The scientist behind the world’s most popular computer programming language says he regrets that his greatest work was used to build Bitcoin, before labelling the cryptocurrency as a tool for criminals.

Danish computing legend Bjarne Stroustrup invented the C++ language 34 years ago. Since 1985, it has remained the most commonly used global code and is integral to almost every digital system in the world.

Now, however, Stroustrup has revealed his biggest regret over the last four decades is that his work went on to become the code upon which Bitcoin was based.

“When you build a tool, you do not know how it is going to be used,” he lamented.

“I’m very happy and proud of some of the things C++ is being used for and there are some other things I wish people wouldn’t do.

“Bitcoin mining is my favourite example – it uses as much energy as Switzerland and mostly serves criminals.”

The 68-year-old – currently a managing director at Morgan Stanley in New York – has spoken before about his disdain for cryptocurrency, but this is the first time he has expressed remorse over his code being associated with BTC.

Regrets

Speaking on the popular Lex Fridman podcast, the University of Cambridge Churchill College graduate enthused over the great achievements made with computer science, but he turned his guns on Bitcoin while discussing regrets as he highlighted his deep concern for environmental issues and criminality.

Half of all Bitcoin transactions have, according to a handful of studies, links to criminal activity in some form or other. It has also been suggested that almost a quarter of BTC users are also involved in illegal activity to the tune of $72 billion a year.

Bitcoin also attracts criticism for its negative environmental impact, using up a mind-boggling seven gigawatts of electricity a year and accounting for 0.21% of the world’s supplies.