Paul Calder Le Roux, an admitted drug dealer with a background in encryption, planned to build a bitcoin miner had he beaten the rap.

In a last-ditch attempt to avoid incarceration, Le Roux wrote a letter to District Judge Ronnie Abrams, of the Southern District of New York (SDNY), this week detailing his personal history and addressing his alleged crimes. He was indicted on drug charges in 2012, pleaded guilty two years later and has been sitting in detention since. On Friday, he was reportedly sentenced to 25 years in prison, though he can appeal this decision.

Even if Le Roux wins an appeal, he would still face extradition to the Philippines, where he is wanted on a murder charge dating back to 2010. Should he be released by courts in both the U.S. and Philippines, however, he has planned his next step.

"I plan to start a business selling and hosting Bitcoin miners," he wrote in the letter to the judge filed June 11.

The letter provides some background on what bitcoin is and how it works, including how coins are mined through the use of ASICs, powerful chips designed for the task. Le Roux claimed he acquired related expertise working for the U.K. signals intelligence agency known as Government Communications Headquarters (GCHQ).

"I have a custom design for an ASIC chip that utilizes special optimizations in the underlying computer code or algorithm known as ('SHA'), I obtained this knowledge about the mathematical properties of SHA while working as a contract programmer at GCHQ in London in the early 2000's," Le Roux wrote.

"These optimizations have allowed me to create an ASIC chip design, and therefore ASIC miners, that are an order of magnitude faster at Bitcoin mining than any current design," he wrote. "To this end I plan to put my knowledge and skills to a better, and legal use."

The Bitcoin white paper was released in 2008 and the first coins were mined the following year. ASICs emerged a few years after.

Over recent years, speculation has abounded alleging that Le Roux might be, or have ties to, Satoshi Nakamoto, the pseudonymous creator of Bitcoin.

Last year, journalist Evan Ratliff published an article exploring this connection, based on a court filing by Ira Kleiman against self-proclaimed Satoshi Craig Wright.

"Paul Le Roux had the technical skills to create bitcoin – that much I’d concluded the first time around," Ratliff wrote.

Ratliff stops short of declaring outright that Le Roux is Satoshi, and notes there are many other programmers who fit the bill.

Le Roux does not appear to have claimed he is Satoshi, either.

He was sentenced to 25 years in an SDNY hearing Friday, according to Matthew Russell Lee of Inner City Press, who frequently posts updates from the courthouse.

Before the conviction was handed down, a prosecutor said Le Roux's plan to enter bitcoin mining "gives pause," though such a business "could be operated legally."

Le Roux cooperated with prosecutors, Lee reported.

Read Le Roux's full letter below: