Messaging app Telegram may have lost its long-running privacy battle against the Russian government.

Russia’s Supreme Court has rejected an appeal made by the London-based Telegram Messenger LLP against a ruling that would force the app to hand its users’ encryption keys and chat histories over to the Federal Security Service or FSB, the country’s primary security agency.

Telegram tries to protect user privacy with end-to-end encryption, which gives each chat its own encryption key that is shared only between intended recipients. The company promises on its website that this method is extremely secure, saying, “There is no way for us or anybody else without direct access to your device to learn what content is being sent in those messages.” This promise will no longer be true if Russia’s security agency gains access to Telegram’s encryption keys.

The FSB, which was built from the remnants of Russia’s infamous KGB spy agency, claimed that Telegram had been used by a suicide bomber who killed 15 people in St. Petersburg last year. The court argued that the authorities would be able to protect citizens better if it could access Telegram’s user data.

However, this move could also put some Telegram users in serious risk, especially given reports that the FSB may be responsible for poisoning defectors or other people who have been critical of the Russian government and its leader, President Vladimir Putin.

Once a high-ranking KGB officer himself, Putin took direct control of the FSB in 2000 and has slowly expanded the agency’s scope to include counterterrorism, border security, intelligence monitoring and other state security roles.

Following today’s decision, the Russian court has given Telegram 15 days to turn over its encryption keys, after which the app may be blocked within the country. Despite pressure from the Russian government, however, Telegram Chief Executive Pavel Durov said on Twitter today that the company will continue to resist efforts to compromise its users’ privacy

“Threats to block Telegram unless it gives up private data of its users won’t bear fruit,” said Durov. “Telegram will stand for freedom and privacy.”

The government had already threatened to block Telegram last year, but the government relented when Durov agreed to register the company in Russia.

Photo: Yuri Yu. Samoilov via photopin cc