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48 lines
1.7 KiB
JavaScript
48 lines
1.7 KiB
JavaScript
1 year ago
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function toEthSignedMessageHash(messageHex) {
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const messageBuffer = Buffer.from(messageHex.substring(2), 'hex');
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const prefix = Buffer.from(`\u0019Ethereum Signed Message:\n${messageBuffer.length}`);
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return web3.utils.sha3(Buffer.concat([prefix, messageBuffer]));
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}
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/**
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* Create a signer between a contract and a signer for a voucher of method, args, and redeemer
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* Note that `method` is the web3 method, not the truffle-contract method
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* @param contract TruffleContract
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* @param signer address
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* @param redeemer address
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* @param methodName string
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* @param methodArgs any[]
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*/
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const getSignFor =
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(contract, signer) =>
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(redeemer, methodName, methodArgs = []) => {
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const parts = [contract.address, redeemer];
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const REAL_SIGNATURE_SIZE = 2 * 65; // 65 bytes in hexadecimal string length
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const PADDED_SIGNATURE_SIZE = 2 * 96; // 96 bytes in hexadecimal string length
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const DUMMY_SIGNATURE = `0x${web3.utils.padLeft('', REAL_SIGNATURE_SIZE)}`;
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// if we have a method, add it to the parts that we're signing
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if (methodName) {
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if (methodArgs.length > 0) {
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parts.push(
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contract.contract.methods[methodName](...methodArgs.concat([DUMMY_SIGNATURE]))
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.encodeABI()
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.slice(0, -1 * PADDED_SIGNATURE_SIZE),
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);
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} else {
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const abi = contract.abi.find(abi => abi.name === methodName);
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parts.push(abi.signature);
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}
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}
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// return the signature of the "Ethereum Signed Message" hash of the hash of `parts`
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const messageHex = web3.utils.soliditySha3(...parts);
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return web3.eth.sign(messageHex, signer);
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};
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module.exports = {
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toEthSignedMessageHash,
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getSignFor,
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};
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