Moscow:
Leading encrypted apps recommended by the Islamic State group for secure messaging said on Thursday they were making modest moves to stop jihadists using their technology in the wake of the bloody attacks in Paris, but defended a right to privacy.
Instant messaging app Telegram, created by Russian Internet guru Pavel Durov, said it had blocked dozens of accounts associated with IS that were reportedly being used to spread extremist propaganda.
Meanwhile, the encrypted communications firm Silent Circle said it was tightening access to its mobile apps and secure smartphone to make them harder for terrorists and criminals to use.
The moves come as pressure builds on new messaging services to balance their obligations to users against security concerns following the deadly attacks in Paris and the recent downing of a Russian plane in Egypt, despite there being no evidence the attackers used these systems to communicate.
Telegram, a free app which was launched in 2013, says it "provides a secure means of communications everywhere on the planet" and blasts Internet giants Facebook and Google on its website for giving private data to third parties.
It offers an encrypted chat service with self-destructing messages and has recently launched a way to create public channels to broadcast to unlimited audiences.
According to the Middle East Media Research Institute (MEMRI), the technology is fast becoming popular among jihadi groups, with IS and Al-Qaeda groups creating several channels.
"We were disturbed to learn that Telegram's public channels were being used by ISIS to spread their propaganda," the service said on its own Twitter account late Wednesday.
"As a result, this week alone we blocked 78 ISIS-related channels across 12 languages," it added, saying it relied on user reports to find the channels.
Telegram's Durov, however, specified that the "only publicly available channels could be reported and blocked" and denied that he can intercept conversations.
Meanwhile Silent Circle -- the Swiss-based firm which makes the encrypted Blackphone handset and Silent Phone applications for private messaging -- said they were "enacting more aggressive back-end payment technology to reduce the likelihood of evildoers" like IS using the service.
"Since ISIS labeled us as the strongest product, we are going to implement what we feel is responsible and morally acceptable procedures to make it harder for the bad element to get our technology," Mike Janke, the company's co-founder and chief executive, told AFP.
'Privacy more important'Encryption of communications surged after fugitive ex-NSA employee Edward Snowden revealed in 2013 the massive data harvesting done by US agencies.
Telegram quickly amassed a following. While the precise number of users is unknown, in August the company said it is used to send 10 billion messages every day.
In the aftermath of the attacks however it could become harder for encrypted apps to defend their policy, as governments are likely to push for restrictions on the technology so it can better carry out surveillance of extremist groups.
Britain earlier this month published draft legislation that would give security officials access to Internet communication records of suspects.
In the aftermath of the Paris attacks, intelligence chiefs including CIA Director John Brennan have raised the alarm about unpierceable messaging applications.
However the Swiss-based Threema, another application that offers an encrypted messaging app that IS has recommended to its followers as a secure communications channel, warned against allowing a return to "total surveillence" which has never worked in the past.
"Sacrificing some of the very foundations of our western democracies -- liberty, privacy and freedom of speech -- for a false sense of security does not seem like a smart thing to do," said Threema spokesman Roman Flepp.
He said the company would cooperate with Swiss authorities if legally required to, but that the company did have access to keys clients use to encrypt communications.
Durov has previously admitted that IS jihadists use his network but stood by his policy to keep conversations private.
"I think that privacy, and our right for privacy, is more important than our fear of bad things happening, like terrorism," he said at a conference organised by TechCrunch in late September.
"Ultimately, ISIS will always find a way to communicate among themselves," Durov said when asked how he sleeps at night knowing IS uses his product.