The Advanced Encryption Standard - Admission/Application Essay Example

In 2001, NIST made AES the Federal Information Processing Standard, FIPS, for the United States federal government (Pachori et al, 967). AES is actually a variant of Rijndael cipher where there is a fixed block range of 128 bits and the keys for the AES vary from 128, 192 to 256 bits. AES is usually known by the key size that is used in its package, i.e., AES-128 or AES-256. Contrary to the AES, Rijndael cipher is any block or any key size that is in multiples of 32 bits (Paar & Pelzl, 2010).

AES encryption requires the data being flattened into a 4 x 4 column-major order matrix and it has a special finite field in which the calculation is done. The design principle used for the AES is the substitution-permutation network which is several times faster than the Feistal network used by the DES.The transformation of the input data is done in a number of cycles called the repetition. These repetitions are a specified number for the type of the key size that is being use to convert the data from the input text called the plaintext to the output text called the ciphertext.

The cycles of repetitions for the key sizes 128, 192 and 256 are 10, 12 and 14 respectively. Each cycle contains several steps in which the one of the stage is actually dependent on the encryption key itself due to which only the key can be used to decrypt the cipher text. All these steps are applied in reverse in order to transform the ciphertext back into plaintext (Martin, 126). AES, however simplistic in its description, is a very strong encryption standard which actually enables the general populace along with many companies that specialize in the security services to use it for data protection.

Strength of AES lies in the size of the encryption key as opposed to the design that is used for the encryption. So security of the key is a must because if the key is somehow retrievable via hacking, the whole process of the encryption is actually worthless to the cause. So its strength is primarily valuated on the time it would take a brute force attack to find the encryption key out of the possible combinations. The longer the key that is used to encrypt the plaintext, exponentially longer is the time required to crack the key used in the encryption.

The possible combinations for a DES key of 56-bit are 7.2 x 10 power16, whereas the possible combinations for the minimum AES key of 128-bit are 3.4 x 10 power38. Fastest supercomputer in the world NUDT Tianhe-2 in China would take mere seconds to break a DES whereas the AES with 128 bit could take around a billion years whereas the age of the universe it is only 13.75 billion years. Following this we can say with utmost certainty that the AES is unbreakable for the current supercomputer and it would be a very long into the future before a computer fast enough to break evena 128 bits key AES could be made.

Many attacks are launched on AES encrypted data to find its weaknesses by many cryptographers since its conception in 2000. It started mainly due to the concerns of the cryptographers that the AES is too simplistic. Many attacks were designed of which the most successful attacks till date have only been able to retrieve the key faster by a factor of 4 which is still not anywhere near to breaking the full AES. Contrary to these direct attacks, side channel attacks are also used which do not actually attack