AAF(Affine)

题目

解

或

import gmpy2
flag = "WMPTPTRGGPED"  
flags = ''
for i in flag:  
    i = ord(i)-ord("A")
    j = (gmpy2.invert(3,26)*(i-17))%26
    flags += chr(j+ord("A"))  
print(flags)

关于Affine的加解密脚本如下：

import gmpy2
flag = "WMPTPTRGGPED"  
def decode(x):
    target = ""
    for i in x:  
        i = ord(i)-ord("A")
        j = (gmpy2.invert(3,26)*(i-17))%26
        target += chr(j+ord("A"))  
    return target
def encode(x):
    target = ''
    for i in x:
        i = ord(i)-65
        j = (3 * i + 17)%26
        target +=chr(j+65)
    return target
flag = decode(flag)
print("decode>>>",flag)
flag = encode(flag)
print("encode>>>",flag)