文章目录
- 更新：
- 前言
- 实验环境
- 实验内容
- 实验操作步骤
- 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
- 5.输出处理
- 实验结果
- 实验心得
- 实验代码
- MD5-Python.py
更新：
感谢评论区的大佬指出错误，现已改进代码
之前的错误在于没有考虑最高位是0的情况
造成某些字符串的MD5加密结果与实际不符
所以对代码作出如下部分修改
原先代码
现在代码
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]:
if len(hex(register))!=10:
str1 = list(hex(register))
str1.insert(2,'0')
str2 = ''.join(str1)
register = str2[2:]
else:
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))
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