client-reverse

First capture the real request and replay it unchanged, since many signatures are replayable as-is. If mutation breaks it, trace backward from the sign field in Chrome DevTools using XHR breakpoints to find the writer and builder, then either reimplement the signer in Python or call the page's own sign function.

Set an XHR/fetch breakpoint on the endpoint path in DevTools Sources, trigger the action, and walk up the Call Stack to the frame that writes the header or body field. Pretty-print the bundle and use global search for the field name to locate the writer quickly.

Full SDK reversal is out of scope for a single bounty. Instead, reuse one fresh valid token within its validity window, or drive a headless browser with Selenium or Playwright to mint tokens and hand them to your Python fuzzer.

The two usual causes are JSON key ordering and separator whitespace, and the concatenation order of the input fields. Log the pre-hash message string the app builds at a breakpoint and diff it against yours rather than comparing final digests.

No, reversing the signing algorithm alone is not a valid finding. Reportable issues include signatures that omit the endpoint or payload, missing freshness checks enabling replay, hardcoded secrets in the bundle, and the IDOR or access-control bugs you reach behind the signature.

Yes, the same packet-first spine applies. Drive the app through Burp or mitmproxy first, and only use jadx for static analysis or frida and objection for runtime hooking when the traffic is encrypted or unreplayable.