How to decrypt ts files given in a m3u8 file?

Question

I have a url for a m3u8 file which has the list of ts files.All those files are encrypted by AES-128 method.Along with ts files m3u8 file also contains URI for keys.

First I want to download the ts files & then decrypt them.After decryption I want to play those files.

Url for my m3u8 file is like https://example.com/myxml/myclips/250/prog_index.m3u8

My m3u8 file looks like this.

#EXTM3U
#EXT-X-TARGETDURATION:10
#EXT-X-VERSION:2
#EXT-X-MEDIA-SEQUENCE:0
#EXTINF:10, 
#EXT-X-KEY:METHOD=AES-128,URI="https://my.server.com/myxml/myclips/keys/250/crypt_480x272_250_0.key",IV=0x8da4a2d80b88785f7931874bf1e0914b
fileSequence0.ts
#EXTINF:10, 
fileSequence1.ts
#EXTINF:10, 
fileSequence2.ts
#EXTINF:10, 
fileSequence3.ts
#EXTINF:10, 
fileSequence4.ts
#EXTINF:10, 
fileSequence5.ts
#EXTINF:10, 
fileSequence6.ts
#EXTINF:10, 
fileSequence7.ts
#EXTINF:10, 
fileSequence8.ts
#EXTINF:10, 
fileSequence9.ts
#EXTINF:10, 
fileSequence10.ts
#EXTINF:10, 
fileSequence11.ts
#EXTINF:10, 
#EXT-X-KEY:METHOD=AES-128,URI="https://my.server.com/myxml/myclips/keys/250/crypt_480x272_250_1.key",IV=0x8e2d35559338d21f2586e79d6cd5c606
fileSequence12.ts
#EXTINF:10, 
fileSequence13.ts
#EXTINF:10, 
fileSequence14.ts
#EXTINF:10, 
fileSequence15.ts
#EXTINF:10, 
fileSequence16.ts
#EXTINF:10, 
fileSequence17.ts
#EXTINF:10, 
fileSequence18.ts
#EXTINF:10, 
fileSequence19.ts
#EXTINF:2,  
fileSequence20.ts
#EXT-X-ENDLIST

I am not getting any clue how can I do this.Please help.

I am able to download all the ts files.But as those are encrypted so I am not able to play. — Arun Badole, Jan 09 '13 at 12:28
The data seems to be encrypted with AES-128 look for the `CipherInputStream` class. — rekire, Jan 09 '13 at 12:30
I don't understand. The m3u8 listed above should work out of the box. There is no need for you to de-crypt. The mediaframework is able to do that automatically. — Florian Pilz, Jan 09 '13 at 12:36
@FlorianPilz Yes I can play the m3u8 file directly in VideoView.But as per my requirement I have to extract the ts files & then have to play all of them manually.Please help.. — Arun Badole, Jan 09 '13 at 12:42

score 1 · Answer 1 · edited Oct 07 '21 at 07:15

1

As mentioned in my comment, AES-128 decyption is done automatically on Android 3.x & 4.x devices by the mediaframework.

However, there is a mistake in your m3u8. Please reverse the order of #EXTINF and #EXT-X-KEY. #EXTINF requires in the next line to contain the TS URI.

Below a quote from the HLS draft

EXTINF is a record marker that describes the media file identified by the URI that follows it. Each media file URI MUST be preceded by an EXTINF tag.

edited Oct 07 '21 at 07:15

Community

1
1

answered Jan 09 '13 at 12:47

Florian Pilz

337
1
12

But I can play the same m3u8 when I use it with Media Framework & what I want is to decrypt & play ts files. – Arun Badole Jan 09 '13 at 13:03

score 0 · Answer 2 · answered Jun 07 '18 at 15:46

I did almost the same a while ago. I wrote about it here: https://andreasvolkmann.github.io//m3u8-and-ts-segments/

Basically taking a m3u8 playlist with encrypted ts segments and turning it into one mp3 file.

However I'm not on Android. The following code worked for me (Kotlin):

fun getCipher(data: EncryptionData): Cipher {
    val bytes = URL(data.uri).readBytes()
    val chainmode = "CBC"
    val method = when (data.method) {
        EncryptionMethod.AES -> "AES/$chainmode/NoPadding"
        else -> data.method.name
    }
    val keySpec = SecretKeySpec(bytes, data.method.name)
    logger.trace("Decrypting using method ${data.method} ($method)")
    return Cipher
        .getInstance(method)
        .apply { init(Cipher.DECRYPT_MODE, keySpec, IvParameterSpec(ByteArray(16))) }
}

How to decrypt ts files given in a m3u8 file?

2 Answers2