Activists and dissidents worried about government surveillance learned long ago not to talk too freely on their home phone or mobile.
Landline and mobile systems offer repressive governments myriad ways to listen in, particularly when the systems are operated by state or state-linked companies.
But are Internet phone services -- which many regard as a safer alternative -- more secure?
Gregoire Pouget, an expert on digital security and privacy at Reporters Without Borders in Paris, says that might have been true once.
But today, he says, rights groups increasingly hear of people being imprisoned or sued based in part upon evidence from their online phone conversations.
"In Belarus and in Russia," Pouget says, "journalists told us that they have been caught with their Skype conversations."
Dangers Of Malware
Skype is by far the world's biggest Internet phone service provider, with an estimated 600 million users worldwide.
Pouget says one reason Internet phone services may be more vulnerable is the increasing availability of malevolent software programs -- called malware -- that target them.
"For a few hundred dollars, you can buy a malware and install it on the computers of those who are using Skype," he says. "You send it using an e-mail and if [the recipient clicks] on the attachment, then the malware is installed on the computer. And with this kind of malware, you can record the Skype conversations, the Skype chat typing, and you get all the contacts of someone using Skype."
The malware reverses the relationship that existed in many countries before the Arab Spring began in December 2010. During the Arab Spring, dissidents used the Internet to clandestinely organize mass street protests that caught their governments off guard and toppled regimes in Egypt, Tunisia, and Yemen.
Those events made activists in many countries regard the Internet as a safe zone just beyond their national governments' ability to oversee it. But now authoritarian governments also have realized the importance of the Internet and nothing can be taken for granted.
Open Letter To Skype
In an effort to alert both Skype and users to the dangers of increased surveillance, Reporters Without Borders and several other rights groups wrote an open letter to the Internet phone giant this month.
The letter urged Skype to make clear the level of confidentiality of conversations on its network. Skype's owner, Microsoft, has since told reporters it is studying the letter but has not publicly responded to it.
Sam Smith, a technologist at London-based Privacy International, says Skype used to be regarded as secure because in 2005 it issued a press statement assuring users that "nobody is listening in." But he says that since Microsoft bought Skype for $8.5 billion in 2011, the company has made no such public statements.
"What we very much need is some more certainty," Smith says. "Because in 2005, Skype said nobody is listening in, and when people started using Skype that was the main selling point. It was cheap, it was free, and it was also secure. If that has changed, the users of Skype deserve to know how and why so they can then make an informed decision."
While users wait for more information from Skype, some privacy experts recommend activists think more about how they communicate on the Internet.
"Maybe you should ask yourself, 'Do I really need to speak over the Internet?" Pouget says. "Isn't [text] chatting enough?' And if for you chatting is enough, you can try to use some very efficient alternatives that encrypt all that you are typing [as you] chat with someone else."
Privacy experts recommend that users pay particular attention to service providers' policies toward storing information and how they handle requests from authorities for access to stored information.
Smith of Privacy International says knowing those policies is important because if providers permit access to stored information, then even encrypted data can be easily searched.
How much authorities can demand access to data on the Internet, and under what circumstances, is one of the most contested issues between providers and governments today. The positions vary widely both among Internet companies and countries.