Advanced Encryption Standard (AES)

The Advanced Encryption Standard (AES) is defined as a symmetric-key encryption standard adopted by the U.S. government.

Assuming that you have access to 10,000 up-to-date PCs and stating any other reasonable assumptions you need to make, calculate how long it will take, on average, to derive an AES key using a key space search (sometimes referred to as a brute force attack).

Solution:

·         1 Gigahertz (GHz) = 1,000,000,000 cycles per second

·         AES can support 128 bits, 192 bits and 256 bits key sizes

·         Using brute-force approach = 3.4 x 10³⁸

·         Each PC can process 2,600,000 cycles per second

·         10 = 10 cycles

Then:

1 PC:              2,600,000,000/10 = 260,000,000

10 PCs:          260,000,000(10,000) = 2.6x10¹²

AES key:                    (3.4 x 10³⁸) / (2.6 x 10¹²) = 1.3 x 10²⁶ seconds

                                                            = 3.6 x 10²² hours

Algebraic Aspects of the Advanced Encryption StandardAdvanced Encryption Standard - AES: 4th International Conference, AES 2004, Bonn, Germany, May 10-12, 2004, Revised Selected and Invited Papers