[代码仓库]DES加密算法

本篇代码是在完成老师应用密码学实验时完成的，有一些想法还可以，可以留给自己以及后辈参考，关于DES加密的原理不多讲述。

编程语言：python3

def jiami(m,k):#m 为明文  k为密钥   均为二进制转换来的字符串.摘掉了0b
    ki=getSubKey(k)#得到子密钥序列                  
    #轮密钥加密
    m_after_ip=IP(m)             
    l0=m_after_ip[:32]#完成左右交换
    r0=m_after_ip[32:]

    for i in range(16):
        l1=r0
        r1=str(bin(int(l0,2)^int(f(r0,ki[i]),2)))[2:]#经典的二进制/十六进制数字型与字符型转换
        r1=fill(r1,32)
        l0=l1
        r0=r1

    t=r0+l0

    c=NIP(t)#进行IP逆置换（但是似乎有点多余）
    return c

def getSubKey(k):#得到子密钥分组,一个字符串组成的列表

    k56=PC1(k)                         

    c=k56[:28]
    d=k56[28:]
    sk=[]#列表
    ls=[1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1,]
    for i in range(16):
        c1=LS(c,ls[i])
        d1=LS(d,ls[i])
        sk.append(PC2(c1+d1))
        
        c=c1
        d=d1
    return sk

def IP(m):#得到第一次IP置换结果
    ip=[58,50,42,34,26,18,10,2,60,52,44,36,28,20,12,4,
        62,54,46,38,30,22,14,6,64,56,48,40,32,24,16,8,
        57,49,41,33,25,17,9,1,59,51,43,35,27,19,11,3,
        61,53,45,37,29,21,13,5,63,55,47,39,31,23,15,7,]
    MAI=''
    for i in range(64):
        MAI+=m[ip[i]-1]
    return MAI

def JIP(m):#解密得到第一次IP置换结果
    ip=[58,50,42,34,26,18,10,2,60,52,44,36,28,20,12,4,
        62,54,46,38,30,22,14,6,64,56,48,40,32,24,16,8,
        57,49,41,33,25,17,9,1,59,51,43,35,27,19,11,3,
        61,53,45,37,29,21,13,5,63,55,47,39,31,23,15,7,]
    MAI=''
    for i in range(64):
        MAI+=m[ip.index(i+1)]
    return MAI

def NIP(t):#逆IP置换 
    nip=[40,8,48,16,56,24,64,32,39,7,47,15,55,23,63,31,
         38,6,46,14,54,22,62,30,37,5,45,13,53,21,61,29,
         36,4,44,12,52,20,60,28,35,3,43,11,51,19,59,27,
         34,2,42,10,50,18,58,26,33,1,41,9,49,17,57,25,]
    NAI=''
    for i in range(64):
        NAI+=t[nip[i]-1]
    return NAI

def JNIP(t):#解密逆IP置换
    nip=[40,8,48,16,56,24,64,32,39,7,47,15,55,23,63,31,
         38,6,46,14,54,22,62,30,37,5,45,13,53,21,61,29,
         36,4,44,12,52,20,60,28,35,3,43,11,51,19,59,27,
         34,2,42,10,50,18,58,26,33,1,41,9,49,17,57,25,]
    NAI=''
    for i in range(64):
        NAI+=t[nip.index(i+1)]
    return NAI

def PC1(k):#返回字符串
    pc1=[57,49,41,33,25,17,9,
         1,58,50,42,34,26,18,
         10,2,59,51,43,35,27,
         19,11,3,60,52,44,36,
         63,55,47,39,31,23,15,
         7,62,54,46,38,30,22,
         14,6,61,53,45,37,29,
         21,13,5,28,20,12,4,]
    k56=''
    for i in range(56):
        k56+=k[pc1[i]-1]
    return k56

def PC2(k):#返回字符串
    pc2=[14,17,11,24,1,5,3,28,
         15,6,21,10,23,19,12,4,
         26,8,16,7,27,20,13,2,
         41,52,31,37,47,55,30,40,
         51,45,33,48,44,49,39,56,
         34,53,46,42,50,36,29,32]
    k48=''
    for i in range(48):
        k48+=k[pc2[i]-1]
    return k48

def LS(c,n):#返回字符串，用来进行移位操作
    head=c[:n]
    tail=c[n:]
    return tail+head

def P(s):#P置换
    p=[16,7,20,21,29,12,28,17,1,15,23,26,5,18,31,10,2,8,24,14,32,27,3,9,19,13,30,6,22,11,4,25,]
    p32=''
    for i in range(32):
        p32+=s[p[i]-1]
    return p32


def S(s0):#S替换
    
    sbox=[
    [14,4,13,1,2,15,11,8,3,10,6,12,5,9,0,7,
        0,15,7,4,14,2,13,1,10,6,12,11,9,5,3,8,
        4,1,14,8,13,6,2,11,15,12,9,7,3,10,5,0,
        15,12,8,2,4,9,1,7,5,11,3,14,10,0,6,13,],
    [15,1,8,14,6,11,3,4,9,7,2,13,12,0,5,10,
        3,13,4,7,15,2,8,14,12,0,1,10,6,9,11,5,
        0,14,7,11,10,4,13,1,5,8,12,6,9,3,2,15,
        13,8,10,1,3,15,4,2,11,6,7,12,0,5,14,9,],
    [10,0,9,14,6,3,15,5,1,13,12,7,11,4,2,8,
        13,7,0,9,3,4,6,10,2,8,5,14,12,11,15,1,
        13,6,4,9,8,15,3,0,11,1,2,12,5,10,14,7,
        1,10,13,0,6,9,8,7,4,15,14,3,11,5,2,12,],
    [7,13,14,3,0,6,9,10,1,2,8,5,11,12,4,15,
        13,8,11,5,6,15,0,3,4,7,2,12,1,10,14,9,
        10,6,9,0,12,11,7,13,15,1,3,14,5,2,8,4,
        3,15,0,6,10,1,13,8,9,4,5,11,12,7,2,14,],
    [2,12,4,1,7,10,11,6,8,5,3,15,13,0,14,9,
        14,11,2,12,4,7,13,1,5,0,15,10,3,9,8,6,
        4,2,1,11,10,13,7,8,15,9,12,5,6,3,0,14,
        11,8,12,7,1,14,2,13,6,15,0,9,10,4,5,3,],
    [12,1,10,15,9,2,6,8,0,13,3,4,14,7,5,11,
        10,15,4,2,7,12,9,5,6,1,13,14,0,11,3,8,
        9,14,15,5,2,8,12,3,7,0,4,10,1,13,11,6,
        4,3,2,12,9,5,15,10,11,14,1,7,6,0,8,13,],
    [4,11,2,14,15,0,8,13,3,12,9,7,5,10,6,1,
        13,0,11,7,4,9,1,10,14,3,5,12,2,15,8,6,
        1,4,11,13,12,3,7,14,10,15,6,8,0,5,9,2,
        6,11,13,8,1,4,10,7,9,5,0,15,14,2,3,12,],
    [13,2,8,4,6,15,11,1,10,9,3,14,5,0,12,7,
        1,15,13,8,10,3,7,4,12,5,6,11,0,14,9,2,
        7,11,4,1,9,12,14,2,0,6,10,13,15,3,5,8,
        2,1,14,7,4,10,8,13,15,12,9,0,3,5,6,11,],]
    s=''
    for i in range(8):  
        s+=fill((str(bin(sbox[i]
                    [int
                     ((s0[i*6]+s0[i*6+5]),2)*16+int((s0[i*6+1]+s0[i*6+2]+s0[i*6+3]+s0[i*6+4]),2)
                    ]))[2:]),4)
    return s

def fill(s,n):#填充0，防止转换时位数缺失
    if len(s)==n:
        return s
    count=n-len(s)
    zero='0'
    for i in range(count):
        s=zero+s
    return s

def f(r0,k):
    r=E(r0)
    s0=str(bin(int(r,2)^int(k,2)))[2:]  
    s0=fill(s0,48)           
    s=S(s0)
    c=P(s)
    return c

def E(r0):
    r=''
    for i in range(8):
        r+=r0[((i*4+31)%32)]
        r+=r0[i*4]
        r+=r0[i*4+1]
        r+=r0[i*4+2]
        r+=r0[i*4+3]
        r+=r0[(i+1)*4%32]
    return r
#####################################中文转换为十六进制
def ChtoHex(t):
    data=bytearray(t.encode())
    s=''
    for char in data:
        s+=hex(char)[2:].rjust(2,'0')
    return s
################################################十六进制换回中文
def HextoCh(s):
    
    a=bytearray.fromhex(s)
    b=b''
    
    for char in a:
        b+=bytes.fromhex(fill(str(hex(char))[2:],2))
    c=b.decode()
    return c
###############################################33
def jiemi(c,k):
    ki=getSubKey(k)
    ki.reverse()
    c_after_NIP=JNIP(c)
    l0=c_after_NIP[32:]
    r0=c_after_NIP[:32]
    for i in range(16):
        r1=l0
        l1=str(bin(int(r0,2)^int(f(l0,ki[i]),2)))[2:]
        l1=fill(l1,32)
        r0=r1
        l0=l1
    t=l0+r0
    m=JIP(t)
    return m

    
def ECBjiami():
    fm=open('des_messages.txt','r',encoding='ansi')
    fk=open('des_key.txt','r')
    m=str(bin(int(ChtoHex(fm.read()),16)))[2:]
    if len(m)%4!=0:
        m=fill(m,(len(m)//4+1)*4)
    k=str(bin(int(fk.read(),16)))[2:]
    k=fill(k,64)
    long=len(m)
    if (long%64!=0):
        count=64-long%64
        for i in range(count):
            m+='0'
    n=len(m)//64   
    c=''   
    print("明文为：",hex(int(m,2)))
    print("密钥为：",hex(int(k,2)))    
    for i in range(n):
        c+=jiami(m[i*64:(i+1)*64],k)
    fm.close()
    fk.close()
    return hex(int(c,2))[2:]

def ECBjiemi():
    fc=open('des_secret.txt','r')
    fk=open('des_key.txt','r')
    c=str(bin(int(fc.read(),16)))[2:]
    if len(c)%64!=0:
        c=fill(c,(len(c)//64+1)*64)
    k=str(bin(int(fk.read(),16)))[2:]
    k=fill(k,64)
    n=len(c)//64
    m=''
    print("密文为：",hex(int(c,2)))
    print("密钥为：",hex(int(k,2)))
    
    for i in range(n):
        m+=jiemi(c[i*64:(i+1)*64],k)
    
    fc.close()
    fk.close()
    return HextoCh(hex(int(m,2))[2:])
    
def CBCjiami():
    fm=open('des_messages.txt','r',encoding='ansi')
    fk=open('des_key.txt','r')
    fiv=open('des_iv.txt','r')
    m=str(bin(int(ChtoHex(fm.read()),16)))[2:]
    if len(m)%4!=0:
        m=fill(m,(len(m)//4+1)*4)
    k=str(bin(int(fk.read(),16)))[2:]
    k=fill(k,64)
    iv=str(bin(int(fiv.read(),16)))[2:]
    iv=fill(iv,64)
    long=len(m)
    if (long%64!=0):
        count=64-long%64
        for i in range(count):
            m+='0'
    n=len(m)//64  
    c=''
    print("明文为：",hex(int(m,2)))
    print("密钥为：",hex(int(k,2)))
    print("向量为：",hex(int(iv,2)))
    for i in range(n):
        m0=m[i*64:(i+1)*64]
        mi=str(bin(int(m0,2)^int(iv,2)))[2:]
        mi=fill(mi,64)
        iv=jiami(mi,k)
        c+=iv       
    fm.close()
    fk.close()
    fiv.close()
    return hex(int(c,2))[2:]


def CBCjiemi():
    fc=open('des_secret.txt','r')
    fk=open('des_key.txt','r')
    fiv=open('des_iv.txt','r')
    c=str(bin(int(fc.read(),16)))[2:]
    if len(c)%64!=0:
        c=fill(c,(len(c)//64+1)*64)
    k=str(bin(int(fk.read(),16)))[2:]
    k=fill(k,64)
    iv=str(bin(int(fiv.read(),16)))[2:]
    iv=fill(iv,64)
    n=len(c)//64  
    m='' 
    print("密文为：",hex(int(c,2)))
    print("密钥为：",hex(int(k,2)))
    print("向量为：",hex(int(iv,2)))   
    for i in range(n):
        c0=c[i*64:(i+1)*64]
        m0=str(bin(int(jiemi(c0,k),2)^int(iv,2)))[2:]
        m0=fill(m0,64)
        m+=m0
        iv=c0   
    fc.close()
    fk.close()
    fiv.close()
    return HextoCh(hex(int(m,2))[2:])
    
def main():
    print("This is based on py3
 input 1 to use ECB and input 2 to use CBC and input 0 to exit
")
    while(1):
        i=input()
        if i=='0' :
            break
        elif (i=='1'):
            print("ECB:input 1 for jiami or 2 for jiemi
")
            j=input()
            if(j=='1'):
                print("加密结果为"+str(ECBjiami()))
            else:
                print("解密结果为"+str(ECBjiemi()))
        else:
            print("CBC:input 1 for jiami or 2 for jiemi
")
            j=input()
            if(j=='1'):
                print("加密结果为"+str(CBCjiami()))
            else:
                print("解密结果为"+str(CBCjiemi()))

main()