Once thought impenetrable, there is a way to break the widely used Advanced Encryption Standard (AES), the encryption algorithm used to secure most all online transactions and wireless communications.
There is a way to attack that can recover an AES secret key from three to five times faster than previously thought possible, reported researchers at the Katholieke Universiteit Leuven, a research university based in Belgium and Microsoft.
The attack is complex is nature, and so it is not easy to carry out using existing technologies, researchers said. In practice, the methodology used by the researchers would take billions of years of computer time to break the AES algorithm, they said.
But the work, the result of a long-term cryptanalysis project, could be the first chink in the armor of the AES standard, previously considered unbreakable. When an encryption standard undergoes evaluation for vital jobs such as securing financial transactions, security experts judge the algorithm’s ability to withstand even the most extreme attacks. Today’s secure encryption method could be more easily broken by tomorrow’s faster computers, or by new techniques in number crunching. That is another perfect example, though, of why security measures need to undergo constant updating.
The National Institute of Standards and Technology (NIST) organization commissioned AES in 2001, to replace the DES Digital Encryption Standard (DES), which was then too fragile even as it provided adequate security for most everyday tasks.
With this work, the “safety margin” of AES continues to erode, said security expert Bruce Schneier. “Attacks always get better; they never get worse,” he said.
Though unwieldy to execute, the attack can apply to all versions of AES.
K.U. Leuven researcher Andrey Bogdanov, Microsoft Research’s Dmitry Khovratovich and Christian Rechberger from cole Normale Suprieure, Paris, completed the work. Both Bogdanov and Rechberger had taken leave from their respective universities to work on the project with Microsoft Research.
The creators of AES, Joan Daemen and Vincent Rijmen acknowledged the validity of the attack, according to K.U. Leuven.