Add support for decrypting using password

[nathantaal]

I made the backup. I have the password. I cannot recreate the backup using a key since the device is no longer with me. Is it possible to add support for decrypting with the password?

[giacomoferretti]

A little update on this: it's not as straightforward as it seems.

If I'm not mistaken, when you login WhatsApp sends you the encrypted "backup_token" (not the correct name) and when you enter the password, it tries to match the hash, and then decrypt it. (Not sure about the whole process, just looked into it "quickly")

[giacomoferretti]

Also found this tgalal/yowsup#3123

[nathantaal]

So basically we would need a salt or something? Anyway the guys in the linked issue also haven't figured it out yet :/

[nathantaal]

Maybe we can keep this issue open to make everyone aware of the issue and to choose the 64 hit encryption key. I'll wait for quantom power... 🤡

[SquadCraftFTW]

So it's possible for this to work with just a password it just hasn't been implemented, right? I lost access to my device and on my new device I'm one password attempt away from the backup being deleted off my google drive permanently. I know that I know the password, I just have many variations of them and I don't remember which one it is specifically.

If password decrypt were to be implemented could I keep guessing the password on my local backup (that won't be deleted) until I get the right one and then use it on my whatsapp app?