Former head of US Homeland Security warns building backdoors into encryption would be 'a mistake'

Michael Chertoff argues preventing criminals communicating is 'a pipe dream' and backdoors would just make ordinary users less secure

A former senior US security official has spoken out against the potential of government being able to request backdoors into encrypted applications.

Speaking at the Aspen Security Forum, former head of the Department of Homeland Security and former federal prosecutor Michael Chertoff warned it would be a mistake to require companies to make unencrypted communications available to government on request.

Organisations including Facebook, WhatsApp and Snapchat have found themselves in the firing line of UK and US governments that argue that they should be able to access these communications in order to fight crime and terrorism.

For example, British Prime Minister David Cameron used the Charlie Hebdo attack to call for greater government surveillance powers.

However, Chertoff, who served as United States Secretary of Homeland Security under President George W Bush, was critical of plans to require companies to build cryptographic backdoors into their products.

"I think that it's a mistake to require companies that are making hardware and software to build a duplicate key or a backdoor even if you hedge it with the notion that there's going to be a court order," he explained.

"When you do require a duplicate key or some other form of backdoor, there is an increased risk and increased vulnerability. You can manage that to some extent. But it does prevent you from certain kinds of encryption. So you're basically making things less secure for ordinary people," he said.

Chertoff also argued that no matter what government does in an attempt to restrict the communications of criminals, those intent on hiding their communications from the authorities will continue to find ways to do so.

"The really bad people are going to find apps and tools that are going to allow them to encrypt everything without a backdoor. These apps are multiplying all the time," he explained.

"The idea that you're going to be able to stop this, particularly given the global environment, I think is a pipe dream," Chertoff continued. "So what would wind up happening is people who are legitimate actors will be taking somewhat less secure communications and the bad guys will still not be able to be decrypted.

"I think requiring people to build a vulnerability may be a strategic mistake," he concluded.

Chertoff isn't the only high profile individual to have criticised government plans to introduce backdoor surveillance measures in order to make all communications easily accessible by police and intelligence agencies.

A group of the world's foremost computer science and cryptography experts recently released a report that condemned plans by UK and US governments as unworkable and potentially harmful to the functioning of the entire internet.

Dr Ann Cavoukian, former information and privacy commissioner of Ontario, Canada, who developed the concept of Privacy by Design, believes Cameron's proposals in particular are concerning.

"I'm worried because you can't predict which direction it is going to go in; it could cause enormous harm," she said. "He's listening to policy people and lawyers but he's not listening to the technologists."