According to the paper “Bitcoin in Islamic Banking and Finance” by Charles W. Evans,

“The relationship between a distributed, autonomous Blockchain management systems (BMS) like Bitcoin—also referred to as a 'virtual currency'—and Islamic Banking and Finance (IBF). It shows that a BMS can conform with the prohibition of riba (usury)—as Bitcoin does—and incorporate the principles of maslaha (social benefits of positive externalities) and mutual risk-sharing (as opposed to risk-shifting). With regard to maslaha, the world's unbanked number in the billions and represent the majority of the world's adults.”

What is more Bitcoin may be more Halal than modern fiat money. Matthew (Blossom Finance, a fintech startup based in Indonesia.) puts it quite clearly as he remarks, “Bitcoin is more halal than any currency in wide circulation today but probably still falls short of the strict and narrow definition of money in Islam. Modern sovereign currencies are based on debt with usury - this is strictly prohibited in Islam. Therefore, all modern money is not halal. Bitcoin, on the other hand, is not based on debt - it's based on a proof of work - and this is at least not haram (impermissible).”