隐写术之Base64隐写

def splitStringByLength(string, length):    handleList = []    tempString = ""    count = 0    for char in string:        tempString += char        count += 1        if count == length:            handleList.append(tempString)            count = 0            tempString = ""    return handleListdef base64AlphabetGenerator():    bs64Alphabet = {}    originUpperChar = 'A'    originLowerChar = 'a'    originNumberChar = '0'    for i in range(0, 62):        if i < 26:            bs64Alphabet[i] = chr(ord(originUpperChar) + i)        elif i < 52:            bs64Alphabet[i] = chr(ord(originLowerChar) + i - 26)        elif i < 62:            bs64Alphabet[i] = chr(ord(originNumberChar) + i - 52)    bs64Alphabet[62] = '+'    bs64Alphabet[63] = '/'    return bs64Alphabetdef findKeyByValue(keyValue, bs64Alphabet):    for key, value in bs64Alphabet.items():        if value == keyValue:            return key    return -1fileName = "ComeOn!.txt"with open(fileName, 'r') as f:    contents = f.readlines()f.close()stegBinaryInfoList = []base64Alphabet = base64AlphabetGenerator()for content in contents:    equalCount = content.count('=')    # 不处理没有带填充字符（=）的字符串    if equalCount == 0:        continue    binaryString = ""    content = content.replace('=', '').replace('n', '')    for char in content:        key = findKeyByValue(char, base64Alphabet)        tempString = format(key & 0xFF, '08b')        tempString = tempString[2:]        binaryString += tempString    stegBinaryInfo = binaryString[-(equalCount * 2):]    if stegBinaryInfo != "":        stegBinaryInfoList.append(stegBinaryInfo)stegBinaryInfoString = ""for element in stegBinaryInfoList:    stegBinaryInfoString += elementhandleBinaryList = splitStringByLength(stegBinaryInfoString, 8)flag = ""for binaryString in handleBinaryList:    flag += chr(int(binaryString, 2))print(flag)