Worried your government is going to take your savings? There’s an app for that.

Actually, there’s an entire currency: Bitcoin, an online-only currency based on a decentralized network. It’s unregulated, hard to track and increasingly common. Since Sunday, downloads of three Bitcoin-related apps have surged on Spanish charts, Bloomberg Businessweek reports.

The interest in Bitcoin coincided with news that the Cyprus government planned to tax savings accounts as part of the country’s bailout program. The value of the online currency increased more than 20 percent in the past two days to $64, according to the latest price information.

The downside is it’s a currency that has experienced price fluctuations, occasional hacking and account thefts, and is a favorite for black-market transactions, including almost 2 million a month in illegal online drug purchases at the Silk Road marketplace. That some Europeans are investing savings in Bitcoin isn’t exactly a sign of confidence in European banking.

According to a European Central Bank report published in October, increased demand for Bitcoin “could have a negative impact on the reputation of central banks,” especially if the public perceives Bitcoin’s rise is due to “a central bank not doing its job properly.”