The jailbreak is located here:
https://www.mobileread.com/forums/sho...d.php?t=186645
The fonts hack for the Kindle Touch and both Paperwhites is here:
https://www.mobileread.com/forums/sho...d.php?t=219405
But the fonts hack specifically is somewhat complex, be careful you understand what you are doing and make sure you install the linked rescue pack in case of emergencies.