HTTP Status 412 – Precondition Failed in DRMToday

[paynemax14]

I am trying to find the decryption key of a video stream of an android app. I am using HTTPToolkit to intercept the requests on my PC. I was able to get the .mpd playlist file. However, the HTTPToolkit app does not seem to intercept the request to the license server. There is only a GET request to the URL https://downloads.castlabs.com/r/register/ but it does not seem to be the license verification URL. I searched for URL used for license verification for DRMToday stream and found the URL https://lic.drmtoday.com/license-proxy-widevine/cenc/ but using the url along with the .wvd file obtained from my android device in Pywidevine returns the HTTP Status 412 Precondition failed error. The android streaming app seems to be using prestoPlay by CastLabs for react-native. I am stuck and would really appreciate any help or nudge to the right direction.
Thank you!

[CrymanChen]

Any chance to disclose the APP name so we could investigate into it?

One of my experiences was that GlobalTV, when you input the wrong PSSH, it will return an HTTP 416 error which is to-some-extent similar to this one.

[paynemax14]

The app's name is Video. It is a free app but the videos require payment. I can pm you the mpd link.

[CrymanChen]

Problem solved (I think) via private conversation.

[paynemax14]

Yep, thanks a lot for the help!