前言
实验目的
1）初步了解哈希算法
2）掌握哈希算法MD5的实现
提示：以下是本篇文章正文内容，下面案例可供参考
实验环境
计算机语言：Python
开发环境：Pycharm
实验内容
编程实现MD5算法。
实验操作步骤
编写MD5类
初始化配置各参数
1.初始化四个缓冲区
2.设置常数表、位移位数等参数
3.增加填充
4.分组处理
分为四个分组，FF,GG,HH,II
每组对消息message的不同单位进行加密
分组处理，每次循环移动四位
5.输出处理
实验结果
1.明文：12345678
密文：25d55ad23a80aa4f464c76d713c07ad
与在线加密结果一致
2.明文：hello world
密文：5eb63bbbe01eeed093cb22bb8f5acdc3
与在线加密结果一致
实验心得
本次实验是MD5算法的编写，通过本次python代码编写实现了加密功能，编写的思路从MD5算法原理出发，通过初始化缓冲区、附加填充位、分组进行加密等步骤，构造类来实现功能，相较于RSA，MD5是不可逆算法，应该会更加安全一些，但我查阅资料后发现并非如此，在线的MD5库可以解密数量巨大的MD5密文，只有在“加盐”过后才会使得破解难度大大增加。
实验代码
MD5-Python.py
# -*- codeding = uft-8 -*-
def int2bin(n, count=24):
return "".join([str((n >> y) & 1) for y in range(count-1, -1, -1)])
class MD5(object):
# 初始化密文
def __init__(self, message):
self.message = message
self.ciphertext = ""
self.A = 0x67452301
self.B = 0xEFCDAB89
self.C = 0x98BADCFE
self.D = 0x10325476
self.init_A = 0x67452301
self.init_B = 0xEFCDAB89
self.init_C = 0x98BADCFE
self.init_D = 0x10325476
'''
self.A = 0x01234567
self.B = 0x89ABCDEF
self.C = 0xFEDCBA98
self.D = 0x76543210
'''
#设置常数表T
self.T = [0xD76AA478,0xE8C7B756,0x242070DB,0xC1BDCEEE,0xF57C0FAF,0x4787C62A,0xA8304613,0xFD469501,
0x698098D8,0x8B44F7AF,0xFFFF5BB1,0x895CD7BE,0x6B901122,0xFD987193,0xA679438E,0x49B40821,
0xF61E2562,0xC040B340,0x265E5A51,0xE9B6C7AA,0xD62F105D,0x02441453,0xD8A1E681,0xE7D3FBC8,
0x21E1CDE6,0xC33707D6,0xF4D50D87,0x455A14ED,0xA9E3E905,0xFCEFA3F8,0x676F02D9,0x8D2A4C8A,
0xFFFA3942,0x8771F681,0x6D9D6122,0xFDE5380C,0xA4BEEA44,0x4BDECFA9,0xF6BB4B60,0xBEBFBC70,
0x289B7EC6,0xEAA127FA,0xD4EF3085,0x04881D05,0xD9D4D039,0xE6DB99E5,0x1FA27CF8,0xC4AC5665,
0xF4292244,0x432AFF97,0xAB9423A7,0xFC93A039,0x655B59C3,0x8F0CCC92,0xFFEFF47D,0x85845DD1,
0x6FA87E4F,0xFE2CE6E0,0xA3014314,0x4E0811A1,0xF7537E82,0xBD3AF235,0x2AD7D2BB,0xEB86D391]
#循环左移位数
self.s = [7,12,17,22,7,12,17,22,7,12,17,22,7,12,17,22,
5,9,14,20,5,9,14,20,5,9,14,20,5,9,14,20,
4,11,16,23,4,11,16,23,4,11,16,23,4,11,16,23,
6,10,15,21,6,10,15,21,6,10,15,21,6,10,15,21]
self.m = [0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,
1,6,11,0,5,10,15,4,9,14,3,8,13,2,7,12,
5,8,11,14,1,4,7,10,13,0,3,6,9,12,15,2,
0,7,14,5,12,3,10,1,8,15,6,13,4,11,2,9]
# 附加填充位
def fill_text(self):
for i in range(len(self.message)):
c = int2bin(ord(self.message[i]), 8)
self.ciphertext += c
if (len(self.ciphertext)%512 != 448):
if ((len(self.ciphertext)+1)%512 != 448):
self.ciphertext += '1'
while (len(self.ciphertext)%512 != 448):
self.ciphertext += '0'
length = len(self.message)*8
if (length <= 255):
length = int2bin(length, 8)
else:
length = int2bin(length, 16)
temp = length[8:12]+length[12:16]+length[0:4]+length[4:8]
length = temp
self.ciphertext += length
while (len(self.ciphertext)%512 != 0):
self.ciphertext += '0'
# 分组处理（迭代压缩）
def circuit_shift(self, x, amount):
x &= 0xFFFFFFFF
return ((x << amount) | (x >> (32 - amount))) & 0xFFFFFFFF
def change_pos(self):
a = self.A
b = self.B
c = self.C
d = self.D
self.A = d
self.B = a
self.C = b
self.D = c
def FF(self, mj, s, ti):
mj = int(mj, 2)
temp = self.F(self.B, self.C, self.D) + self.A + mj + ti
temp = self.circuit_shift(temp, s)
self.A = (self.B + temp)%pow(2, 32)
self.change_pos()
def GG(self, mj, s, ti):
mj = int(mj, 2)
temp = self.G(self.B, self.C, self.D) + self.A + mj + ti
temp = self.circuit_shift(temp, s)
self.A = (self.B + temp)%pow(2, 32)
self.change_pos()
def HH(self, mj, s, ti):
mj = int(mj, 2)
temp = self.H(self.B, self.C, self.D) + self.A + mj + ti
temp = self.circuit_shift(temp, s)
self.A = (self.B + temp)%pow(2, 32)
self.change_pos()
def II(self, mj, s, ti):
mj = int(mj, 2)
temp = self.I(self.B, self.C, self.D) + self.A + mj + ti
temp = self.circuit_shift(temp, s)
self.A = (self.B + temp)%pow(2, 32)
self.change_pos()
def F(self, X, Y, Z):
return (X & Y) | ((~X) & Z)
def G(self, X, Y, Z):
return (X & Z) | (Y & (~Z))
def H(self, X, Y, Z):
return X ^ Y ^ Z
def I(self, X, Y, Z):
return Y ^ (X | (~Z))
def group_processing(self):
M = []
for i in range(0, 512, 32):
num = ""
# 获取每一段的标准十六进制形式
for j in range(0, len(self.ciphertext[i:i+32]), 4):
temp = self.ciphertext[i:i+32][j:j + 4]
temp = hex(int(temp, 2))
num += temp[2]
# 对十六进制进行小端排序
num_tmp = ""
for j in range(8, 0, -2):
temp = num[j-2:j]
num_tmp += temp
num = ""
for i in range(len(num_tmp)):
num += int2bin(int(num_tmp[i], 16), 4)
M.append(num)
#print(M)
for j in range(0, 16, 4):
self.FF(M[self.m[j]], self.s[j], self.T[j])
self.FF(M[self.m[j+1]], self.s[j+1], self.T[j+1])
self.FF(M[self.m[j+2]], self.s[j+2], self.T[j+2])
self.FF(M[self.m[j+3]], self.s[j+3], self.T[j+3])
for j in range(0, 16, 4):
self.GG(M[self.m[16+j]], self.s[16+j], self.T[16+j])
self.GG(M[self.m[16+j+1]], self.s[16+j+1], self.T[16+j+1])
self.GG(M[self.m[16+j+2]], self.s[16+j+2], self.T[16+j+2])
self.GG(M[self.m[16+j+3]], self.s[16+j+3], self.T[16+j+3])
for j in range(0, 16, 4):
self.HH(M[self.m[32+j]], self.s[32+j], self.T[32+j])
self.HH(M[self.m[32+j+1]], self.s[32+j+1], self.T[32+j+1])
self.HH(M[self.m[32+j+2]], self.s[32+j+2], self.T[32+j+2])
self.HH(M[self.m[32+j+3]], self.s[32+j+3], self.T[32+j+3])
for j in range(0, 16, 4):
self.II(M[self.m[48+j]], self.s[48+j], self.T[48+j])
self.II(M[self.m[48+j+1]], self.s[48+j+1], self.T[48+j+1])
self.II(M[self.m[48+j+2]], self.s[48+j+2], self.T[48+j+2])
self.II(M[self.m[48+j+3]], self.s[48+j+3], self.T[48+j+3])
self.A = (self.A+self.init_A)%pow(2, 32)
self.B = (self.B+self.init_B)%pow(2, 32)
self.C = (self.C+self.init_C)%pow(2, 32)
self.D = (self.D+self.init_D)%pow(2, 32)
'''
print("A:{}".format(hex(self.A)))
print("B:{}".format(hex(self.B)))
print("C:{}".format(hex(self.C)))
print("D:{}".format(hex(self.D)))
'''
answer = ""
for register in [self.A, self.B, self.C, self.D]:
register = hex(register)[2:]
for i in range(8, 0, -2):
answer += str(register[i-2:i])
return answer
message = input("输入要加密的字符串：")
MD5 = MD5(message)
MD5.fill_text()
result = MD5.group_processing()
print("32位小写MD5加密：{}".format(result))
