iOS 16: AVContentKeyRequest processContentKeyResponse Throws Exception

Question

Issue:

I am supporting a streaming iOS application that uses Fairplay DRM to playback protected content.

On iOS 16 devices, I am seeing intermittent exceptions thrown when trying to process the CKC returned by the license server.

The thrown exception is as follows:

-[AVContentKeyRequest processContentKeyResponse:] AVContentKeySession's keySystem is not same as that of keyResponse"

This issue does not occur on older devices (we support iOS 13, 14, 15).

I am unable to find much documentation about this error so any insight is appreciated:

Code Overview

• Use ContentKeyRequest to request an application certificate
• Use returned Cert to call makeStreamingContentKeyRequestData
• Use returned data to request FairPlay license
• Use returned CKC to generate AVContentKeyResponse (i.e. AVContentKeyResponse(fairPlayStreamingKeyResponseData)
• Call processContentKeyResponse(_)
• App crash/exception thrown when callling processContentKeyResponse

I am seeing other issues related to DRM and iOS 16 but none seem to match my particular problem. i.e. I am not dealing with downloaded content and offline DRM

• AVContentKeySessionDelegate methods not called on iOS 16
• iOS 16 FairPlay Changes

• Hackerman: Did you figure out what was causing this?
• rmigneco: @hackerman - not yet.
• Hackerman: I think this happens when the response is being called as ContentKeySession is being shutdown. Just a theory.
• rmigneco: @Hackerman I've noticed it when tuning into an asset for the first time or sometimes when retuning it. Its often very intermittent

Answer 1

For me, this error is thrown when the content is dismissed before FairPlay has a chance to process the content key:

let keyResponse = AVContentKeyResponse(fairPlayStreamingKeyResponseData: ckcData)
// Error happens at this point if request is active
keyRequest.processContentKeyResponse(keyResponse)

Since I'm using Alamofire to make the certificate, SPC, and CKC calls, stopping all the requests immediately upon dismissing the content prevented the key processing:

Alamofire.Session.default.getAllTasks { tasks in
 tasks.forEach{ 0ドル.cancel() }
}

Of course this may not be an ideal approach, but let me know if anyone finds a better way.

• rmigneco: Thanks for the response. So your suggestion is to not call processContentKeyResponse if the content is being abandoned in some way? i.e. User dismisses view, etc.
• 6rchid: @rmigneco That's right! That was at least the root of my problem