# Advanced Encryption Standard (AES Algorithm)

Advanced Encryption Standard The additional standard and wide adopted symmetrical cryptography rule possible to be encountered today is that the Advanced cryptography customary (AES). it's found a minimum of six times quicker than triple DES. Unlike DES, the amount of rounds in AES is variable and depends on the length of the key. AES uses ten rounds for 128-bit keys, twelve rounds for 192-bit keys and fourteen rounds for 256-bit keys. every of those rounds uses a distinct 128-bit round key, that is calculated from the first AES key. The schematic of AES structure is given in the following illustration Fig 1:AES Stucture Encryption Process Here, we tend to limit to description of a typical round of AES cryptography. every round comprise of 4 sub-processes. The primary round method is represented below Fig 2: The primary round method Byte Substitution (SubBytes) The sixteen input bytes are substituted by trying up a set table (S-box) given in style. The result's during a matrix of 4 rows and 4 columns. Shiftrows Each of the four rows of the matrix is shifted to the left. Any entries that ‘fall off’ ar re-inserted on the correct facet of row. Shift is allotted as follows − First row isn't shifted. Second row is shifted one (byte) position to the left. Third row is shifted 2 positions to the left. Fourth row is shifted 3 positions to the left. The result's a new matrix consisting of constant sixteen bytes however shifted with reference to one another. MixColumns Each column of 4 bytes is now transformed employing a special function. This operate takes as input the four bytes of 1 column and outputs four fully new bytes, that replace the initial column. The result's another new matrix consisting of sixteen new bytes. It ought to be noted that this step isn't performed within the last spherical. Addroundkey The sixteen bytes of the matrix ar currently thought-about as 128 bits and ar XORed to the 128 bits of the spherical key. If this is often the last round then the output is that the ciphertext. Otherwise, the ensuing 128 bits ar taken as sixteen bytes and that we begin another similar round. Fig 3: Simple Text encryption Example