Hardware Hacker Breaks the DRM on a The Bob Dishwasher

In what amounts to a very clever bit of hardware hacking, developer dekuNukem (the hacker who created a little device that automatically switches your screen to work when a boss walks by) has detailed a methodology for refilling the DRM-protected detergent cassettes for a $486 portable dishwasher called Bob.

Trust me, it’s more interesting than it sounds.

Bob is basically a small dishwasher that sits on your counter. It holds half a dozen dishes and some silverware, and you add water to the system by hand. It looks like a great alternative to a larger installed dishwasher or something nice for an apartment dweller. But it has a secret bit of DRM built in that keeps you wedded to the company’s products.

The Bob uses cassettes, called Rock and Pop (LOL!), that contain concentrated detergent and rinse liquids. The cassettes are similar to inkjet cartridges in that they store a small amount of information on a built-in chip—in this case, a simple I2C EEPROM that can store a small amount of information.

This chip stores the number of washes and will “cancel” a cassette when it’s technically empty. The machine will then order new cassettes automatically. To Bob’s credit, you can use your own detergent, but it isn’t easy. And the cassettes aren’t cheap.

“With shipping and VAT added, it costs a whopping £43 ($60) for 90 washes! That is 48p (67c) per wash. It might not sound like much, but it quickly adds up,” wrote dekuNukem. “Over a year of daily washes, it would have cost £174 ($242) in Bob cassettes alone! Imagine paying that much recurring cost for a dishwasher!”

Using an EEPROM reader, they were able to pull the data from the cassette and even modify it, resulting in a simple system to reset the cartridges back to their original wash counts or, in one case, forcing the cassette to run about 70 more washes than originally advertised.

Once dekuNukem figured out the coding mechanism, they had to figure out a way to refill the cassettes. They searched the internet for concentrated detergent offerings and found one that matched the website description exactly.

“Fortunately, all chemical products in UK comes with a Safety Data Sheet by regulation, which contains the composition and concentration of what’s inside. This way, I can compare an unknown detergent with Bob Cassette and get a rough idea of how close it is,” they wrote.

DekuNukem found a similar wash and rinse product, bought it, and squirted a bit into the cassette. Success!

The result? A 65-cent-per-wash cost savings.

“Refilling it yourself is more than 60 times cheaper, resulting in a massive 98% cost saving compared to buying new!” they wrote.

The plans and code for the open-source dishwasher DRM removal system are available on dekuNukem’s Github, and they’re actually selling the Cassette Rewinder, a pre-soldered board that will automatically reset the cassette EEPROM, for $29.99. Obviously, this isn’t great for the company that makes Bob, but it may make the product more interesting to the true anti-DRM zealots out there.