23、维吉尼亚密码与频率分析全解析

维吉尼亚密码与频率分析全解析

1. 维吉尼亚密码程序概述

维吉尼亚密码是一种多字母替换密码，与凯撒密码类似，但使用多个密钥而非单个密钥。以下是维吉尼亚密码程序的基本结构和功能：

# Vigenere Cipher (Polyalphabetic Substitution Cipher)
# https://www.nostarch.com/crackingcodes/ (BSD Licensed)

import pyperclip

LETTERS = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'

def main():
    # This text can be downloaded from https://www.nostarch.com/crackingcodes/:
    myMessage = """Alan Mathison Turing was a British mathematician,
          logician, cryptanalyst, and computer scientist."""
    myKey = 'ASIMOV'
    myMode = 'encrypt'  # Set to either 'encrypt' or 'decrypt'.

    if myMode == 'encrypt':
        translated = encryptMessage(myKey, myMessage)
    elif myMode == 'decrypt':
        translated = decryptMessage(myKey, myMessag