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SM4国密算法原理及python代码实现

SM4简介

SM4.0(原名SMS4.0)是中华人民共和国政府采用的一种分组密码标准,由国家密码管理局于2012年3月21日发布。相关标准为“GM/T 0002-2012《SM4分组密码算法》(原SMS4分组密码算法)”。
在商用密码体系中,SM4主要用于数据加密,其算法公开,分组长度与密钥长度均为128bit,加密算法与密钥扩展算法都采用32轮非线性迭代结构,S盒为固定的8比特输入8比特输出。
SM4.0中的指令长度被提升到大于64K(即64×1024)的水平,这是SM 3.0规格(渲染指令长度允许大于512)的128倍。

算法原理

基本构建

输入明文(x0,x1,x2 , x3) 128位,共四个32位字。
输入轮密钥:rki(i=0,1…,31) 共32个32位字轮密钥
输出密文(y0,y1,y2,y3) 128位,四个32位字
算法结构:轮函数32轮迭代,每轮使用一个密钥:
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具体运算

S盒

8输入8输出的密码构建,由前四个比特决定行号,后四个比特决定列号,行号列号确定输出。是唯一的非线性构建。
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非线性字变换

相当于四个s盒并置。输入32位字A=(a0,a1,a2,a3),输出B=(b0,b1,b2,b3)。
B=(s-box(a0),s-box(a1),s-box(a2),s-box(a3))
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线性L变换

32位输入,32位输出,属于简单的线性变换。
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字变换组合与轮函数

字变换组合输入32位,输出32位,即先进行非线性字变换再进行线性L变换。
在这里插入图片描述
轮函数:
输入128位字X=(x0,x1,x2,x3),每个xi为32位字。
输入轮密钥:rk,32位字
输出32位字的数据
轮函数运算过程如下:
在这里插入图片描述

密钥生成

常量参数

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SM4密钥扩展算法

输入加密密钥128位MK=(MK0.MK1.MK2.MK3)
输出轮密钥每个32位:rki( i=0,1,2…,31)
中间数据每个32位Ki( i=0,1,2…,35)
算法流程如下::

解密算法

SM4加解密算法是对合的,因此只需要反向使用轮密钥即可解密。
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编程实现

这个算法都是基本运算,编程实现难度不大,由于是对合运算所以我只编写了加密部分,话不多说上代码:

sbox =[[0xd6,0x90,0xe9,0xfe,0xcc,0xe1,0x3d,0xb7,0x16,0xb6,0x14,0xc2,0x28,0xfb,0x2c,0x05,],[0x2b,0x67,0x9a,0x76,0x2a,0xbe,0x04,0xc3,0xaa,0x44,0x13,0x26,0x49,0x86,0x06,0x99,],[0x9c,0x42,0x50,0xf4,0x91,0xef,0x98,0x7a,0x33,0x54,0x0b,0x43,0xed,0xcf,0xac,0x62,],[0xe4,0xb3,0x1c,0xa9,0xc9,0x08,0xe8,0x95,0x80,0xdf,0x94,0xfa,0x75,0x8f,0x3f,0xa6,],[0x47,0x07,0xa7,0xfc,0xf3,0x73,0x17,0xba,0x83,0x59,0x3c,0x19,0xe6,0x85,0x4f,0xa8,],[0x68,0x6b,0x81,0xb2,0x71,0x64,0xda,0x8b,0xf8,0xeb,0x0f,0x4b,0x70,0x56,0x9d,0x35,],[0x1e,0x24,0x0e,0x5e,0x63,0x58,0xd1,0xa2,0x25,0x22,0x7c,0x3b,0x01,0x21,0x78,0x87,],[0xd4,0x00,0x46,0x57,0x9f,0xd3,0x27,0x52,0x4c,0x36,0x02,0xe7,0xa0,0xc4,0xc8,0x9e,],[0xea,0xbf,0x8a,0xd2,0x40,0xc7,0x38,0xb5,0xa3,0xf7,0xf2,0xce,0xf9,0x61,0x15,0xa1,],[0xe0,0xae,0x5d,0xa4,0x9b,0x34,0x1a,0x55,0xad,0x93,0x32,0x30,0xf5,0x8c,0xb1,0xe3,],[0x1d,0xf6,0xe2,0x2e,0x82,0x66,0xca,0x60,0xc0,0x29,0x23,0xab,0x0d,0x53,0x4e,0x6f,],[0xd5,0xdb,0x37,0x45,0xde,0xfd,0x8e,0x2f,0x03,0xff,0x6a,0x72,0x6d,0x6c,0x5b,0x51,],[0x8d,0x1b,0xaf,0x92,0xbb,0xdd,0xbc,0x7f,0x11,0xd9,0x5c,0x41,0x1f,0x10,0x5a,0xd8,],[0x0a,0xc1,0x31,0x88,0xa5,0xcd,0x7b,0xbd,0x2d,0x74,0xd0,0x12,0xb8,0xe5,0xb4,0xb0,],[0x89,0x69,0x97,0x4a,0x0c,0x96,0x77,0x7e,0x65,0xb9,0xf1,0x09,0xc5,0x6e,0xc6,0x84,],[0x18,0xf0,0x7d,0xec,0x3a,0xdc,0x4d,0x20,0x79,0xee,0x5f,0x3e,0xd7,0xcb,0x39,0x48]]

FK0=0XA3B1BAC6
FK1=0X56AA3350
FK2=0X677D9197
FK3=0XB27022DC

CK =[0x00070e15,0x1c232a31,0x383f464d,0x545b6269,0x70777e85,0x8c939aa1,0xa8afb6bd,0xc4cbd2d9,0xe0e7eef5,0xfc030a11,0x181f262d,0x343b4249,0x50575e65,0x6c737a81,0x888f969d,0xa4abb2b9,0xc0c7ced5,0xdce3eaf1,0xf8ff060d,0x141b2229,0x30373e45,0x4c535a61,0x686f767d,0x848b9299,0xa0a7aeb5,0xbcc3cad1,0xd8dfe6ed,0xf4fb0209,0x10171e25,0x2c333a41,0x484f565d,0x646b7279]

rk =[0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0]#初始轮密钥全部置零defxun(X,i):#循环左移return((X<<i)&0xffffffff)|(X>>(32-i))defs_(x):#s盒 8输入8输出
    row = x >>4
    nuw = x &0xfreturn sbox[row][nuw]defL_(x):#线性L变换 32输入32输出return x^xun(x,2)^xun(x,10)^xun(x,18)^xun(x,24)defT_(x):#字变换组合 32输入32输出
    a0 =(x >>24)&0xff
    a1 =(x >>16)&0xff
    a2 =(x >>8)&0xff
    a3 =(x >>0)&0xff
    B =(s_(a0)<<24)^(s_(a1)<<16)^(s_(a2)<<8)^(s_(a3)<<0)#先s盒变换return L_(B)#再L变换defT(x):#密钥扩展字变换
    a0 =(x >>24)&0xff
    a1 =(x >>16)&0xff
    a2 =(x >>8)&0xff
    a3 =(x >>0)&0xff
    B =(s_(a0)<<24)^(s_(a1)<<16)^(s_(a2)<<8)^(s_(a3)<<0)# 先s盒变换return B ^(xun(B,13))^(xun(B,23))defK_(MK0,MK1,MK2,MK3):#SM4密钥扩展算法
    K =[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
    K[0]= MK0 ^ FK0
    K[1]= MK1 ^ FK1
    K[2]= MK2 ^ FK2
    K[3]= MK3 ^ FK3
    for i inrange(32):
        rk[i]=K[i+4]=K[i]^T(K[i+1]^K[i+2]^K[i+3]^CK[i])defSMJ(x):#SM4加密算法
    X =[0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0,0x0]
    X[0]=(x >>96)&0xffffffff
    X[1]=(x >>64)&0xffffffff
    X[2]=(x >>32)&0xffffffff
    X[3]=(x >>0)&0xfffffffffor i inrange(33):
        X[i+4]= X[i]^T_(X[i+1]^X[i+2]^X[i+3]^rk[i])#轮函数return(X[35]<<96)^(X[34]<<64)^(X[33]<<32)^X[32]if __name__ =='__main__':
    MK =int(input("请输入加密密钥: "),16)
    MK0=(MK>>96)&0Xffffffff
    MK1=(MK>>64)&0Xffffffff
    MK2=(MK>>32)&0Xffffffff
    MK3=(MK>>0)&0Xffffffff
    K_(MK0, MK1, MK2, MK3)
    x =int(input("请输入明文: "),16)print("密文为:{:x}".format(SMJ(x)))

本文转载自: https://blog.csdn.net/noj_h/article/details/127632630
版权归原作者 zzj753 所有, 如有侵权,请联系我们删除。

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