For starters, it does not allow cloud backup which means all the backups are stored locally on your smartphone storage.
To make chat backups more secure, Signal also encrypts the backup file with a passphrase. Users need to enter the passphrase to restore the backup.
Here’s how to take chat backup on Signal.
Open Signal app and head to Settings
Then tap on Chats and media and select the option Chat backups
Tap on Turn on button
Then tap on Choose Folder button from the popup
Select an existing folder or create a new folder
Tap Use this Folder button and allow necessary permissions
Now, note down the passphrase for your backup file
Do note that this passphrase is mandatory to restore the backup in future.
Check the disclaimer checkbox and tap Enable Backups
To take the backup, tap Create backup option
How to restore a backup on Signal
To this, install a fresh copy of Signal on your smartphone. Verify your phone number and select Restore.
Select the file stored on your smartphone and enter the passphrase to verify and restore the backup.