PAVEL DUROV is a reclusive online innovator who has repeatedly come up against the powers that be in Russia. In earlier years, on the social media platform VKontakte, he stood fast against demands from the Federal Security Service, known as the FSB, a successor to the KGB, to hand over the identity of users or to block certain protest groups. Mr. Durov also pioneered a popular messenger platform, Telegram, that is encrypted end to end, meaning government authorities can’t poke their nose into the messages. Now in self-­imposed exile, he is in the fight of his life against Russia and Iran. He should not give in.

The Russian communications regulator, Roskomnadzor, has been frantically trying to block the Internet Protocol addresses of Telegram after a Moscow court cleared the way because Telegram refused to give the authorities access to its users’ messages. In pursuit of Telegram, the regulator has blocked, at times, more than 18 million IP addresses — including those of overseas cloud services hosted by Google and Amazon — creating havoc for Russian businesses. (Jeffrey P. Bezos, founder and chief executive of Amazon, owns The Post.) The tactic has been costly for Telegram in terms of reduced capability, but not fatal. By moving around, Mr. Durov has managed to keep Telegram alive for Russians. On Monday, several thousand protesters, mostly young people, demonstrated in Moscow against the attempted blockage, some carrying signs such as “Don’t Block On Me” and throwing paper airplanes, which are Telegram’s symbol. On the same day, Iran’s judiciary banned Telegram because authorities believe it was used to organize protest rallies in January.

This is a battle for Internet freedom worth waging. If Russia succeeds at shutting down Telegram, then it may well make similar demands of Facebook and Google, among others. So far, the effort by Roskomnadzor to silence Telegram has appeared to be technically sloppy, failing to effectively shut it down, while damaging legitimate Russian businesses that need unfettered access to the Internet. It would be nice if Roskomnadzor would just admit defeat and abandon the campaign. More likely, the agency will learn from this experience and emerge more proficient at Internet censorship than it was before — more like China.

This is not Russia’s first attempt to block something on the Internet, but it is more systematic and sweeping than before. Mr. Durov deserves praise for once again standing up to Big Brother. By striving to keep Telegram online, he is showing the kind of backbone we wish would be emulated by others in the digital universe who too often give in to the demands of authoritarian regimes for control over messages and data.

What’s really at stake in the battle over Telegram? More than just the future of one messenger service. If Russia, China and Iran can successfully cordon off hundreds of millions of users, they diminish freedom everywhere. Those who cherish liberty ought to be rooting for Mr. Durov.

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