How do I decrypt the HLS stream to a .ts file when I have the key and IV?

Question

I have access to all the .ts files. My .m3u8 starts like this:

#EXTM3U
#EXT-X-VERSION:3
#EXT-X-MEDIA-SEQUENCE:0
#EXT-X-ALLOW-CACHE:YES
#EXT-X-TARGETDURATION:13
#EXT-X-KEY:METHOD=AES-128,URI="https://localserver/get_key?title_id=144", IV=0x4d1acfe1962002a4abedb8b68c65fa93
#EXTINF:12.066667,
1500_144_00000.ts
#EXTINF:9.000000,
1500_144_00001.ts
EXTINF:9.000000,
1500_144_00002.ts
...

... and the .m3u8 continues to show all the .ts files. It gives me the IV, and my Access key is f0d3321327cbaa1aa9ddba07801607442bebaad65b17ca75a15affd5

No I've been searching my brain and the web for an answer on how to decrypt the .ts files (or the concatenated file) and I have seen suggestions using both openssl and ffmpeg but I can not seem to reach all the way with either tool.

From what I've figured I can use the IV and Access_key to decrypt the stream using openssl. I have used the IV=4d1acfe1962002a4abedb8b68c65fa93 (removed 0x).

I have so far tried to with the concatenated file:

openssl aes-128-cbc -d -in concatenatedfile.ts -out decrypted_concatenatedfile.ts -nosalt -iv 4d1acfe1962002a4abedb8b68c65fa93 -K f0d3321327cbaa1aa9ddba07801607442bebaad65b17ca75a15affd5 

But this just gives me

bad decrypt
139793444538016:error:06065064:digital envelope routines:EVP_DecryptFinal_ex:bad decrypt:evp_enc.c:539:

I've seen suggestions that use a .key file and convert that to a readable format. But since I don't have a .key file, but a ready string, I figure this is where I fail.

I've tried using ffmpeg in accordance to this beautiful post by @aergistal.

ffmpeg -i my.m3u8 -c copy output.ts

But here too I seem to fail with my long string key.

Any suggestions on how to proceed using openssl or ffmpeg are very welcome.

Kindly

Answer 1

AES-128 means the key is 128 bits, 16 bytes, or 32 hex characters. Your string is much longer, meaning it cant be the correct key.