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479af2e192
## Summary This PR adds Moonbeam's CallPermit precompile to DataHaven, enabling gasless meta-transactions through EIP-712 signature-based permissions. Users can sign transaction permits offline, allowing relayers to execute transactions on their behalf while maintaining full security and authentication. ## Key Features ### CallPermit Precompile Functions - **`dispatch(address from, address to, uint256 value, bytes data, uint64[] gasLimit, uint256 deadline, uint8 v, bytes32 r, bytes32 s)`**: Execute permitted calls with signature verification - **`nonces(address owner)`**: Get current nonce for permit validation ### Technical Implementation - **Address**: `0x080A` (2058 in decimal) - **EIP-712 Compliance**: Structured signature validation with proper domain separation - **Nonce Management**: Per-user nonce tracking for replay protection - **Deadline Validation**: Time-bound permits for enhanced security - **Gas Forwarding**: Proper gas limit enforcement and forwarding Depends on https://github.com/datahaven-xyz/datahaven/pull/137 --------- Co-authored-by: Claude <noreply@anthropic.com>
101 lines
2.8 KiB
Markdown
101 lines
2.8 KiB
Markdown
# Call Permit Precompile
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This precompile aims to be a general-purpose tool to perform gas-less
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transactions.
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It allows a user (we'll call her **Alice**) to sign a **call permit** with
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MetaMask (using the EIP712 standard), which can then be dispatched by another
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user (we'll call him **Bob**) with a transaction.
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**Bob** can make a transaction to the **Call Permit Precompile** with the call
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data and **Alice**'s signature. If the permit and signature are valid, the
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precompile will perform the call on the behalf of **Alice**, as if **Alice**
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made a transaction herself. **Bob** is thus paying the transaction fees and
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**Alice** can perform a call without having any native currency to pay for fees
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(she'll still need to have some if the call includes a transfer).
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## How to sign the permit
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The following code is an example that is working in a Metamask-injected webpage.
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**Bob** then need to make a transaction towards the precompile address with the same
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data and **Alice**'s signature.
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```js
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await window.ethereum.enable();
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const accounts = await window.ethereum.request({
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method: "eth_requestAccounts",
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});
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const from = accounts[0];
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const to = "0xbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb";
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const value = 42;
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const data = "0xdeadbeef";
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const gaslimit = 100000;
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const nonce = 0;
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const deadline = 1000;
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const createPermitMessageData = function () {
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const message = {
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from: from,
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to: to,
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value: value,
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data: data,
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gaslimit: gaslimit,
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nonce: nonce,
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deadline: deadline,
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};
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const typedData = JSON.stringify({
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types: {
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EIP712Domain: [
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{ name: "name", type: "string" },
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{ name: "version", type: "string" },
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{ name: "chainId", type: "uint256" },
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{ name: "verifyingContract", type: "address" },
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],
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CallPermit: [
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{ name: "from", type: "address" },
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{ name: "to", type: "address" },
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{ name: "value", type: "uint256" },
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{ name: "data", type: "bytes" },
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{ name: "gaslimit", type: "uint64" },
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{ name: "nonce", type: "uint256" },
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{ name: "deadline", type: "uint256" },
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],
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},
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primaryType: "CallPermit",
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domain: {
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name: "Call Permit Precompile",
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version: "1",
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chainId: 0,
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verifyingContract: "0x000000000000000000000000000000000000080a",
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},
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message: message,
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});
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return {
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typedData,
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message,
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};
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};
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const method = "eth_signTypedData_v4";
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const messageData = createPermitMessageData();
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const params = [from, messageData.typedData];
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web3.currentProvider.sendAsync(
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{
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method,
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params,
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from,
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},
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function (err, result) {
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if (err) return console.dir(err);
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if (result.error) {
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alert(result.error.message);
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return console.error("ERROR", result);
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}
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console.log("Signature:" + JSON.stringify(result.result));
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}
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);
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```
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