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import fs from 'fs'
import { program } from 'commander'
import { BigNumber, utils } from 'ethers'
program
.version('0.0.0')
.requiredOption(
'-i, --input <path>',
'input JSON file location containing the merkle proofs for each account and the merkle root'
)
program.parse(process.argv)
const json = JSON.parse(fs.readFileSync(program.input, { encoding: 'utf8' }))
const combinedHash = (first: Buffer, second: Buffer): Buffer => {
if (!first) {
return second
}
if (!second) {
return first
}
return Buffer.from(
utils
.solidityKeccak256(
['bytes32', 'bytes32'],
[first, second].sort(Buffer.compare)
)
.slice(2),
'hex'
)
}
const toNode = (
index: number | BigNumber,
account: string,
amount: BigNumber
): Buffer => {
const pairHex = utils.solidityKeccak256(
['uint256', 'address', 'uint256'],
[index, account, amount]
)
return Buffer.from(pairHex.slice(2), 'hex')
}
const verifyProof = (
index: number | BigNumber,
account: string,
amount: BigNumber,
proof: Buffer[],
expected: Buffer
): boolean => {
let pair = toNode(index, account, amount)
for (const item of proof) {
pair = combinedHash(pair, item)
}
return pair.equals(expected)
}
const getNextLayer = (elements: Buffer[]): Buffer[] => {
return elements.reduce<Buffer[]>((layer, el, idx, arr) => {
if (idx % 2 === 0) {
// Hash the current element with its pair element
layer.push(combinedHash(el, arr[idx + 1]))
}
return layer
}, [])
}
const getRoot = (
_balances: { account: string; amount: BigNumber; index: number }[]
): Buffer => {
let nodes = _balances
.map(({ account, amount, index }) => toNode(index, account, amount))
// sort by lexicographical order
.sort(Buffer.compare)
// deduplicate any eleents
nodes = nodes.filter((el, idx) => {
return idx === 0 || !nodes[idx - 1].equals(el)
})
const layers = []
layers.push(nodes)
// Get next layer until we reach the root
while (layers[layers.length - 1].length > 1) {
layers.push(getNextLayer(layers[layers.length - 1]))
}
return layers[layers.length - 1][0]
}
if (typeof json !== 'object') {
throw new Error('Invalid JSON')
}
const merkleRootHex = json.merkleRoot
const merkleRoot = Buffer.from(merkleRootHex.slice(2), 'hex')
const balances: { index: number; account: string; amount: BigNumber }[] = []
let valid = true
Object.keys(json.claims).forEach((address) => {
const claim = json.claims[address]
const proof = claim.proof.map((p: string) => Buffer.from(p.slice(2), 'hex'))
balances.push({
index: claim.index,
account: address,
amount: BigNumber.from(claim.amount),
})
if (verifyProof(claim.index, address, claim.amount, proof, merkleRoot)) {
console.log('Verified proof for', claim.index, address)
} else {
console.log('Verification for', address, 'failed')
valid = false
}
})
if (!valid) {
console.error('Failed validation for 1 or more proofs')
process.exit(1)
}
console.log('Done!')
// Root
const root = getRoot(balances).toString('hex')
console.log('Reconstructed merkle root', root)
console.log(
'Root matches the one read from the JSON?',
root === merkleRootHex.slice(2)
)