.crypt14 file results in "Key file mismatch or crypt12 file is corrupt."

[aldennisa15]

After years of successfully using WhatsApp-Crypt12-Decrypter to access MY chat data, this week it stopped working :-(

WhatsApp on my phone looks to have updated to v2.21.8.17 and is now generating local backups with a .crypt14 extension instead of .crypt12.

Unsurprisingly, WhatsApp-Crypt12-Decrypter chokes on this with the error Key file mismatch or crypt12 file is corrupt.

However, armed with hexdump and a bit cunning, I've worked out how to tweak the python so that it successfully decodes .crypt14 files.

Details to follow shortly and/or a fork etc for anyone else interested.

[aldennisa15]

in a .crypt14 file ... [.py hacks in decrypt12 function shown below in square brackets]
... t2 is at offset 14 [so change to crypt12.seek(14) t2 = crypt12.read(32)]
... iv is at offset 66 [change to crypt12.seek(66) iv = crypt12.read(16)]
... encrypted content starts at offset 99, (I haven't yet worked out the correct amount of footer to remove, but removing 0 seems to result in a successful decryption so far) [change to crypt12.seek(99) primer(tf, crypt12, 0)]

[aldennisa15]

I've also noticed that the 16 bytes at offset 62 to 77 in the key file also appear in the .cryptX file, just like the t bytes at offset 30 to 61 do.

In a .crypt12 file they are at offset 35 to 50.
In a .crypt14 file they are at offset 48 to 63.

In my code I've called these x1 and x2 and do the same equality check as happens for t1 and t2.

In addition, in the .crypt14 file, bytes at 86 to 94 look to contain the WA version number, so in my case 2.21.8.17 - presumably the version that wrote the .crypt14 file. I suspect that when the version number rolls over to more digits (e.g. 2.21.10.10) then the offset to the start of the encrypted content (currently 99 in my backup files) might well change?

[ElDavoo]

andreas-mausch/whatsapp-viewer@7035b9c

This contains a C++ implementation of .crypt14 decrypt

Take also a look here:
andreas-mausch/whatsapp-viewer#114 (comment)
So you are right, no implementation change, just offsets.

[ElDavoo]

@aldennisa15 Do you need to get the key file again from wa's data folder?

[aldennisa15]

@ElDavoo I didn't, I'm using the same key file that worked for .crypt12 files previously.

[ElDavoo]

@aldennisa15 can you make a patch please? I can't manage to patch it on my own for some reason.

[ElDavoo]

I'm stupid lol, I made a pull request #13

[ElDavoo]

@aldennisa15 not working anymore with latest dump.

[ElDavoo]

IV now starts at byte 67, but don't know about the rest.

[ElDavoo]

I found the offsets. Since the project seems dead, i'll keep updating offsets in my fork.

[courious875]

hey guys, amazing work. in your opinion is it doable to convert an unencrypted msgstore.db back to an encrypted crypt12 file ? can it be even done in a way for whatsapp to recognize it and restore the messages from it?
please let me know and many thanks

[ElDavoo]

@courious875 have you tried putting the unencrypted backup in the Databases folder?

[courious875]

@ElDavoo yes and it's working like a charm. as a side-challenge I was trying to re-encrypt .db databases back into .crypt12 format, but no luck so far. WhatsApp would not recognize them, no matter what I tried. In my opinion the header and footer are the problem, as they seem to be very unique that provide very precise info to the WhatsApp server what makes it to be recognized as its own. I can't seem to be able to find anything new on the subject on GitHub or else.

[ElDavoo]

@ElDavoo as a side-challenge I was trying to re-encrypt .db databases back into .crypt12 format, but no luck so far.

This is being worked on here

[courious875]

@ElDavoo Many thanks, I can see that you guys made quite a progress ! Nice work !