White supremacists and neo-Nazis aren't shy in their support for bitcoin, a digital currency that aims to sidestep banks and governments. It's these same characteristics that have made bitcoin a fixture of the online drug trade.

PayPal and Apple Pay both recently barred some prominent hate-peddlers from their platforms, making it difficult for fascists to solicit donations. For them, bitcoin is an alternative. Richard Spencer tweeted in March that bitcoin was the "currency of the alt right." The neo-Nazi website the Daily Stormer has been following bitcoin for years, and in January the site's founder, Andrew Anglin, called bitcoin the "Nazi cryptocurrency" in an article on the site. Notorious hacker and racist Andrew Auernheimer, who goes by "weev" and has Nazi imagery tattooed on his body, has also expressed his support for bitcoin.

Read More: Following Other Tech Companies, Cloudflare Has Dropped the Daily Stormer as a Customer

With several tech companies kicking neo-Nazis off of their platforms in the last week, it's a good time to ask: Could bitcoiners do anything to stop these people from using the tech, if they wanted to?

Motherboard looked at the bitcoin donation addresses of several prominent neo-Nazis and white supremacists, as well as their organizations, including the Daily Stormer, Stormfront, Auernheimer, Anglin, and Christopher Cantwell (who was recently filmed by VICE News saying he would "kill" protesters in Charlottesville "if we have to"). These addresses, since 2014, have altogether been sent more than $1 million USD worth of bitcoin at today's prices, around $4300 per whole coin. However, at the time of writing, these accounts contain much less than that amount: $71,742 altogether, with Auernheimer holding the lion's share. Still, transaction records show donations are still coming in. The Daily Stormer has received roughly $5,000 in bitcoin since Monday.

So, what can conscientious people in bitcoin do to stymie the use of the technology by neo-Nazis? Bitcoin is a technology, not a company, but companies that act as intermediaries for bitcoin transactions can take action against neo-Nazis, and may have done so already. On Tuesday, a Daily Stormer supporter claimed on Twitter that Coinbase, a bitcoin exchange that operates a wallet service, deleted their account for donating to the neo-Nazi site.

When contacted by Motherboard, Coinbase would not comment on individual accounts, but said in an emailed statement that it actively seeks out customers who use the service to promote violence and closes their accounts.

"Coinbase prohibits use of an account which would abuse, harass, threaten, or promote violence against others," the emailed statement said. "Coinbase continues to take action to enforce this policy across our platform, including to restrict access to Coinbase services and to close accounts."

Companies like Coinbase can act as a bottleneck for neo-Nazis. This is because, simply, it controls their bitcoin wallets. Even though bitcoin users are identified on the system's public ledger only by strings of numbers and letters, exchanges often comply with US Know Your Customer (KYC) regulations. These policies require customers to identify themselves, which makes it possible to attach an identity to bitcoin transactions. Coinbase enforces KYC, which may allow it to identify people promoting violence.