
    }
};

Subscription Payment Session Key

// Allow recurring payments to specific service
var subscriptionPolicy = new List<CallSpec>
{
    new CallSpec
    {
        Target = "0xSubscriptionContract...",
        Selector = new byte[] { 0x12, 0x34, 0x56, 0x78 }, // paySubscription()
        MaxValuePerUse = BigInteger.Parse("50000000000000000000"), // $50 worth of tokens
        ValueLimit = new UsageLimit
        {
            LimitType = 2, // Monthly allowance
            Limit = BigInteger.Parse("50000000000000000000"), // $50 per month
            Period = 2592000 // 30 days
        },
        Constraints = new List<Constraint>
        {
            new Constraint
            {
                Condition = 1, // Equal - only allow payments to specific service
                Index = 0, // Service ID parameter
                RefValue = BitConverter.GetBytes(12345).Concat(new byte[28]).ToArray(), // Service ID 12345
                Limit = new UsageLimit { LimitType = 0 }
            }
        }
    }
};

Emergency Withdrawal Session Key

// Allow emergency withdrawals with strict limits
var emergencyPolicy = new List<TransferSpec>
{
    new TransferSpec
    {
        Target = "0x0000000000000000000000000000000000000000", // ETH
        MaxValuePerUse = BigInteger.Parse("100000000000000000"), // 0.1 ETH per withdrawal
        ValueLimit = new UsageLimit
        {
            LimitType = 1, // Lifetime limit
            Limit = BigInteger.Parse("500000000000000000"), // 0.5 ETH total
            Period = 0 // Not used for lifetime limits
        }
    }
};
 
var emergencyReceipt = await ecosystemWallet.CreateSessionKey(
    chainId: 1,
    signerAddress: await emergencyWallet.GetAddress(),
    durationInSeconds: 604800, // 1 week
    grantFullPermissions: false,
    callPolicies: null,
    transferPolicies: emergencyPolicy
);