One Ukrainian group called Come Back Alive, for instance, has raised $200,000 for Ukrainian troops in just the second half of 2021, according to Elliptic. The group originally solicited donations for military equipment like bulletproof vests, but it has since expanded into funding the purchase of reconnaissance and targeting systems.

The disadvantage of cryptocurrency, of course, is that in some respects it's even less private than the traditional banking system—as Elliptic's own ability to track the Ukrainian groups' donations through blockchain analysis shows.

Elliptic says that each of the recipients named in its analysis had publicly posted cryptocurrency addresses to receive donations—addresses that rarely changed, or didn't change at all in some cases. That sort of "static address" makes cryptocurrency tracing trivial, compared to cases in which the recipient generates a new address to every donor.

Gladstein also points out that privacy likely isn't the priority for organizations that are potentially fighting for survival. Aside from Ukraine, he points to Belarusians' struggles with the country's pro-Russian dictatorship, in which millions of dollars in bitcoin donations have helped keep striking workers afloat. "It's really been a lifeline for the resistance," Gladstein says.