"They are looking for people who are now in this room.
You are their target, not because you are a terrorist, but because you have access to the system.
"You can access the private records of people's private lives, these are what they want," he warned . ".
Mr. Snowden has been living in Moscow, Russia, since he leaked documents on the scale and scope of global espionage by the National Security Agency and U. S. allies.
He is a wanted man in his native America.
But the IT expert, who signed a contract with the NSA and later became a whistleblower, insisted he wanted to return to the United States to face the court.
"I want to tell the jury why I did it.
I want to tell the court what these programs are.
"I want the jury to decide whether it is right or wrong for our rights and our constitution to be secretly violated," he told the audience . ".
But he is also pessimistic about a fair trial in the United States.
If convicted, he will face up to 30 years in prison.
Former Army intelligence officer and whistleblower Bradley Manning was sentenced to 35 years in prison for leaking US military documents in Afghanistan and Iraq.
"In the United States, I can't even enjoy a fair trial under the current law," Snowden said . ".
Snowden is popular in Germany because, under the leadership of the Nazi and Stasi secret police in East Germany, Snowden has a more negative view of government surveillance.
Read more: The German spy agency collects 0. 22 billion phone records per day
The report said that although German citizens may be opposed to large-scale surveillance, there was little sign of a major change in the corridor of the German spy agency after the Snowden incident.
Earlier this year, German foreign intelligence agency BND collected 0. 22 billion pieces of metadata daily from phone calls and text messages, according to German weekly Zeit.
Zeit also revealed that BND agents were instructed to be as elusive as possible when asked by the Supervisory Committee's politicians.
"A country like Germany has benefited the most from his [risk]Snowden]
"What was taken away was those who most shamefully abandoned him," Glenn Greenwald said at the meeting . ".
Snowden said he was still more optimistic "as usual" and said at the meeting that he would like to attend in person next year, but he would ask Chancellor Merkel first.
The American director of the Oscar-winning documentary Citizen Four tells the story of Snowden's revelation and how he went into exile. She says she lives and works in Berlin because she believes her material will be U. S. if she moves home
Internet security is one of the biggest problems with CeBIT 2015, and many startups are developing their own new security systems.
A recent study published by KPMG, the international auditing agency, shows that security awareness is becoming an issue that German companies are increasingly attaching great importance.
It also showed a sharp rise in cyber crime, from 26% of businesses said they were affected in 2013 to 40% in 2014.
Financial services are the most common target, but cyber criminals tend to target small and medium-sized companies because they have weak security systems.