Note:code is under development

SHA-3-Python

Python 3 code for SHA-3 cryptographic algorithm This code has clean and easy to understand the implementation of SHA-3 Cryptographic Algorithm.Comments are done to make it easier to understand for someone who is new to SHA-3 and python.SHA-3 falls under sponge functions while sha-0,sha-1,sha-2 and MD-5 hash functions fall under Merkle Damgard construction.

Note:It's still under progress

There are four levels of security in SHA-3 as follows

Type	Output Length	Rate (r)	Capacity (c)
SHA3-224	224	1152	448
SHA3-256	256	1088	512
SHA3-384	384	832	768
SHA3-512	512	576	1024

Stage 1: Stage 1 is Padding stage

Stage 2: Stage 2 is State size

Stage 3: Stage 3 is Aborbing phase

Stage 4: Stage 4 is Squeezing phase

Padding:

The input M to the hash algorithm SHA-3 is padded with 10∗1, i.e. two 1’s and as many 0’s in between (possibly none) until the padded length is a multiple of 1088 (= 1600−512)(Rate r Changes with SHA-3 type i.e SHA-256). You must append at least two 1’s, with as many 0’s in between (possibly none) so that the padded length is a multiple of 1088.

The F-Function Of SHA-3

The f-Function of SHA-3 Consists of 5 sub-Functions which are theta,rho,pi,chi and iota. In order to understand these 5 sub_functions,we divide the input 1600 bits state into 5x5 matrix and each one of the matrix has 64 bits(64 bit register=1 word) making it 5x5x64.

Theta:

    Each of 1600 state bits are replaced by the XOR sum of 11 bits:
    (The original bit) XOR (5 bit column "to the left" of the bit) XOR  (5 bit column "to the right"  and one position "to the front" of the bit).

rho:

 Each word is rotated by a fixed number of position by a fixed table.

pi:

 We Permutate the 64 bit words locations in 5x5 matrix.

chi:

  A_out [i][j][k] = A[i][j][k] XOR ( (A[i + 1][j][k] XOR 1) AND (ain[i + 2][j][k]) )

iota:

  Add constants  to word (0,0)