[krystallinity]

Originally Posted by BlueCop

I haven't used flex. I will check it out.

I found something interesting. The KeyID is the same for the HLS and DASH streams(just endian swapped but flagged as such). This makes me think the keys we have for the SD will work for for HD.

The problem is I think they are using subsample encryption. This mixes encrypted and unencrypted data.

The video track is divided into samples and sub samples. The M3U8 actually just provides the offset and length of each sample. The samples are sub divided into subsamples with unencrypted parts. All encrypted sub samples are treated as a contiguous block for decryption though. So we would need a way to read the subsamples are a contiguous segment to decrypt it properly. I don't know the proper way to read the needed meta-data to accomplish this.

So I believe we have everything to decrypt the HD streams but need a way to properly decrypt it.

I am looking into libraries that could parse the mp4 atoms for me. I found the PIFF Sample Encryption box atom which has the list of IVs and which parts are encrypted and which parts are clear.

Thanks for all of this research! This is getting me all excited!