LONDON - A pro-independence group in Spain's Catalonia region is using a smartphone app to outwit authorities, as it steps up demonstrations following the jailing of several of the movement’s leaders.



The group Democratic Tsunami released the app to coordinate demonstrations across the region.

The latest target was the world-famous El Clasico soccer match between Barcelona and Real Madrid on Dec. 18. There were violent clashes outside the stadium, and protesters disrupted the game by throwing balls bearing pro-independence slogans onto the field.

Democratic Tsunami has no apparent leader and those behind it are anonymous. In recent weeks, the group has mobilized thousands of demonstrators in minutes, catching authorities by surprise.

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“It is decentralized in the sense that you can’t identify who is sending the notifications for the protests,” said professor Enric Lujan, a political scientist at the University of Barcelona.

“They developed it that way. The app has that architecture in order to avoid the authorities from knowing who is behind Tsunami Democratic, which is the main obsession, for example, of the Spanish Interior Ministry.”



Lujan said the Democratic Tsunami app takes special steps to remain anonymous.



“You cannot download it from the usual channels such as the Google Play Store or the iPhone App store. You have to look for a link and then download the app directly,” he said.



Even after the app has been downloaded, it still needs to be activated by another approved user, explained software engineer Silvia Puglisi of the Polytechnic University of Catalonia.



"You just go to a protest, and you exchange a QR code. The QR code is a cryptographic key, and once the keys are exchanged, you are part of the system."



Democratic Tsunami has grown rapidly in the space of a few months, staging protests that have paralyzed Barcelona’s airport and the main highway to the French border. Spain’s National Court has ordered the Democratic Tsunami website to be shut down, citing possible terrorism offenses. Madrid jailed nine Catalan independence leaders in October on charges of sedition.



The political party Pirates of Catalonia has taken the fight to the European Union’s Court of Justice, claiming the terrorism investigation is an abuse of basic human rights.



Experts say that if the coding is made available, the app could be used by other protest movements, like pro-democracy demonstrations in Hong Kong.



"The idea is to just exchange a key. You don’t exchange any other information, and it’s totally decentralized. There is no central service, and you just communicate with your friends on a peer-to-peer basis,” Puglisi said.



There are concerns that with no oversight from a regulated app store, the Democratic Tsunami app could break strict European rules on storing and sharing data, such as the tracking of its users’ movements.



Supporters say it’s a vital tool in the face of what they claim is an attempt to stifle basic freedoms.

