AES mais fraco do que se pensava

Has the advanced encryption standard been broken or weakened?

Research emerged last week that claimed that the Advanced Encryption Standard (AES) was ‘broken'.
The cryptanalysis project, carried out by Andrey Bogdanov (from the Katholieke Universiteit Leuven in Belgium, visiting Microsoft Research at the time of obtaining the results), Dmitry Khovratovich (Microsoft Research) and Christian Rechberger (ENS Paris, visiting Microsoft Research) found a ‘clever' new attack that can recover a secret key four times more easily than originally anticipated by experts.

According to the research, weaknesses were identified in 2009 when AES was used to encrypt data under four keys that are related in a way controlled by an attacker. It found that while this attack was more intriguing from a mathematical point of view, what was interesting was that the attack applies to all versions of AES even if it used with a single key.

The research also claimed that finding an AES key is four times easier than previously believed, yet the effort to recover a key is still huge: the number of steps to find the key for AES-128 is an eight followed by 37 zeroes.

It said: “To put this into perspective: on a trillion machines that each could test a billion keys per second, it would take more than two billion years to recover an AES-128 key.”

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