harden-runner/src/checksum.ts

import * as core from "@actions/core";
import * as crypto from "crypto";
import * as fs from "fs";

export function verifyChecksum(downloadPath: string) {
  const fileBuffer: Buffer = fs.readFileSync(downloadPath);
  const checksum: string = crypto
    .createHash("sha256")
    .update(fileBuffer)
    .digest("hex"); // checksum of downloaded file

  const expectedChecksum: string =
    "c1286b469a2ad8657d69cf96dfaa5b9166ee6fa46d46fcb9d454d5851aa964bd"; // checksum for v0.9.4

  if (checksum !== expectedChecksum) {
    core.setFailed(
      `Checksum verification failed, expected ${expectedChecksum} instead got ${checksum}`
    );
  }

  core.debug("Checksum verification passed.");
}