Enlarge (credit: US Marine Corps)

Nicholas Weaver made no bones about it: he really, really dislikes cryptocurrencies.

Speaking at the Enigma security conference in Burlingame, California, last week, the researcher at UC Berkeley’s International Computer Science Institute characterized bitcoin and its many follow-on digital currencies as energy-sucking leeches with no redeeming qualities. Their chief, if not only, function, he said, is to fund ransomware campaigns, online drug bazaars, and other criminal enterprises.

Meanwhile, Weaver said, there’s no basis for the promises that cryptocurrencies’ decentralized structure and blockchain basis will fundamentally transform commerce or economics. That means the sky-high valuations spawned by those false promises are completely unjustified. He also said investors’ irrational exuberance just adds to the unviability of cryptocurrency.