凯撒密码,凯撒加密解密.

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using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Linq;using System.Text;using System.Windows.Forms;namespace CaesarArithmetic{    public partial class Frm_Main : Form    {       int iShifting = 5;//默认偏移5        public Frm_Main()        {            InitializeComponent();        }        //获取字符的ASCII码        public int AscII(string str)        {            byte[] array = new byte[1];//创建字节数组            array = System.Text.Encoding.ASCII.GetBytes(str);//为字节数组赋值            int asciicode = (short)(array[0]);//获取字节数组的第一项            return asciicode;//返回字节数组的第一项        }        public string Caesar(string str)//凯撒加密算法的实现        {            char[] c = str.ToCharArray();//创建字符数组            string strCaesar = "";//定义一个变量，用来存储加密后的字符串            for (int i = 0; i < str.Length; i++)//遍历字符串中的每一个字符串            {                string ins = c[i].ToString();//记录遍历到的字符                int iIns = AscII(ins);                string outs = "";//定义一个变量，用来记录加密后的字符串                bool isChar = "0123456789abcdefghijklmnopqrstuvwxyz".Contains(ins.ToLower());//判断指定的字符串中是否包含遍历到的字符                bool isToUpperChar = isChar && (ins.ToUpper() == ins);//判断遍历到的字符是否是大写                ins = ins.ToLower();//将遍历到的字符转换为小写                if (isChar)//判断指定的字符串中是否包含遍历到的字符                {                   Console.WriteLine("ins = {0}, a = {1}, z={2},AscII(ins)={3} ", ins, AscII("a"), AscII("z"), AscII(ins));                   int offset = (AscII(ins) + iShifting - AscII("a")) % (AscII("z") - AscII("a") + 1);//获取字符的ASCII码                    Console.WriteLine("({0} + 5 - 97 ) % (122 - 97 + 1) ", AscII(ins) );                    Console.WriteLine("offset={0}",offset);                    outs = Convert.ToChar(offset + AscII("a")).ToString();//转换为字符并记录                    if (isToUpperChar)//判断是否大写                    {                        outs = outs.ToUpper();//全部转换为大写                    }                }                else                {                    outs = ins;//记录遍历的字符                }                strCaesar += outs;//添加到加密字符串中            }            return strCaesar;//返回加密后的字符串        }        private void button1_Click(object sender, EventArgs e)        {            string P_str_Code = textBox1.Text;//记录要加密的密码            textBox2.Text = Caesar(P_str_Code);//显示加密后的字符串        }        private void button2_Click(object sender, EventArgs e)        {           string P_str_Code = textBox2.Text;//记录要解密的密码           textBox2.Text = Caesar2(P_str_Code);//显示解密后的字符串        }        public string Caesar2(string str)//凯撒加密算法的实现        {           char[] c = str.ToCharArray();//创建字符数组           string strCaesar = "";//定义一个变量，用来存储加密后的字符串           for (int i = 0; i < str.Length; i++)//遍历字符串中的每一个字符串           {              string ins = c[i].ToString();//记录遍历到的字符              string outs = "";//定义一个变量，用来记录加密后的字符串              bool isChar = "0123456789abcdefghijklmnopqrstuvwxyz".Contains(ins.ToLower());//判断指定的字符串中是否包含遍历到的字符              bool isToUpperChar = isChar && (ins.ToUpper() == ins);//判断遍历到的字符是否是大写              ins = ins.ToLower();//将遍历到的字符转换为小写              if (isChar)//判断指定的字符串中是否包含遍历到的字符              {                 int iIns = AscII(ins);                 Console.WriteLine("ins = {0}, a = {1}, z={2} ", iIns, AscII("a"), AscII("z"));                 //int offset = (AscII(ins) + 5 - AscII("a")) % (AscII("z") - AscII("a") + 1);//获取字符的ASCII码                 //int offset = (AscII(ins) + 5 - AscII("a")) % (AscII("z") - AscII("a") + 1);//获取字符的ASCII码                 int offset = (AscII("z") + iShifting - AscII(ins)) % (AscII("z") - AscII("a") + 1);                                    Console.WriteLine("offset = {0} ", offset);                 //outs = Convert.ToChar(offset + AscII("a")).ToString();//转换为字符并记录                 outs = Convert.ToChar(AscII("z") - offset).ToString();//转换为字符并记录                 if (isToUpperChar)//判断是否大写                 {                    outs = outs.ToUpper();//全部转换为大写                 }                 Console.WriteLine("outs = {0}", outs);              }              else              {                 outs = ins;//记录遍历的字符              }              strCaesar += outs;//添加到加密字符串中           }           return strCaesar;//返回加密后的字符串        }    }}
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