In an interview in Cointelegraph, Stallman said that while he was not against them, and was not campaigning to eliminate them, “I just don't particularly want to use them".

Stallman said that digital payment systems are fundamentally dangerous if they are not engineered to ensure privacy.

Countries like China which are thinking about bringing them in are the enemy of privacy.

“China shows what totalitarian surveillance is like. I consider that hell on earth. That's part of why I haven't used cryptocurrencies that are issued by the community. If the cryptocurrency is issued by a government, it would surveille people just the way credit cards do and PayPal does, and all those other systems meaning completely unacceptable."

Stallman said: "I don't do any kind of digital payments, and the reason is the systems that exist do not respect the user's privacy, and that includes Bitcoin. Every Bitcoin transaction is published."

Stallman was unconvinced about moves to make Bitcoin more private.

“The GNU project has developed something much better, which is GNU Taler. GNU Taler is not a cryptocurrency. It is not a currency at all. It is a payment system designed to be used for anonymous payments to businesses to buy something. It is anonymous through a blind signature for the payer. However, the payee must identify itself for every purchase in order to get money out of the system. So the idea is you can use your bank account to get Taler Tokens, and you can spend them and the payee won't be able to tell who you are.

“It won't be able to tell that you got the token from a particular bank account at a particular time, even though you did so. To convert your payment into money in its own bank, the store (the payee) will have to identify itself. So this gives privacy in a much more reliable way than cryptocurrencies do, and it blocks the idea of using this system to enable tax evasion.”

And in response to a question about Facebook's "Libra" digital currency project, Stallman says he hasn't study the details "because the most important thing about it I already know. It's connected with Facebook, and Facebook means surveillance.

"I urge people to join me in absolutely refusing to use Facebook or rather be used by Facebook. Because Facebook doesn't have users. Facebook has used. So don't be a sucker, don't be used by Facebook."