Comsec作业五：GF(2^8)乘法证明

ComSec

'''
# File : Prove_GF.py
# Author : Hongpei Lin
# Date : 20191016
# Purpose : prove GF(2^8)
'''
import copy
mod_number=[285,299,301,333,351,355,357,361,369,391,397,425,451,463,487,501]
#multilpy in GF(2^8)
def mul(a,b,n):
    r=0
    while b:
        if b%2:
            r=r^a#add operation : XOR
        b=b>>1
        if a&int('10000000',2)==0:#hightest bit's value = 0
            a=a<<1
        else:#hightest bit's value = 1
            a=a<<1
            a=a^n
    return r
#jugde whether a list exists same element
def Judge_Same(a):
    b=copy.deepcopy(a)
    b.sort()
    for i in range(len(a)-1):
        if b[i]==b[i+1]:
            return False
    return True
#judge whether a list all values are "True"
def Judge_True(a):
    for i in a:
        if i==False:
            return False
    return True
final=[]
k=len(mod_number)-1
while k:
    result = []
    for i in range(1,256):
        subresult=[]
        for j in range(1,256):
            subresult.append(mul(i,j,mod_number[k]))
        result.append(Judge_Same(subresult))
    final.append(Judge_True(result))
    k-=1
print(Judge_True(final))