Offline FairPlay Streaming on iOS: Unable to create SPC and persist CKC

FairPlay streaming content key persistence

Implementation

We use FairPlay with:

• The AVContentKeySession API for iOS 11+

• The AVAssetResourceLoader API for iOS 10.x

References

We based our implementation on:

• The official Apple developer documentation

• WWDC17 - 504 - Advances in HTTP Live Streaming

• WWDC18 - 507 - AVContentKeySession Best Practices

• WWDC20 - 10655 - Discover how to download and play HLS offline

• Several versions of Apple's HLSCatalog sample project found there

Issues

Everything works fine on most iOS versions, but on iOS 12.x we are facing blocking errors when trying to create SPCs with a valid FairPlay certificate or persisting received CKCs.

SPC Creation

AVContentKeySession

The following line causes the error:

Code Block swift
keyRequest.makeStreamingContentKeyRequestData(forApp: certificate, contentIdentifier: contentIdentifierData, options: [AVContentKeyRequestProtocolVersionsKey: [1]])

AVAssetResourceLoader

The following line causes the error:

Code Block swift
try loadingRequest.streamingContentKeyRequestData(forApp: certificate, contentIdentifier: contentIdentifierData, options: [AVAssetResourceLoadingRequestStreamingContentKeyRequestRequiresPersistentKey: true])

Error log

Code Block 
(Error Domain=AVFoundationErrorDomain Code=-11800 "The operation could not be completed." UserInfo={NSLocalizedFailureReason=An unknown error occurred (-12158), NSLocalizedDescription=The operation could not be completed., NSUnderlyingError=0x2820a55c0 {Error Domain=NSOSStatusErrorDomain Code=-12158 "(null)"}})

CKC persistence

AVContentKeySession

The following line causes the error:

Code Block swift
try keyRequest.persistableContentKey(fromKeyVendorResponse: keyData, options: nil)

AVAssetResourceLoader

The following line causes the error:

Code Block swift
try loadingRequest.persistentContentKey(fromKeyVendorResponse: keyData, options: nil)

Error log

Code Block 
(Error Domain=AVFoundationErrorDomain Code=-11800 "The operation could not be completed." UserInfo={NSLocalizedFailureReason=An unknown error occurred (-12158), NSLocalizedDescription=The operation could not be completed., NSUnderlyingError=0x28104ef40 {Error Domain=NSOSStatusErrorDomain Code=-12158 "(null)"}})

Related issues

Here are different references related to our current issue, that we thought could be of intereset:

1. Stack Overflow - Fairplay stops working on iOS 12.4 and 13

2. Stack Overflow - Error while fetching Server Playback Context when downloading Fairplay enabled videos

What we tried

• Implementing a retry mechanism on the failing methods: obviously does not fix the issue, but it works sometimes.

• Implementing the AVContentKeySession APIs since we were at first only using AVAssetResourceLoader and its delegate protocol: as said earlier, we are facing now the issues with both APIs.

• Removing AVContentKeySession and stop calling asset.resourceLoader.preloadsEligibleContentKeys = true on iOS 12.4+, as suggested in the first Stack Overflow related issue

Does anyone encounter the same issues ? Is there a working solution or a stable workaround ?

Thanks in advance,

William