DES算法 Python版本实现

主要参考朱小姐。的博客的思路
然后用Python语言实现
这也是我们电科专业的课设环节
希望对以后的学弟学妹有所帮助

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#统一按照字符串处理，输入字符串输出也是字符串。
def IP(Mingwen):
    assert len(Mingwen)==64
    IPtable=[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]
    ret=""
    for i in IPtable:
        ret=ret+Mingwen[i-1]
    return ret

#循环左移位数
def shift(a,s):

    try:
        if len(a)>28:

            raise NameError
    except TypeError:
        pass

    a=a[s:]+a[0:s]
    return a

def createSubkey(key):
    assert len(key)==64
    Clist=[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]
    Dlist=[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]
    #初试生成
    C0=""
    D0=""
    for i in Clist:
        C0+=key[i-1]
    for i in Dlist:
        D0+=key[i-1]
    assert len(C0)==28
    assert len(D0)==28

    Movetimes=[1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1]

    retkey=[]
    PC_2=[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]
    for i in range(0,16):
        C0=shift(C0,Movetimes[i])
        D0=shift(D0,Movetimes[i])
        temp=C0+D0
        tempkey=""
        for i in PC_2:
            tempkey+=temp[i-1]
        assert len(tempkey)==48
        retkey.append(tempkey)
        tempkey=""

    return retkey

def Etuozhan(Rn):
    Elist=[32,1,2,3,4,5,
4,5,6,7,8,9,
8,9,10,11,12,13,
12,13,14,15,16,17,
16,17,18,19,20,21,
20,21,22,23,24,25,
24,25,26,27,28,29,
28,29,30,31,32,1]
    retRn=""
    for i in Elist:
        retRn+=Rn[i-1]
    assert len(retRn)==48
    return retRn
S=[(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)]
Phezhihuan=[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]

def S_sub(Ln,Rn,subkey,oldRn):
    tempresult=int(Rn,base=2)^int(subkey,base=2)
    tempresult=bin(tempresult)[2:]
    while len(tempresult)<48:
        tempresult="0"+tempresult
    index=0
    retstr=""
    for list in S:
        hang=int(tempresult[index]+tempresult[index+5],base=2)
        lie=int(tempresult[index+1:index+5],base=2)
        a=bin(list[hang*16+lie])[2:]
        while len(a)<4:
            a="0"+a
        retstr+=a
        index+=6

    assert len(retstr)==32
    tmp=""
    for i in Phezhihuan:
        tmp+=retstr[i-1]

    a=int(tmp, base=2) ^ int(Ln, base=2)
    a=bin(a)[2:]
    while len(a)<32:
        a="0"+a
    assert len(a)==32
    (Ln,Rn)=(oldRn,a)
    w5555555555=Ln+Rn
    return (Ln,Rn)

def P_1(L16,R16):
    tmp=L16+R16
    list=[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]
    retstr=""
    for i in list:
       retstr+=tmp[i-1]
    assert len(retstr)==64
    return retstr

if __name__=="__main__":
    key="0001001000110100010101100111100010010001001000110100010101100111"
    Mingwen=    "1001100001110110010101000011001000010001010001110010010110000011"




    Chushizhihuan=IP(Mingwen)
    subkeylist=createSubkey(key)
    Ln=Chushizhihuan[0:32]
    Rn=Chushizhihuan[32:]
    for subkey in subkeylist:
        while len(Rn)<32:
            Rn="0"+Rn
        while len(Ln)<32:
            Ln="0"+Ln
        Rn_tuozhan=Etuozhan(Rn)
        (Ln,Rn)=S_sub(Ln,Rn_tuozhan,subkey,Rn)
        # print(hex(int(Ln+Rn,base=2))[2:].upper())
    (Ln,Rn)=(Rn,Ln)
    b=P_1(Ln,Rn)
    print(hex(int(b,base=2)).upper())