Hacking my “smart” toothbrush (kuenzi.dev)

Article summary

The author reverse-engineered their Philips Sonicare toothbrush to understand how it communicates with the brush head, discovering that the head contains an NFC tag that tracks usage time. The tag is password-protected, but the author was able to extract the password by sniffing the communication between the toothbrush and the head. The password is unique to each brush head and is used to update the usage time counter. After three incorrect password attempts, the tag permanently disables write access, effectively locking out the user.

Main themes

• reverse engineering
• security features
• appliance design
• digital vs mechanical components
• repairability and simplicity
• engineer motivations and priorities

What commenters say

• Some commenters believe that the security features of the toothbrush are overly complex and unnecessary, while others think they are a reasonable measure to prevent tampering.
• The use of digital timers in appliances is seen as a potential source of unreliability and increased cost, while others argue that they can be more reliable and offer advantages over mechanical timers.
• The decision to add security features to a toothbrush is viewed by some as an example of engineers adding unnecessary complexity, while others see it as a legitimate attempt to prevent abuse.
• There is disagreement about the relative reliability of mechanical and digital components in appliances, with some arguing that digital components are more prone to failure and others claiming they can be more reliable if designed properly.
• Some commenters think that the focus on security and digital features in appliances comes at the expense of simplicity and repairability.
• The extraction of the password and the locking mechanism of the toothbrush are seen as a curiosity and a potential challenge to be overcome, rather than a serious security concern.