Bitcoin aficionados have long wanted to prove the virtual currency is a good replacement for old-school cash.

What better time to press the issue than now, when world governments including Greece and Argentina have struggled to keep their financial systems from collapsing?

Greece is the site of the latest Bitcoin gold rush. (If you can fairly compare a digital currency to shiny rocks pulled from the earth, that is). U.K. company Cubits has partnered with Greek bitcoin exchange BTCGreece to launch a service that lets Greek merchants use bitcoin to pay the foreign companies that send them supplies.

The joint company, called Cubits.gr and based in Athens, also plans to introduce 1,000 bitcoin ATM machines throughout Greece starting as early as October. The country now has four of the ATMs, three of which were set up last month.

The house of bitcoin in Paris. Bitcoin is getting modest traction in Europe.

The purpose of the ATMs: bypassing the strict financial laws known as "capital controls" that restrict the flow of money to go outside Greece.

Bitcoin, a six-year-old digital currency known for its volatility, is not tied to any government or central bank. Because it is unregulated, monetary authorities have no control over its use. People can transfer it, even across borders, with the touch of a smartphone.

But it won't be easy to get traction, at least at first. Bitcoin adoption in Greece — a society that operates largely in cash and avoids even credit cards— is low, with fewer than 10,000 users, according to BTCGreece founder Thanos Marinos, the managing director of Cubits.gr. Less than half are regular users.

But interest in bitcoin has shot up all across the eurozone in recent months. San Francisco-based bitcoin payments processor Coinbase saw a 350% increase in signups the week after Greece's July 5 referendum, said Adam White, vice president of business development and strategy.

In Greece, signups for BTCGreece rose from one or two daily a year ago to 150 daily this summer, Marinos said.

Cubits.gr is the second company to use bitcoin and its blockchain technology to capitalize on Greek citizens' growing distrust in traditional financial institutions.

Earlier this summer, Irish startup Spartan Route also began using bitcoin to facilitate both imports and exports for Greek firms. For Greek companies exporting goods abroad, Spartan Route invoices the foreign firm in euros, then delivers the funds to the Greek company in bitcoin.

The Bitcoin window comes just when Greece is still sick of thinking about where to get cash. Following a three-week bank holiday in July, Greece has gradually loosened restrictions on ATM withdrawals, foreign bank transfers and payments abroad. Greek citizens were previously restricted to withdrawing 60 euros per day; now they can take out 420 euros per week at once. Until last month, companies were unable to send even tiny amounts of money abroad to pay for services like web and domain hosting. Greece has now eased some restrictions.

The machines will allow people to exchange their euros for bitcoins and bitcoins for euros.

"At the moment, almost everything related to payments outside Greece is on hold," said Marinos. "Bitcoin is an immediate solution that will bring the economy to a better standard."

In the U.S. bitcoin is so prevalent that it's even available in gun stores. Now entrepreneurs have their eyes set on weaker economies. Image: Eric Gay/Associated Press

Greece's capital controls, implemented on June 29 to prevent a banking system collapse, have wreaked havoc on an already troubled economy.

Limits on foreign bank transfers have made it difficult or impossible for businesses that rely on imports to pay their suppliers abroad. About 65% of Greek goods are imported.

For now, the Bitcoin ATMs are perfectly legal: Greece does not consider bitcoin a currency or commodity.

Cubits, which is based in London, sees 1,000 signups per week for its virtual bitcoin wallets, according to its website.

Left-wing Syriza party leader Alexis Tsipras, left, and leader of the right-wing Independent Greeks party Panos Kammenos raise their hands as they greet supporters in Athens, Sunday, Sept. 20, 2015. Image: Lefteris Pitarakis/Associated Press

Cubits' new affiliate in Greece, Cubits.gr, acts as an intermediary between Greek companies and their foreign suppliers and business partners. To use it, a Greek merchant uploads their invoice to Cubits.gr's system and deposits the amount they would like to send abroad. Cubits.gr converts the money into bitcoin to transfer it outside Greece, then converts it again into whatever currency the supplier needs to be paid in.

Greek merchants do not necessarily need to buy bitcoin in order to use the service, nor do foreign companies need to accept bitcoin to receive the payment.

"We made it easier for them," Marinos said. The company collects a small fee per transaction. It will focus on small to mid-sized Greek enterprises in the e-commerce, tourism and import/export industries.

Some money is more equal than others

As of this week, Greek citizens can send up to 500 euros out of the country each month. The eased rules also make it easier for businesses to transfer money abroad. But most business transactions still require permission from special foreign transactions committees within the Greek banks.

Each bank has a different daily transaction limit. Items deemed essential to daily life — such as medicine, food, raw materials and anything related to energy — get higher priority. Businesses trying to pay for anything else must cross their fingers and hope there's enough wiggle room in their bank's transaction limit that day.

A stock exchange employee sits under a ticker showing share prices in Athens, on Monday, Sept. 21, 2015.

That system, while restoring the economy to a minimum level of function, has created a backlog of transaction requests among companies whose payments are deemed nonessential. It has affected primarily small and mid-sized Greek companies that don't have a foreign bank account or foreign parent company to make payments for them.

Taki Maskell of MadinMedia, an Athens-based interactive marketing agency, said it's been difficult to pay for everything from the company's web host to foreign suppliers of the audiovisual equipment he needs for clients' advertising campaigns.

"Maybe it's not as essential as food, but it's definitely essential for a company like ours," Maskell said.

Complicating matters further, since June his domestic suppliers have been demanding payment up front — in cash — rather than extending lines of credit because they want liquidity themselves.

That led MadinMedia to look for payment alternatives. They participated in early demonstrations of Cubits.gr and plan to use the service.

But given the lack of regulation around bitcoin in Greece, Maskell is cautiously optimistic.

"What we're discussing here could be stopped in a couple of months," Maskell said, adding that he hopes the industry can show Greek regulators how bitcoin "can work for them rather than against them."

Getting paid for exports in bitcoin helps companies avoid the strict financial laws in place because the digital currency is not subject to government restrictions, said Spartan Route's chief operations officer Danny O'Donovan. But so far it's been a hard sell to Greek merchants unfamiliar with the digital currency.

BitPagos, the biggest bitcoin company in Argentina, is also looking to set up shop in Greece. The two-year-old startup allows merchants — primarily from the hotel and tourism industries — to bill their customers in bitcoin or dollars, bypassing the country's own capital controls and troubled Argentinian peso. BitPagos processes more than $700,000 in bitcoin payments monthly.

If bitcoin can catch on in Argentina, it can also gain traction in Greece, said BitPagos CEO Sebastian Serrano. At least 60% of Latin Americans don't even have a bank account, according to several surveys, but many use bitcoin because all they need to access it is a smartphone.

"When banks fail, people start losing trust in them and stay away," Serrano said. "If that trust is broken, like what happened in Argentina and in Greece, it makes people think about what alternatives exist."