Python编程实现凯撒密码加密示例
作者:༄༊ξ李的脏脏星࿐ 发布时间:2021-04-22 01:58:56
标签:Python,凯撒密码,加密
一、什么是凯撒密码
“在密码学中,恺撒密码(英语:Caesar cipher),或称恺撒加密、恺撒变换、变换加密,是一种最简单且最广为人知的加密技术。它是一种替换加密的技术,明文中的所有字母都在字母表上向后(或向前)按照一个固定数目进行偏移后被替换成密文。例如,当偏移量是3的时候,所有的字母A将被替换成D,B变成E,以此类推。这个加密方法是以罗马共和时期恺撒的名字命名的,当年恺撒曾用此方法与其将军们进行联系。”
关于凯撒密码的详细介绍:恺撒密码_百度百科
二、python实现凯撒加密
凯撒密码程序的源代码 :
在文件编辑器中建立.py文件,并将其保存为caesarCipher.py。然后将本文配套资源
中的pyperclip.py模块放在与 caesarCipher.py 文件相同的目录(相同的文件夹)中、
caesarCipher.py将导人这个模块。pyperclip.py模块如下:
凯撒密码的pyperclip.py模块:
"""
Pyperclip
A cross-platform clipboard module for Python, with copy & paste functions for plain text.
By Al Sweigart al@inventwithpython.com
BSD License
Usage:
import pyperclip
pyperclip.copy('The text to be copied to the clipboard.')
spam = pyperclip.paste()
if not pyperclip.is_available():
print("Copy functionality unavailable!")
On Windows, no additional modules are needed.
On Mac, the pyobjc module is used, falling back to the pbcopy and pbpaste cli
commands. (These commands should come with OS X.).
On Linux, install xclip or xsel via package manager. For example, in Debian:
sudo apt-get install xclip
sudo apt-get install xsel
Otherwise on Linux, you will need the gtk or PyQt5/PyQt4 modules installed.
gtk and PyQt4 modules are not available for Python 3,
and this module does not work with PyGObject yet.
Note: There seem sto be a way to get gtk on Python 3, according to:
https://askubuntu.com/questions/697397/python3-is-not-supporting-gtk-module
Cygwin is currently not supported.
Security Note: This module runs programs with these names:
- which
- where
- pbcopy
- pbpaste
- xclip
- xsel
- klipper
- qdbus
A malicious user could rename or add programs with these names, tricking
Pyperclip into running them with whatever permissions the Python process has.
"""
__version__ = '1.6.0'
import contextlib
import ctypes
import os
import platform
import subprocess
import sys
import time
import warnings
from ctypes import c_size_t, sizeof, c_wchar_p, get_errno, c_wchar
# `import PyQt4` sys.exit()s if DISPLAY is not in the environment.
# Thus, we need to detect the presence of $DISPLAY manually
# and not load PyQt4 if it is absent.
HAS_DISPLAY = os.getenv("DISPLAY", False)
EXCEPT_MSG = """
Pyperclip could not find a copy/paste mechanism for your system.
For more information, please visit https://pyperclip.readthedocs.io/en/latest/introduction.html#not-implemented-error """
PY2 = sys.version_info[0] == 2
STR_OR_UNICODE = unicode if PY2 else str
ENCODING = 'utf-8'
# The "which" unix command finds where a command is.
if platform.system() == 'Windows':
WHICH_CMD = 'where'
else:
WHICH_CMD = 'which'
def _executable_exists(name):
return subprocess.call([WHICH_CMD, name],
stdout=subprocess.PIPE, stderr=subprocess.PIPE) == 0
# Exceptions
class PyperclipException(RuntimeError):
pass
class PyperclipWindowsException(PyperclipException):
def __init__(self, message):
message += " (%s)" % ctypes.WinError()
super(PyperclipWindowsException, self).__init__(message)
def init_osx_pbcopy_clipboard():
def copy_osx_pbcopy(text):
p = subprocess.Popen(['pbcopy', 'w'],
stdin=subprocess.PIPE, close_fds=True)
p.communicate(input=text.encode(ENCODING))
def paste_osx_pbcopy():
p = subprocess.Popen(['pbpaste', 'r'],
stdout=subprocess.PIPE, close_fds=True)
stdout, stderr = p.communicate()
return stdout.decode(ENCODING)
return copy_osx_pbcopy, paste_osx_pbcopy
def init_osx_pyobjc_clipboard():
def copy_osx_pyobjc(text):
'''Copy string argument to clipboard'''
newStr = Foundation.NSString.stringWithString_(text).nsstring()
newData = newStr.dataUsingEncoding_(Foundation.NSUTF8StringEncoding)
board = AppKit.NSPasteboard.generalPasteboard()
board.declareTypes_owner_([AppKit.NSStringPboardType], None)
board.setData_forType_(newData, AppKit.NSStringPboardType)
def paste_osx_pyobjc():
"Returns contents of clipboard"
board = AppKit.NSPasteboard.generalPasteboard()
content = board.stringForType_(AppKit.NSStringPboardType)
return content
return copy_osx_pyobjc, paste_osx_pyobjc
def init_gtk_clipboard():
global gtk
import gtk
def copy_gtk(text):
global cb
cb = gtk.Clipboard()
cb.set_text(text)
cb.store()
def paste_gtk():
clipboardContents = gtk.Clipboard().wait_for_text()
# for python 2, returns None if the clipboard is blank.
if clipboardContents is None:
return ''
else:
return clipboardContents
return copy_gtk, paste_gtk
def init_qt_clipboard():
global QApplication
# $DISPLAY should exist
# Try to import from qtpy, but if that fails try PyQt5 then PyQt4
try:
from qtpy.QtWidgets import QApplication
except:
try:
from PyQt5.QtWidgets import QApplication
except:
from PyQt4.QtGui import QApplication
app = QApplication.instance()
if app is None:
app = QApplication([])
def copy_qt(text):
cb = app.clipboard()
cb.setText(text)
def paste_qt():
cb = app.clipboard()
return STR_OR_UNICODE(cb.text())
return copy_qt, paste_qt
def init_xclip_clipboard():
DEFAULT_SELECTION='c'
PRIMARY_SELECTION='p'
def copy_xclip(text, primary=False):
selection=DEFAULT_SELECTION
if primary:
selection=PRIMARY_SELECTION
p = subprocess.Popen(['xclip', '-selection', selection],
stdin=subprocess.PIPE, close_fds=True)
p.communicate(input=text.encode(ENCODING))
def paste_xclip(primary=False):
selection=DEFAULT_SELECTION
if primary:
selection=PRIMARY_SELECTION
p = subprocess.Popen(['xclip', '-selection', selection, '-o'],
stdout=subprocess.PIPE,
stderr=subprocess.PIPE,
close_fds=True)
stdout, stderr = p.communicate()
# Intentionally ignore extraneous output on stderr when clipboard is empty
return stdout.decode(ENCODING)
return copy_xclip, paste_xclip
def init_xsel_clipboard():
DEFAULT_SELECTION='-b'
PRIMARY_SELECTION='-p'
def copy_xsel(text, primary=False):
selection_flag = DEFAULT_SELECTION
if primary:
selection_flag = PRIMARY_SELECTION
p = subprocess.Popen(['xsel', selection_flag, '-i'],
stdin=subprocess.PIPE, close_fds=True)
p.communicate(input=text.encode(ENCODING))
def paste_xsel(primary=False):
selection_flag = DEFAULT_SELECTION
if primary:
selection_flag = PRIMARY_SELECTION
p = subprocess.Popen(['xsel', selection_flag, '-o'],
stdout=subprocess.PIPE, close_fds=True)
stdout, stderr = p.communicate()
return stdout.decode(ENCODING)
return copy_xsel, paste_xsel
def init_klipper_clipboard():
def copy_klipper(text):
p = subprocess.Popen(
['qdbus', 'org.kde.klipper', '/klipper', 'setClipboardContents',
text.encode(ENCODING)],
stdin=subprocess.PIPE, close_fds=True)
p.communicate(input=None)
def paste_klipper():
p = subprocess.Popen(
['qdbus', 'org.kde.klipper', '/klipper', 'getClipboardContents'],
stdout=subprocess.PIPE, close_fds=True)
stdout, stderr = p.communicate()
# Workaround for https://bugs.kde.org/show_bug.cgi?id=342874
# TODO: https://github.com/asweigart/pyperclip/issues/43
clipboardContents = stdout.decode(ENCODING)
# even if blank, Klipper will append a newline at the end
assert len(clipboardContents) > 0
# make sure that newline is there
assert clipboardContents.endswith('\n')
if clipboardContents.endswith('\n'):
clipboardContents = clipboardContents[:-1]
return clipboardContents
return copy_klipper, paste_klipper
def init_dev_clipboard_clipboard():
def copy_dev_clipboard(text):
if text == '':
warnings.warn('Pyperclip cannot copy a blank string to the clipboard on Cygwin. This is effectively a no-op.')
if '\r' in text:
warnings.warn('Pyperclip cannot handle \\r characters on Cygwin.')
fo = open('/dev/clipboard', 'wt')
fo.write(text)
fo.close()
def paste_dev_clipboard():
fo = open('/dev/clipboard', 'rt')
content = fo.read()
fo.close()
return content
return copy_dev_clipboard, paste_dev_clipboard
def init_no_clipboard():
class ClipboardUnavailable(object):
def __call__(self, *args, **kwargs):
raise PyperclipException(EXCEPT_MSG)
if PY2:
def __nonzero__(self):
return False
else:
def __bool__(self):
return False
return ClipboardUnavailable(), ClipboardUnavailable()
# Windows-related clipboard functions:
class CheckedCall(object):
def __init__(self, f):
super(CheckedCall, self).__setattr__("f", f)
def __call__(self, *args):
ret = self.f(*args)
if not ret and get_errno():
raise PyperclipWindowsException("Error calling " + self.f.__name__)
return ret
def __setattr__(self, key, value):
setattr(self.f, key, value)
def init_windows_clipboard():
global HGLOBAL, LPVOID, DWORD, LPCSTR, INT, HWND, HINSTANCE, HMENU, BOOL, UINT, HANDLE
from ctypes.wintypes import (HGLOBAL, LPVOID, DWORD, LPCSTR, INT, HWND,
HINSTANCE, HMENU, BOOL, UINT, HANDLE)
windll = ctypes.windll
msvcrt = ctypes.CDLL('msvcrt')
safeCreateWindowExA = CheckedCall(windll.user32.CreateWindowExA)
safeCreateWindowExA.argtypes = [DWORD, LPCSTR, LPCSTR, DWORD, INT, INT,
INT, INT, HWND, HMENU, HINSTANCE, LPVOID]
safeCreateWindowExA.restype = HWND
safeDestroyWindow = CheckedCall(windll.user32.DestroyWindow)
safeDestroyWindow.argtypes = [HWND]
safeDestroyWindow.restype = BOOL
OpenClipboard = windll.user32.OpenClipboard
OpenClipboard.argtypes = [HWND]
OpenClipboard.restype = BOOL
safeCloseClipboard = CheckedCall(windll.user32.CloseClipboard)
safeCloseClipboard.argtypes = []
safeCloseClipboard.restype = BOOL
safeEmptyClipboard = CheckedCall(windll.user32.EmptyClipboard)
safeEmptyClipboard.argtypes = []
safeEmptyClipboard.restype = BOOL
safeGetClipboardData = CheckedCall(windll.user32.GetClipboardData)
safeGetClipboardData.argtypes = [UINT]
safeGetClipboardData.restype = HANDLE
safeSetClipboardData = CheckedCall(windll.user32.SetClipboardData)
safeSetClipboardData.argtypes = [UINT, HANDLE]
safeSetClipboardData.restype = HANDLE
safeGlobalAlloc = CheckedCall(windll.kernel32.GlobalAlloc)
safeGlobalAlloc.argtypes = [UINT, c_size_t]
safeGlobalAlloc.restype = HGLOBAL
safeGlobalLock = CheckedCall(windll.kernel32.GlobalLock)
safeGlobalLock.argtypes = [HGLOBAL]
safeGlobalLock.restype = LPVOID
safeGlobalUnlock = CheckedCall(windll.kernel32.GlobalUnlock)
safeGlobalUnlock.argtypes = [HGLOBAL]
safeGlobalUnlock.restype = BOOL
wcslen = CheckedCall(msvcrt.wcslen)
wcslen.argtypes = [c_wchar_p]
wcslen.restype = UINT
GMEM_MOVEABLE = 0x0002
CF_UNICODETEXT = 13
@contextlib.contextmanager
def window():
"""
Context that provides a valid Windows hwnd.
"""
# we really just need the hwnd, so setting "STATIC"
# as predefined lpClass is just fine.
hwnd = safeCreateWindowExA(0, b"STATIC", None, 0, 0, 0, 0, 0,
None, None, None, None)
try:
yield hwnd
finally:
safeDestroyWindow(hwnd)
@contextlib.contextmanager
def clipboard(hwnd):
"""
Context manager that opens the clipboard and prevents
other applications from modifying the clipboard content.
"""
# We may not get the clipboard handle immediately because
# some other application is accessing it (?)
# We try for at least 500ms to get the clipboard.
t = time.time() + 0.5
success = False
while time.time() < t:
success = OpenClipboard(hwnd)
if success:
break
time.sleep(0.01)
if not success:
raise PyperclipWindowsException("Error calling OpenClipboard")
try:
yield
finally:
safeCloseClipboard()
def copy_windows(text):
# This function is heavily based on
# http://msdn.com/ms649016#_win32_Copying_Information_to_the_Clipboard
with window() as hwnd:
# http://msdn.com/ms649048
# If an application calls OpenClipboard with hwnd set to NULL,
# EmptyClipboard sets the clipboard owner to NULL;
# this causes SetClipboardData to fail.
# => We need a valid hwnd to copy something.
with clipboard(hwnd):
safeEmptyClipboard()
if text:
# http://msdn.com/ms649051
# If the hMem parameter identifies a memory object,
# the object must have been allocated using the
# function with the GMEM_MOVEABLE flag.
count = wcslen(text) + 1
handle = safeGlobalAlloc(GMEM_MOVEABLE,
count * sizeof(c_wchar))
locked_handle = safeGlobalLock(handle)
ctypes.memmove(c_wchar_p(locked_handle), c_wchar_p(text), count * sizeof(c_wchar))
safeGlobalUnlock(handle)
safeSetClipboardData(CF_UNICODETEXT, handle)
def paste_windows():
with clipboard(None):
handle = safeGetClipboardData(CF_UNICODETEXT)
if not handle:
# GetClipboardData may return NULL with errno == NO_ERROR
# if the clipboard is empty.
# (Also, it may return a handle to an empty buffer,
# but technically that's not empty)
return ""
return c_wchar_p(handle).value
return copy_windows, paste_windows
# Automatic detection of clipboard mechanisms and importing is done in deteremine_clipboard():
def determine_clipboard():
'''
Determine the OS/platform and set the copy() and paste() functions
accordingly.
'''
global Foundation, AppKit, gtk, qtpy, PyQt4, PyQt5
# Setup for the CYGWIN platform:
if 'cygwin' in platform.system().lower(): # Cygwin has a variety of values returned by platform.system(), such as 'CYGWIN_NT-6.1'
# FIXME: pyperclip currently does not support Cygwin,
# see https://github.com/asweigart/pyperclip/issues/55
if os.path.exists('/dev/clipboard'):
warnings.warn('Pyperclip\'s support for Cygwin is not perfect, see https://github.com/asweigart/pyperclip/issues/55')
return init_dev_clipboard_clipboard()
# Setup for the WINDOWS platform:
elif os.name == 'nt' or platform.system() == 'Windows':
return init_windows_clipboard()
# Setup for the MAC OS X platform:
if os.name == 'mac' or platform.system() == 'Darwin':
try:
import Foundation # check if pyobjc is installed
import AppKit
except ImportError:
return init_osx_pbcopy_clipboard()
else:
return init_osx_pyobjc_clipboard()
# Setup for the LINUX platform:
if HAS_DISPLAY:
try:
import gtk # check if gtk is installed
except ImportError:
pass # We want to fail fast for all non-ImportError exceptions.
else:
return init_gtk_clipboard()
if _executable_exists("xclip"):
return init_xclip_clipboard()
if _executable_exists("xsel"):
return init_xsel_clipboard()
if _executable_exists("klipper") and _executable_exists("qdbus"):
return init_klipper_clipboard()
try:
# qtpy is a small abstraction layer that lets you write applications using a single api call to either PyQt or PySide.
# https://pypi.python.org/pypi/QtPy
import qtpy # check if qtpy is installed
except ImportError:
# If qtpy isn't installed, fall back on importing PyQt4.
try:
import PyQt5 # check if PyQt5 is installed
except ImportError:
try:
import PyQt4 # check if PyQt4 is installed
except ImportError:
pass # We want to fail fast for all non-ImportError exceptions.
else:
return init_qt_clipboard()
else:
return init_qt_clipboard()
else:
return init_qt_clipboard()
return init_no_clipboard()
def set_clipboard(clipboard):
'''
Explicitly sets the clipboard mechanism. The "clipboard mechanism" is how
the copy() and paste() functions interact with the operating system to
implement the copy/paste feature. The clipboard parameter must be one of:
- pbcopy
- pbobjc (default on Mac OS X)
- gtk
- qt
- xclip
- xsel
- klipper
- windows (default on Windows)
- no (this is what is set when no clipboard mechanism can be found)
'''
global copy, paste
clipboard_types = {'pbcopy': init_osx_pbcopy_clipboard,
'pyobjc': init_osx_pyobjc_clipboard,
'gtk': init_gtk_clipboard,
'qt': init_qt_clipboard, # TODO - split this into 'qtpy', 'pyqt4', and 'pyqt5'
'xclip': init_xclip_clipboard,
'xsel': init_xsel_clipboard,
'klipper': init_klipper_clipboard,
'windows': init_windows_clipboard,
'no': init_no_clipboard}
if clipboard not in clipboard_types:
raise ValueError('Argument must be one of %s' % (', '.join([repr(_) for _ in clipboard_types.keys()])))
# Sets pyperclip's copy() and paste() functions:
copy, paste = clipboard_types[clipboard]()
def lazy_load_stub_copy(text):
'''
A stub function for copy(), which will load the real copy() function when
called so that the real copy() function is used for later calls.
This allows users to import pyperclip without having determine_clipboard()
automatically run, which will automatically select a clipboard mechanism.
This could be a problem if it selects, say, the memory-heavy PyQt4 module
but the user was just going to immediately call set_clipboard() to use a
different clipboard mechanism.
The lazy loading this stub function implements gives the user a chance to
call set_clipboard() to pick another clipboard mechanism. Or, if the user
simply calls copy() or paste() without calling set_clipboard() first,
will fall back on whatever clipboard mechanism that determine_clipboard()
automatically chooses.
'''
global copy, paste
copy, paste = determine_clipboard()
return copy(text)
def lazy_load_stub_paste():
'''
A stub function for paste(), which will load the real paste() function when
called so that the real paste() function is used for later calls.
This allows users to import pyperclip without having determine_clipboard()
automatically run, which will automatically select a clipboard mechanism.
This could be a problem if it selects, say, the memory-heavy PyQt4 module
but the user was just going to immediately call set_clipboard() to use a
different clipboard mechanism.
The lazy loading this stub function implements gives the user a chance to
call set_clipboard() to pick another clipboard mechanism. Or, if the user
simply calls copy() or paste() without calling set_clipboard() first,
will fall back on whatever clipboard mechanism that determine_clipboard()
automatically chooses.
'''
global copy, paste
copy, paste = determine_clipboard()
return paste()
def is_available():
return copy != lazy_load_stub_copy and paste != lazy_load_stub_paste
# Initially, copy() and paste() are set to lazy loading wrappers which will
# set `copy` and `paste` to real functions the first time they're used, unless
# set_clipboard() or determine_clipboard() is called first.
copy, paste = lazy_load_stub_copy, lazy_load_stub_paste
__all__ = ['copy', 'paste', 'set_clipboard', 'determine_clipboard']
1.首先引用pyperclip.py模块:
import pyperclip
2.定义变量message,message为要加密的字符串:
# The string to be encrypted
message = 'ILOVEYOU.'
3.将偏移设为3,即令key=3,设置为解密模式,并加入所有可加密的符号:
# The encryption key:
key = 3
mode = 'decrypt'
# Every possible symbol that can be encrypted:
SYMBOLS = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890 !?.'
4. translated储存信息的解密形式,仅加密/解密在symbols和SYMBOLS里共有的字符(串)
# Stores the encrypted/decrypted form of the message:
translated = ''
for symbol in message:
# Note: Only symbols in the `SYMBOLS` string can be encrypted/decrypted.
if symbol in SYMBOLS:
symbolIndex = SYMBOLS.find(symbol)
5.执行加密/解密并添加未加密/解密的字符:
# Perform encryption/decryption:
if mode == 'encrypt':
translatedIndex = symbolIndex + key
elif mode == 'decrypt':
translatedIndex = symbolIndex - key
# Handle wrap-around, if needed:
if translatedIndex >= len(SYMBOLS):
translatedIndex = translatedIndex - len(SYMBOLS)
elif translatedIndex < 0:
translatedIndex = translatedIndex + len(SYMBOLS)
translated = translated + SYMBOLS[translatedIndex]
6.输出translated字符串:
print(translated)
pyperclip.copy(translated)
来源:https://blog.csdn.net/weixin_52351575/article/details/120742012
0
投稿
猜你喜欢
- 介绍我们可以通过for循环来迭代list、tuple、dict、set、字符串,dict比较特殊dict的存储不是连续的,所以迭代(遍历)出
- 平时自己写了很多代码,但从没好好计算总共写了多少行,面试时被问起来,就傻了。。。闲来无事,写个python程序来统计下import os##
- php中主要用到的就是要用到fread()和fwirte()。而静态页面生成了之后,就会牵扯到修改的问题。这里可以用到正则匹配的方法来替换模
- 有的时候需要对python程序内存占用进行监控,这个时候可以用到psutil库,Anaconda中是自带的,如果import出错,可以用pi
- Cookie是一种发送到客户浏览器的文本串句柄,并保存在客户机硬盘上,可以用来在某个Web站点会话之间持久地保持数据。Request和Res
- 经纬度坐标转换最常见办法就是调用第三方 API,例如百度、高德地图等服务平台,提供了相应的功能接口,它们的这类技术已经非常成熟啦,准确稳定,
- 本文实例为大家分享了Python爬取最好大学网大学排名的具体代码,供大家参考,具体内容如下源代码:#-*-coding:utf-8-*- &
- bytes 和 bytearraybytes 和 bytearray 都是二进制世界的成员,用二进制的方式去理解才能看清他的本质。理解byt
- # -*- coding: cp936 -*-import socketfrom threading import Thread,activ
- 为什么要用jsonpath就跟为什么要用xpath一样,jsonpath的设计灵感来源于xpath。一个强大的json数据提取工具。让用户不
- 1.用CSS实现布局让我们一起来做一个页面,首先,我们需要一个布局。请使用CSS控制3个div,实现如下图的布局。考察应试者的基本布局知识—
- 起步这是许多开发者在项目初期要面临的一个普遍问题。要怎样来处理多用户类型。本文讲介绍对于不同场景和业务需求如何设计用户模型。为项目提供指导设
- 1.数据是什么?在 Python 以及其他所有面向对象编程语言中,类都是对数据的构成(状态)以及数据 能做什么(行为)的描述。由于类的使用者
- Django测试框架非常简单,首选方法是使用python标准库中的unittest模块。Writing testsDjango的单元测试使用
- 1、确认框架中安装了第三方alibabacoud控件实现代码如下上传过程中遇到任务问题,可以进行留言<?php namespace A
- 管理SQL Server内在的帐户和密码时,我们很容易认为这一切都相当的安全。但实际上并非如此。在这里,我们列出了一些对于SQL Serve
- 前言 在tensorflow的官方文档中得卷积神经网络一章,有一个使用cifar-10图片数据集的实验,搭建卷积神经网络倒不难,但是那个ci
- Oracle :NvlNVL函数:NVL函数是将NULL值的字段转换成默认字段输出。NVL(expr1,expr2)expr1,需要转换的字
- 一、安装我们知道selenium是桌面浏览器自动化操作工具(Web Browser Automation)appium是继承selenium
- 在CentOS上安装MySQL数据库服务器后,系统出于安全性考虑,缺省不支持用户通过非本机连接上数据库服务器,如果想让用户通过另外一台机器连