President Dilma Rousseff posted a series of tweets over the weekend, saying the move was required to "prevent possible espionage¹".

 

She added the country's Federal Data Processing Service (Serpro) would be charged with developing the system.

 

One expert said the tech involved was well established but had limitations.

 

"There's a good precedent²（先例） for this with the German provider Gmx.de," said Prof Ross Anderson, head of the security research group at the University of Cambridge's computer laboratory.

 

"They just need to tell a company to keep the servers in Brazil, encrypt all the traffic inside or outside the country, and only give access to Brazilian police and intelligence services.

 

"Bang, finished, it's trivial. It's a well understood and well solved problem."

 

He said that the Brazilian system could be designed to interact with Gmx and equivalent encrypted services, in which case the NSA (US National Security Agency) and GCHQ (UK Government Communications Headquarters) would effectively be shut out unless the countries where the relevant servers were based decided³ to co-operate.

 

But he added that information could still be intercepted⁴ if cyber-spies were able to install malware on their target's computers or if users corresponded with someone using an non-secure email service.

 

"From the point of view of people writing to each other in Brazil, they have some protection against foreign snooping, however more and more business these days is done internationally," he said.

 

"With Gmail having something like a third of all email traffic worldwide, that means the Americans will still be able to read an awful lot of messages.

 

"If you have an email [copied] to a dozen different people there will be a fair chance one of them will be using Google's service."

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