21 Inc has applied for a patent for specialized bitcoin mining circuitry, public records show.

According to an application published earlier this month by the US Patent and Trademark Office (USPTO), 21 Inc is seeking a patent for “digital currency mining circuitry with adaptable difficulty compare capabilities”.

The application was originally filed on 6th May, 2015, with 21 co-founders Nigel Drego, Veerbhan Kheterpal and Daniel Firu named as inventors. The application is the second for 21, which submitted a similar application in April 2014 that was published in October of last year.

Bitcoin mining is an energy-intensive process by which entities on the network race to create the next valid block of transactions, and the successful addition of a block nets the miner 12.5 fresh bitcoins, worth roughly $9,200 at current prices. In the years since bitcoin’s creation, mining has evolved from smaller, home-based setups to data center-based operations that run hundreds of machines simultaneously.

According to the application, it’s the rise of specialized bitcoin mining hardware that resulted in a need to develop improved methods for chasing the next block.

The application states:

“The difficulty of the cryptographic puzzle has led to the use of dedicated circuitry designed specifically for bitcoin mining. Such dedicated circuitry can be expensive to design, purchase, and operate. It may therefore be desirable to provide improved systems and methods for performing cryptographic operations and for verifying the solutions generated from the cryptographic operations.”

The filing is notable given that 21 Inc had worked with Intel on the development of a bitcoin mine that began operating in 2013, using chips from the Santa Clara-based technology firm as detailed in documents obtained by CoinDesk last year.

21 has gone on to build its strategy around the Bitcoin Computer released in September 2015 and aimed at creating a basis for machine-to-machine payments using the digital currency. The startup, which has raised more than $100m in venture funding to date, launched a software suite in May as part of a push to expand the concept to other devices.

The USPTO has published a number of bitcoin and blockchain patents in recent weeks, including those from startups Blockstream and Digital Asset Holdings, as well as established firms like AT&T and Nasdaq.

21 did not respond to requests for comment.

Image via Shutterstock