https://findneo.tech/171005NuptVigenereWP/#%E5%8F%82%E8%80%83%E9%93%BE%E6%8E%A5


题目链接和wp在链接里都有，代码也来自于链接：

# coding:utf8
# by https://findneo.github.io/
def getCipher(file='code.txt'):
    '''从文件中读取十六进制串，返回十六进制数组
    '''
    c = open(file).read()
    codeintlist = []
    codeintlist.extend(
        (map(lambda i: int(c[i:i + 2], 16), range(0, len(c), 2))))
    return codeintlist


def getKeyPool(cipher, stepSet, plainSet, keySet):
    ''' 传入的密文串、明文字符集、密钥字符集、密钥长度范围均作为数字列表处理.形如[0x11,0x22,0x33]
        返回一个字典，以可能的密钥长度为键，以对应的每一字节的密钥字符集构成的列表为值，密钥字符集为数字列表。
            形如{
                    1:[[0x11]],
                    3:[
                        [0x11,0x33,0x46],
                        [0x22,0x58],
                        [0x33]
                       ]
                }
    '''
    keyPool = dict()
    for step in stepSet:
        maybe = [None] * step
        for pos in xrange(step):
            maybe[pos] = []
            for k in keySet:
                flag = 1
                for c in cipher[pos::step]:
                    if c ^ k not in plainSet:
                        flag = 0
                if flag:
                    maybe[pos].append(k)
        for posPool in maybe:
            if len(posPool) == 0:
                maybe = []
                break
        if len(maybe) != 0:
            keyPool[step] = maybe
    return keyPool


def calCorrelation(cpool):
    '''传入字典，形如{'e':2,'p':3}
        返回可能性，0~1,值越大可能性越大
        (correlation between the decrypted column letter frequencies and
        the relative letter frequencies for normal English text)
    '''
    frequencies = {"e": 0.12702, "t": 0.09056, "a": 0.08167, "o": 0.07507, "i": 0.06966,
                   "n": 0.06749, "s": 0.06327, "h": 0.06094, "r": 0.05987, "d": 0.04253,
                   "l": 0.04025, "c": 0.02782, "u": 0.02758, "m": 0.02406, "w": 0.02360,
                   "f": 0.02228, "g": 0.02015, "y": 0.01974, "p": 0.01929, "b": 0.01492,
                   "v": 0.00978, "k": 0.00772, "j": 0.00153, "x": 0.00150, "q": 0.00095,
                   "z": 0.00074}
    relative = 0.0
    total = 0
    fpool = 'etaoinshrdlcumwfgypbvkjxqz'
    total = sum(cpool.values())  # 总和应包括字母和其他可见字符
    for i in cpool.keys():
        if i in fpool:
            relative += frequencies[i] * cpool[i] / total
    return relative


def analyseFrequency(cfreq):
    key = []
    for posFreq in cfreq:
        mostRelative = 0
        for keyChr in posFreq.keys():
            r = calCorrelation(posFreq[keyChr])
            if r > mostRelative:
                mostRelative = r
                keychar = keyChr
        key.append(keychar)

    return key


def getFrequency(cipher, keyPoolList):
    ''' 传入的密文作为数字列表处理
        传入密钥的字符集应为列表，依次包含各字节字符集。
            形如[[0x11,0x12],[0x22]]
        返回字频列表，依次为各字节字符集中每一字符作为密钥组成部分时对应的明文字频
            形如[{
                    0x11:{'a':2,'b':3},
                    0x12:{'e':6}
                 },
                 {
                    0x22:{'g':1}
                 }]
    '''
    freqList = []
    keyLen = len(keyPoolList)
    for i in xrange(keyLen):
        posFreq = dict()
        for k in keyPoolList[i]:
            posFreq[k] = dict()
            for c in cipher[i::keyLen]:
                p = chr(k ^ c)
                posFreq[k][p] = posFreq[k][p] + 1 if p in posFreq[k] else 1
        freqList.append(posFreq)
    return freqList


def vigenereDecrypt(cipher, key):
    plain = ''
    cur = 0
    ll = len(key)
    for c in cipher:
        plain += chr(c ^ key[cur])
        cur = (cur + 1) % ll
    return plain


def main():
    ps = []
    ks = []
    ss = []
    ps.extend(xrange(32, 127))
    ks.extend(xrange(0xff + 1))
    ss.extend(xrange(1, 14))
    cipher = getCipher()

    keyPool = getKeyPool(cipher=cipher, stepSet=ss, plainSet=ps, keySet=ks)
    #print len(keyPool)
    for i in keyPool:
        freq = getFrequency(cipher, keyPool[i])
        key = analyseFrequency(freq)
        plain = vigenereDecrypt(cipher, key)
        print key, plain


if __name__ == '__main__':
    main()

'''
[186, 31, 145, 178, 83, 205, 62]
Cryptography is the practice and study of techniques for,
among other things, secure communication in the presence of attackers. 
Cryptography has been used for hundreds, if not thousands, of years, 
but traditional cryptosystems were designed and evaluated in a fairly ad hoc manner. 
For example, the Vigenere encryption scheme was thought to be secure for decades after 
it was invented, but we now know, and this exercise demonstrates, that it can be broken very easily.
'''