基于字母移位的一次性衬垫加密

Question

这个程序要求用户输入一个单词列表。然后，它返回一个加密单词列表和第二个列表，该列表指定用于加密这些单词的数字移位。这个想法是从https://www.khanacademy.org/computing/computer-science/cryptography/crypt/v/one-time-pad得到的。

import random

def rotate_letter(letter, number):
    if letter == ' ':
        return letter
    if letter.islower():
        start = ord('a')
    elif not letter.islower():
        start = ord('A')

    normal_shift = ord(letter) - start
    new_letter = start + (normal_shift + number) % 26
    return chr(new_letter)

def avoid(letter):
    avoid = ' ,!?¿,*+-%/@1234567890'
    for i in avoid:
        if i == letter:
            return False
    return True

def rotate_word(word):
    new_word = ''
    random_series = []
    for letter in word:
        if avoid(letter):
            random_number = random.randint(1,26)
            new_letter = rotate_letter(letter, random_number)
            new_word += new_letter
            random_series.append(random_number)
        else:
            new_word += letter
    return (new_word, random_series)

def shift(words):
    index = 0
    encrypted_words = []
    random_shifts = []
    while index < len(words):
        (new_word, random_series) = rotate_word(words[index])
        encrypted_words.append(new_word)
        random_shifts.append(random_series)
        index += 1
    return (encrypted_words, random_shifts)

def get_input():
    words = []
    while True:
        user = (input('Input words to encrypt. Done when ready \n' ))
        if user == 'Done' or user == 'done':
            return words
        words.append(user)

def start():
    words = get_input()
    encrypted_words = []
    random_shifts = []
    (encrypted_words, random_shifts) = shift(words)
    print('UNENCRYPTED WORDS', words)
    print('ENCRYPTED WORDS', encrypted_words)
    print('RANDOM SHIFTS', random_shifts)

start()

Answer 1

您的函数avoid是非常不必要的，也是令人困惑的。我希望avoid('@')返回True。当您将字母存储为全局常量和设置时，您应该获得一定的速度(因为它不需要一次又一次地重构，而且对于set来说成员资格测试非常快。我用letter not in letters_avoid代替了你的功能。

每当您在Python中进行字符串添加时，您可能做错了什么。这是因为字符串是不可变的，所以每次添加时都必须创建一个新字符串，并且需要复制要添加的字符串的内容。这太慢了。相反，可以使用list来积累new_word的字母，并在结尾处对它们进行str.join。

返回tuple时，()是隐式的。你可以直接写return a, b。

在words上迭代时，您应该直接迭代它，而不是它的索引。

使用str.lower可以将双比较if user == 'Done' or user == 'done'减少到if user.lower() == 'done':。

您应该使用if __name__ == '__main__':保护来调用您的代码，以便在不执行整个脚本的情况下从另一个脚本导入您的函数。

最终代码：

import random


letters_avoid = set(' ,!?¿,*+-%/@1234567890')


def rotate_letter(letter, number):
    if letter == ' ':
        return letter
    if letter.islower():
        start = ord('a')
    elif not letter.islower():
        start = ord('A')

    normal_shift = ord(letter) - start
    new_letter = start + (normal_shift + number) % 26
    return chr(new_letter)


def rotate_word(word):
    new_word = []
    random_series = []
    for letter in word:
        if letter not in letters_avoid:
            random_number = random.randint(1, 26)
            new_word.append(rotate_letter(letter, random_number))
            random_series.append(random_number)
        else:
            new_word.append(letter)
    return "".join(new_word), random_series


def shift(words):
    encrypted_words = []
    random_shifts = []
    for word in words:
        new_word, random_series = rotate_word(word)
        encrypted_words.append(new_word)
        random_shifts.append(random_series)
    return encrypted_words, random_shifts


def get_input():
    words = []
    while True:
        user = input('Input words to encrypt. Done when ready \n')
        if user.lower() == 'done':
            return words
        words.append(user)


def start():
    words = get_input()
    encrypted_words, random_shifts = shift(words)
    print('UNENCRYPTED WORDS', words)
    print('ENCRYPTED WORDS', encrypted_words)
    print('RANDOM SHIFTS', random_shifts)

if __name__ == "__main__":
    start()