Suggestion: How to get the prerequisites done?

[MaxWolodin]

Thank you very much for the tool @residentsummer. Unfortunately I wasted pretty much time to get 2 of the prerequisites done. This was caused by many outdated tutorials that are no longer applicable to a current android version.
Therefore I suggest you to also describe how to get the prerequisites done:

Decrypted msgstore.db from Android

Due to the sandboxing of current android OS it is to my knowledge no longer possible to extract the Whatsapp decryption key from an unrooted device. I have tried many older solutions but none of them worked, due to security restrictions.

Download msgstore.db.cryptXY

Download the msgstore from your phone via Explorer or a tool like MyPhoneExplorer it is located at /data/data/com.whatsapp/databases/

Install Android SDK

To save you from rooting and eventually bricking your device I suggest to download the Android SDK and spin up an emulated device. Typically they allow already root access.

Install and verify WhatsApp on emulated device

Then install WhatsApp on this emulated device and verify your phone number. The verification message will be send to your old Android phone.

Download decryption key from emulated phone

/data/data/com.whatsapp/files/key
If you have the adb drivers installed with your sdk installation, you can now execute some of the commands they have used in the Whatsapp Key Extractor with e.g. PowerShell or you can access your rooted device via command line. If you have the key, you can reverify your old Android WhatsApp if you like.

Decrypt Androids MsgStore.db.cryptXY

Just use the tool from Andreas Mausch together with your freshly extracted decryption key.

Whatsapp.ipa of the same version (google will help)

Downloading the Whatsapp.ipa does not need the real Whatsapp IPA file, but it is sufficient enough to download an alternative like Whatsapp++ extract it and find the Core Data folder WhatsAppChat.momd.

[friscoMad]

A fast and easy way to get the unencrypted DB is using the steps presented in this message:
https://forum.xda-developers.com/t/tool-whatsapp-key-db-extractor-crypt6-12-non-root-updated-october-2016.2770982/page-33#post-84264867
I am unsure if it does work in Mac but it was simple and worked almost at first try (I did not rename the downloaded apk as I should)

[shloak17107]

I suggest using the tool given in this repo: https://github.com/YuvrajRaghuvanshiS/WhatsApp-Key-Database-Extractor
The author and I spent the last couple of days getting it to work on macOS. It now works on macOS Big Sur with an Android 7.0 device

[residentsummer]

I'd like to thank you all for taking time and providing instructions for less experienced users. Added link to this issue to the README. 👏👏👏