Google is facing calls to lift a block it has placed on its services for Iranian users as the regime continues to clamp down on protests in the country.
The use of counter-censorship technology is increasing in Iran after the authorities blocked access to popular communications services amid continuing demonstrations against the regime.
Despite president Hassan Rouhani claiming he would allow "space for legal criticism" of the regime, the Iranian government has continued to clamp down on its citizens' internet communications.
:: At least 21 people killed in Iranian protests
Iran's government has responded to protests by blocking apps and circumvention tools, but harder to get a sense of what's happening to the core Internet infrastructure. So maybe people inside running speed tests, it's throwing the sample of my data source! pic.twitter.com/8iVfkHoW3l
— Collin Anderson (@CDA) January 2, 2018
Although data is only available on a two-day delay, the number of Iranians using the Tor anonymity network has surged to over 10,000 at the last count.
International support for the protesters has been voiced by Donald Trump, but US sanctions against Iran may be responsible for preventing Iranians from bypassing the regime's blocks.
Speaking to Sky News, Dr Steven Murdoch noted how alongside anonymity network Tor, the instant messaging app Signal was designed to bypass blocking by disguising itself amongst Google's services.
"This technique has been deployed in Egypt and UAE," said Dr Murdoch. "However as a result of US sanctions, Google blocks users from Iran from accessing many of its services, including the one that Signal uses to resist blocking."
Collin Anderson, a researcher on Internet infrastructure and expert on Iran, has identified the service as Google App Engine (GAE), a cloud computing platform which Signal uses to conceal its traffic from anyone conducting network surveillance.
Citing Mr Anderson's work, the NSA whistleblower Edward Snowden challenged a number of American politicians to call Google to "restore millions of protesters' ability to connect and organise".
Google may be concerned that Iranian nuclear scientists will register a free account on GAE to run physics simulations as part of prohibited nuclear research.
"As I understand Google seems to believe that GAE is subject to supercomputing export controls, and therefore really off limits to Iran," wrote Mr Anderson. "But it's much more aligned with cloud services, which are possibly exempted [from the sanctions]."
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"Google could whitelist (allow) Signal and Tor, and incur basically no sanctions liabilities. And civil society has been writing and meeting with Google about GAE since 2013," Mr Anderson wrote.
Google has not responded to media enquiries regarding the blocks.
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