New method makes it difficult to eavesdrop on phone calls

Scientists have invented a new method to encrypt telephone conversations that makes it very difficult to 'eavesdrop'.
Professor Lars Ramkilde Knudsen from Technical University of Denmark (DTU) has invented a new method called dynamic encryption to ensure that all telephone calls are encrypted and eavesdroppers are unable to decrypt information in order to obtain secrets.
"Today, all telephone conversations are encrypted - ie converted into gibberish - but they are not encrypted all the way from phone to phone, and if a third party has access to one of the telephone masts through which the call passes, they can listen in," said Knudsen.

"And even if the conversation is encrypted - in principle - it is still possible to decrypt it provided you have sufficient computer power," he said.
The vast majority of telecommunications operators use the same encryption algorithm - the so-called AES.
The new method expands the AES algorithm with several layers which are never the same.

"When my phone calls you up, it selects a system on which to encrypt the conversation. Technically speaking, it adds more components to the known algorithm. The next time I call you, it chooses a different system and some new components," said Knudsen.
"The clever thing about it is that your phone can decrypt the information without knowing which system you have chosen. It is as if the person you are communicating with is continually changing language and yet you still understand," he said.

Because any eavesdroppers would have to decipher the encryption key and encryption method - and both are thrown away by the phone after each call and replaced by a new combination - the conversation is extremely difficult to decrypt when dynamically encrypted.
The new system can prove hugely effective in combating industrial espionage, said Knudsen.
Industrial espionage occurs when different players discover and steal trade secrets such as business plans from companies, technical know-how and research results, budgets and secret plans using phone tapping.