使用对称加密与解密算法对文件加密与解密_对称加密算法实现一个类似pgp的文件加解密及完整性校验功能-优快云博客

本文链接：https://blog.youkuaiyun.com/niuyongjie/article/details/3733287

本文分享了一个简单的文件加密与解密程序实现过程，包括界面设计与核心代码。程序使用了CryptoHelper类来处理文件的加密解密操作，并提供不同算法的选择。此外，还介绍了密码强度评估方法。

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看了张子阳的博客，自己也看了一些资料，于是动手写了一个对文件加密与机密的小玩意，贴出来供大家参考，呵呵，可能对于高手来说，这个东西显的十分粗糙，希望大侠能够指点一二。

首先是程序的运行界面。

在该程序中自己写了一个类CryptoHelper，用来实现对文件的加密与解密操作。下面是这个类的源代码。

 
 using System;
using System.Collections.Generic;
using System.Text;
using System.Security.Cryptography;
using System.IO;
namespace PassWord
{
    class CryptoHelper
    {
        private SymmetricAlgorithm provider;
        private ICryptoTransform encryptor;
        private ICryptoTransform decryptor;
        private const int per_length = 100;
        /// <summary> 
        /// 返回每个加密方法的KEY的长度 
        /// </summary> 
        /// <param name="algrorithmName">算法名</param> 
        /// <returns>整型数组</returns> 
        /// 如果数组的第四个数据是0，那么 
        /// 数组的第一个数据是KEY的最少位 
        /// 数组的第二个数据是KEY的最大位，如果为0，说说明只支持一种位数 
        /// 数组的第三个数据是KEY的跳跃值 
        /// 如果数组的第四个数据是-1 
        /// 数组的第一个数据是KEY可以支持的第一种位数 
        /// 数组的第二个数据是KEY可以支持的第二种位数 
        /// 数组的第三个数据是KEY可以支持的第三种位数 
        public static int [] GetKeyLength(string algrorithmName)
        {
            int[] Int_Key = new int[4] { 0,0,0,0};           
            switch (algrorithmName)
            {
                case "DES":
                    {
                        Int_Key[0] = 64;
                        Int_Key[1] = 0;
                        Int_Key[2] = 0;
                        Int_Key[3] = 0;
                        return Int_Key;
                    }                   
                case "RC2":
                    {
                        Int_Key[0] = 40;
                        Int_Key[1] = 128;
                        Int_Key[2] = 8;
                        Int_Key[3] = 0;
                        return Int_Key;
                    } 
                case "Rijndael":
                    {
                        Int_Key[0] = 128;
                        Int_Key[1] = 192;
                        Int_Key[2] = 256;
                        Int_Key[3] = -1;
                        return Int_Key;
                    } 
                case "TripleDES":
                    {
                        Int_Key[0] = 128;
                        Int_Key[1] = 192;
                        Int_Key[2] = 64;
                        Int_Key[3] = 0;
                        return Int_Key;
                    } 
            }
            return Int_Key;
        }
        /// <summary> 
        /// 构造函数，用来生成具体的加密与解密的对象 
        /// </summary> 
        /// <param name="algrorithmName">加密或者解密的算法名称</param> 
        /// <param name="Key">加密或解密的密钥</param> 
        /// <param name="IV">加密或者解密的初始化向量</param> 
        public CryptoHelper(string algrorithmName, string Key, string IV)
        {
            provider = SymmetricAlgorithm.Create(algrorithmName);
            provider.Key = Encoding.UTF8.GetBytes(Key);
            provider.IV = Encoding.UTF8.GetBytes(IV);
            encryptor = provider.CreateEncryptor();
            decryptor = provider.CreateDecryptor();
        }
        ~CryptoHelper()
        {
            provider.Clear();
        }
        /// <summary> 
        /// 加密文件的方法 
        /// </summary> 
        /// <param name="inName">源文件名</param> 
        /// <param name="outName">目的文件名</param> 
        public void EncryptFile(String inName, String outName)
        {
            //建立文件流用来处理源文件与目的文件 
            FileStream fin = new FileStream(inName, FileMode.Open, FileAccess.Read);
            FileStream fout = new FileStream(outName, FileMode.OpenOrCreate, FileAccess.Write);
            fout.SetLength(0);
            //建立变量用来处理文件的读写 
            byte[] bin = new byte[per_length]; //加密的长度 
            long rdlen = 0;              //读取数据的总长度 
            long totlen = fin.Length;    //输入文件的总长度 
            int len;                    //每次读写数据的长度 
            
            CryptoStream encStream = new CryptoStream(fout,encryptor, CryptoStreamMode.Write);           
            //开始加密的过程 
            while (rdlen < totlen)
            {
                len = fin.Read(bin, 0, per_length);
                encStream.Write(bin, 0, len);
                rdlen = rdlen + len;               
            }
            encStream.Flush();
            encStream.Close();
            fout.Close();
            fin.Close();         
        }
        /// <summary> 
        /// 解密文件的算法 
        /// </summary> 
        /// <param name="inName">源文件名</param> 
        /// <param name="outName">目标文件名</param> 
        public void DecryptFile(String inName, String outName)
        {
            //建立文件流用来处理源文件与目的文件,源文件是加密后的文件 
            FileStream fin = new FileStream(inName, FileMode.Open, FileAccess.Read);
            FileStream fout = new FileStream(outName, FileMode.OpenOrCreate, FileAccess.Write);
            fout.SetLength(0);
            //建立变量用来处理文件的读写 
            byte[] bin = new byte[per_length]; //加密的长度 
            long rdlen = 0;              //读取数据的总长度 
            long totlen = fin.Length;    //输入文件的总长度 
            int len;                    //每次读写数据的长度 
            CryptoStream decStream = new CryptoStream(fout,decryptor, CryptoStreamMode.Write);
            //开始解密的过程 
            while (rdlen < totlen)
            {
                len = fin.Read(bin, 0, per_length);
                decStream.Write(bin, 0, len);
                rdlen = rdlen + len;
            }
            decStream.Flush();
            decStream.Close();            
            fout.Close();
            fin.Close();         
        }
    }
}
 

下面是界面的设计

下面是界面的一些设置的代码，这些代码由系统自己生成

 
 namespace PassWord
{
    partial class MainForm
    {
        /// <summary> 
        /// 必需的设计器变量。 
        /// </summary> 
        private System.ComponentModel.IContainer components = null;
        /// <summary> 
        /// 清理所有正在使用的资源。 
        /// </summary> 
        /// <param name="disposing">如果应释放托管资源，为 true；否则为 false。</param> 
        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {
                components.Dispose();
            }
            base.Dispose(disposing);
        } 
        #region Windows 窗体设计器生成的代码 
        /// <summary> 
        /// 设计器支持所需的方法 - 不要 
        /// 使用代码编辑器修改此方法的内容。 
        /// </summary> 
        private void InitializeComponent()
        {
            this.components = new System.ComponentModel.Container();
            System.ComponentModel.ComponentResourceManager resources = new System.ComponentModel.ComponentResourceManager(typeof(MainForm));
            this.pass_cb_style = new System.Windows.Forms.ComboBox();
            this.label1 = new System.Windows.Forms.Label();
            this.pass_tb_first = new System.Windows.Forms.TextBox();
            this.pass_tb_second = new System.Windows.Forms.TextBox();
            this.label2 = new System.Windows.Forms.Label();
            this.label3 = new System.Windows.Forms.Label();
            this.pass_but_encrty = new System.Windows.Forms.Button();
            this.pass_but_decrty = new System.Windows.Forms.Button();
            this.del_file_checkBox = new System.Windows.Forms.CheckBox();
            this.label4 = new System.Windows.Forms.Label();
            this.timer1 = new System.Windows.Forms.Timer(this.components);
            this.label5 = new System.Windows.Forms.Label();
            this.SuspendLayout();
            //  
            // pass_cb_style 
            //  
            this.pass_cb_style.BackColor = System.Drawing.SystemColors.InactiveCaptionText;
            this.pass_cb_style.DropDownStyle = System.Windows.Forms.ComboBoxStyle.DropDownList;
            this.pass_cb_style.Font = new System.Drawing.Font("Times New Roman", 15F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(0)));
            this.pass_cb_style.FormattingEnabled = true;
            this.pass_cb_style.Items.AddRange(new object[] {
            "DES",
            "RC2",
            "Rijndael",
            "TripleDES"});
            this.pass_cb_style.Location = new System.Drawing.Point(174, 16);
            this.pass_cb_style.Name = "pass_cb_style";
            this.pass_cb_style.Size = new System.Drawing.Size(167, 30);
            this.pass_cb_style.TabIndex = 0;
            this.pass_cb_style.SelectedIndexChanged += new System.EventHandler(this.pass_cb_style_SelectedIndexChanged);
            //  
            // label1 
            //  
            this.label1.AutoSize = true;
            this.label1.BackColor = System.Drawing.Color.Transparent;
            this.label1.Font = new System.Drawing.Font("楷体_GB2312", 15F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(134)));
            this.label1.Location = new System.Drawing.Point(18, 20);
            this.label1.Name = "label1";
            this.label1.Size = new System.Drawing.Size(149, 20);
            this.label1.TabIndex = 1;
            this.label1.Text = "选择加密的算法";
            //  
            // pass_tb_first 
            //  
            this.pass_tb_first.Font = new System.Drawing.Font("Times New Roman", 15F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(0)));
            this.pass_tb_first.Location = new System.Drawing.Point(174, 71);
            this.pass_tb_first.Name = "pass_tb_first";
            this.pass_tb_first.PasswordChar = '*';
            this.pass_tb_first.Size = new System.Drawing.Size(167, 30);
            this.pass_tb_first.TabIndex = 2;
            this.pass_tb_first.Leave += new System.EventHandler(this.pass_tb_first_Leave);
            this.pass_tb_first.KeyUp += new System.Windows.Forms.KeyEventHandler(this.pass_tb_first_KeyUp);
            this.pass_tb_first.Enter += new System.EventHandler(this.pass_tb_first_Enter);
            //  
            // pass_tb_second 
            //  
            this.pass_tb_second.Font = new System.Drawing.Font("Times New Roman", 15F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(0)));
            this.pass_tb_second.Location = new System.Drawing.Point(176, 164);
            this.pass_tb_second.Name = "pass_tb_second";
            this.pass_tb_second.PasswordChar = '*';
            this.pass_tb_second.Size = new System.Drawing.Size(165, 30);
            this.pass_tb_second.TabIndex = 3;
            this.pass_tb_second.Leave += new System.EventHandler(this.pass_tb_second_Leave);
            this.pass_tb_second.KeyUp += new System.Windows.Forms.KeyEventHandler(this.pass_tb_second_KeyUp);
            //  
            // label2 
            //  
            this.label2.AutoSize = true;
            this.label2.BackColor = System.Drawing.Color.Transparent;
            this.label2.Font = new System.Drawing.Font("楷体_GB2312", 15F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(134)));
            this.label2.Location = new System.Drawing.Point(18, 76);
            this.label2.Name = "label2";
            this.label2.Size = new System.Drawing.Size(129, 20);
            this.label2.TabIndex = 4;
            this.label2.Text = "初次输入密码";
            //  
            // label3 
            //  
            this.label3.AutoSize = true;
            this.label3.BackColor = System.Drawing.Color.Transparent;
            this.label3.Font = new System.Drawing.Font("楷体_GB2312", 15F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(134)));
            this.label3.Location = new System.Drawing.Point(18, 169);
            this.label3.Name = "label3";
            this.label3.Size = new System.Drawing.Size(129, 20);
            this.label3.TabIndex = 5;
            this.label3.Text = "再次输入密码";
            //  
            // pass_but_encrty 
            //  
            this.pass_but_encrty.Font = new System.Drawing.Font("楷体_GB2312", 15F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(134)));
            this.pass_but_encrty.ForeColor = System.Drawing.Color.Red;
            this.pass_but_encrty.Location = new System.Drawing.Point(40, 212);
            this.pass_but_encrty.Name = "pass_but_encrty";
            this.pass_but_encrty.Size = new System.Drawing.Size(77, 34);
            this.pass_but_encrty.TabIndex = 6;
            this.pass_but_encrty.Text = "加密";
            this.pass_but_encrty.UseVisualStyleBackColor = true;
            this.pass_but_encrty.Click += new System.EventHandler(this.pass_but_encrty_Click);
            //  
            // pass_but_decrty 
            //  
            this.pass_but_decrty.Font = new System.Drawing.Font("楷体_GB2312", 15F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(134)));
            this.pass_but_decrty.ForeColor = System.Drawing.Color.Lime;
            this.pass_but_decrty.Location = new System.Drawing.Point(201, 212);
            this.pass_but_decrty.Name = "pass_but_decrty";
            this.pass_but_decrty.Size = new System.Drawing.Size(77, 34);
            this.pass_but_decrty.TabIndex = 7;
            this.pass_but_decrty.Text = "解密";
            this.pass_but_decrty.UseVisualStyleBackColor = true;
            this.pass_but_decrty.Click += new System.EventHandler(this.pass_but_decrty_Click);
            //  
            // del_file_checkBox 
            //  
            this.del_file_checkBox.AutoSize = true;
            this.del_file_checkBox.BackColor = System.Drawing.Color.Transparent;
            this.del_file_checkBox.Font = new System.Drawing.Font("楷体_GB2312", 15F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(134)));
            this.del_file_checkBox.Location = new System.Drawing.Point(40, 269);
            this.del_file_checkBox.Name = "del_file_checkBox";
            this.del_file_checkBox.Size = new System.Drawing.Size(128, 24);
            this.del_file_checkBox.TabIndex = 8;
            this.del_file_checkBox.Text = "删除源文件";
            this.del_file_checkBox.UseVisualStyleBackColor = false;
            //  
            // label4 
            //  
            this.label4.AutoSize = true;
            this.label4.BackColor = System.Drawing.Color.Transparent;
            this.label4.Font = new System.Drawing.Font("楷体_GB2312", 15F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(134)));
            this.label4.Location = new System.Drawing.Point(18, 119);
            this.label4.Name = "label4";
            this.label4.Size = new System.Drawing.Size(119, 20);
            this.label4.TabIndex = 10;
            this.label4.Text = "密 码 强 度";
            //  
            // timer1 
            //  
            this.timer1.Interval = 500;
            this.timer1.Tick += new System.EventHandler(this.timer1_Tick);
            //  
            // label5 
            //  
            this.label5.AutoSize = true;
            this.label5.BackColor = System.Drawing.Color.White;
            this.label5.Font = new System.Drawing.Font("楷体_GB2312", 15F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(134)));
            this.label5.ForeColor = System.Drawing.Color.Red;
            this.label5.Location = new System.Drawing.Point(172, 119);
            this.label5.Name = "label5";
            this.label5.Size = new System.Drawing.Size(69, 20);
            this.label5.TabIndex = 11;
            this.label5.Text = "非常弱";
            //  
            // MainForm 
            //  
            this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 12F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.BackColor = System.Drawing.SystemColors.InactiveCaptionText;
            this.BackgroundImage = ((System.Drawing.Image)(resources.GetObject("$this.BackgroundImage")));
            this.BackgroundImageLayout = System.Windows.Forms.ImageLayout.Stretch;
            this.ClientSize = new System.Drawing.Size(366, 314);
            this.Controls.Add(this.label5);
            this.Controls.Add(this.label4);
            this.Controls.Add(this.del_file_checkBox);
            this.Controls.Add(this.pass_but_decrty);
            this.Controls.Add(this.pass_but_encrty);
            this.Controls.Add(this.label3);
            this.Controls.Add(this.label2);
            this.Controls.Add(this.pass_tb_second);
            this.Controls.Add(this.pass_tb_first);
            this.Controls.Add(this.label1);
            this.Controls.Add(this.pass_cb_style);
            this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedDialog;
            this.Icon = ((System.Drawing.Icon)(resources.GetObject("$this.Icon")));
            this.MaximizeBox = false;
            this.MinimizeBox = false;
            this.Name = "MainForm";
            this.Text = "加密与解密";
            this.Load += new System.EventHandler(this.Form1_Load);
            this.ResumeLayout(false);
            this.PerformLayout();
        } 
        #endregion 
        private System.Windows.Forms.ComboBox pass_cb_style;
        private System.Windows.Forms.Label label1;
        private System.Windows.Forms.TextBox pass_tb_first;
        private System.Windows.Forms.TextBox pass_tb_second;
        private System.Windows.Forms.Label label2;
        private System.Windows.Forms.Label label3;
        private System.Windows.Forms.Button pass_but_encrty;
        private System.Windows.Forms.Button pass_but_decrty;
        private System.Windows.Forms.CheckBox del_file_checkBox;
        private System.Windows.Forms.Label label4;
        private System.Windows.Forms.Timer timer1;
        private System.Windows.Forms.Label label5;
    }
}
 

其中控件的一些名称如表所示：

控件类别	控件名称	控件的用途
下拉式列表框	pass_cb_style	用来选择加密的算法
文本框	pass_tb_first	让用户输入密码
文本框	pass_tb_second	让用户输入密码，验证密码
按钮	pass_but_encrty	加密按钮
按钮	pass_but_decrty	解密按钮
标签	label5	指示密码强度
复选框	del_file_checkBox	是否删除源文件复选框

其中还放置了一个Timer控件，主要用来测试密码强度。

下面就是界面部分编制的代码了

 
 using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.IO;
namespace PassWord
{
    public partial class MainForm : Form
    {
        private string InputFile = string.Empty;
        private string OutputFile = string.Empty;
        private string algrorithmName = "DES";
        private int lowerChar = 0;//用来标志小写字母 
        private int upperChar = 0;//用来标志大写字母 
        private int numChar = 0;//用来标志数字 
        private int otherChar = 0;//用来标志其他字符 
        private int userPassLen = 0;
        private int userPassScore = 0;
        public MainForm()
        {
            InitializeComponent();
        }
        private void Form1_Load(object sender, EventArgs e)
        {
            
            pass_cb_style.Text = "DES";
            pass_but_encrty.Enabled = false;
            pass_but_decrty.Enabled = false;
            timer1.Enabled = false;
        }
        private void pass_but_encrty_Click(object sender, EventArgs e)
        {
            string Key = GetKey();
            string IV = GetIV();
            CryptoHelper encFile = new CryptoHelper(algrorithmName, Key, IV);
            GetIOFileName();
            if (InputFile != null && OutputFile != null)
            {
                try
                {
                    encFile.EncryptFile(InputFile, OutputFile);
                    MessageBox.Show("加密成功！！！", "恭喜！成功", MessageBoxButtons.OK, MessageBoxIcon.Information);
                    if (del_file_checkBox.Checked == true)
                        DeleteFile(InputFile);
                }
                catch
                {
                    MessageBox.Show("加密失败", "十分遗憾", MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
            }
        }
        private void pass_but_decrty_Click(object sender, EventArgs e)
        {
            string Key = GetKey();
            string IV = GetIV();
            CryptoHelper decFile = new CryptoHelper(algrorithmName, Key, IV);
            GetIOFileName();
            if (InputFile != null && OutputFile != null)
            {
                try
                {
                    decFile.DecryptFile(InputFile, OutputFile);
                    MessageBox.Show("解密成功！！！", "恭喜！成功", MessageBoxButtons.OK, MessageBoxIcon.Information);
                    if (del_file_checkBox.Checked == true)
                        DeleteFile(InputFile);
                }
                catch
                {
                    MessageBox.Show("解密失败", "十分遗憾", MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
            }
        }
        /// <summary> 
        /// 删除文件的函数 
        /// </summary> 
        /// <param name="filename">文件名</param> 
        public void DeleteFile(string filename)
        {
            try
            {
                File.Delete(filename);
            }
            catch (Exception e)
            {
                MessageBox.Show(e.ToString());
            }
        }
        /// <summary> 
        /// 得到输入/输出的文件名 
        /// </summary> 
        public void GetIOFileName()
        {
            OpenFileDialog openFile = new OpenFileDialog();
            openFile.Filter = "All files (*.*)|*.*";
            openFile.Title = "请你选择源文件";
            if (openFile.ShowDialog() == DialogResult.OK)
            {
                InputFile = openFile.FileName;
                SaveFileDialog saveFile = new SaveFileDialog();
                saveFile.Filter = "All files (*.*)|*.*";
                saveFile.Title = "请你选择目标文件";
                if (saveFile.ShowDialog() == DialogResult.OK)
                {
                    OutputFile = saveFile.FileName;
                    if (OutputFile == InputFile)
                    {
                        OutputFile = null;
                        MessageBox.Show("源文件不能与目标文件为同一个文件", "错误", MessageBoxButtons.OK);
                    }
                }
                else
                    OutputFile = null;
            }
            else
                InputFile = null;
        }
        /// <summary> 
        /// 得到算法名称，默认为DES 
        /// </summary> 
        /// <param name="sender"></param> 
        /// <param name="e"></param> 
        private void pass_cb_style_SelectedIndexChanged(object sender, EventArgs e)
        {
            algrorithmName = pass_cb_style.Text;
        }
        /// <summary> 
        /// 设置密码强度 
        /// </summary> 
        /// <param name="sender"></param> 
        /// <param name="e"></param> 
        private void pass_tb_first_KeyUp(object sender, KeyEventArgs e)
        {            
        }
        private void pass_tb_second_Leave(object sender, EventArgs e)
        {
            if (pass_tb_first.Text != pass_tb_second.Text)
            {
                MessageBox.Show("两次输入的密码不一致", "错误", MessageBoxButtons.OK, MessageBoxIcon.Error);
                pass_tb_second.Text = "";
            }
        }
        private void pass_tb_second_KeyUp(object sender, KeyEventArgs e)
        {
            if (pass_tb_first.Text == pass_tb_second.Text)
            {
                pass_but_decrty.Enabled = true;
                pass_but_encrty.Enabled = true;
            }
            else
            {
                pass_but_decrty.Enabled = false;
                pass_but_encrty.Enabled = false;
            }
        }
        /// <summary> 
        /// 得到密码 
        /// </summary> 
        /// <returns></returns> 
        private string GetKey()
        {
            string passWord = pass_tb_first.Text;
            int[] LegalLength = new int[4];
            LegalLength = CryptoHelper.GetKeyLength(algrorithmName);
            int plength = passWord.Length;
            switch (algrorithmName)
            {
                case "DES":
                    {
                        if (plength == LegalLength[0] / 8)
                            passWord = pass_tb_first.Text;
                        if (plength > LegalLength[0] / 8)
                            passWord = pass_tb_first.Text.Substring(0, 8);
                        if (plength < LegalLength[0] / 8)
                            passWord = RepeatStr(pass_tb_first.Text, 8);
                        break;
                    }
                case "RC2":
                    {
                        if (plength >= LegalLength[0] / 8 && plength <= LegalLength[1] / 8)
                            passWord = pass_tb_first.Text;
                        if (plength > LegalLength[1] / 8)
                            passWord = pass_tb_first.Text.Substring(0, 16);
                        if (plength < LegalLength[0] / 8)
                            passWord = RepeatStr(pass_tb_first.Text, 5);
                        break;
                    }
                case "TripleDES":
                    {
                        if (plength >= LegalLength[0] / 8 && plength <= LegalLength[1] / 8)
                        {
                            passWord = pass_tb_first.Text;
                            if (plength % 2 != 0)
                            {
                                passWord += passWord.Substring(0, 1);
                                plength = passWord.Length;
                            }
                        }
                        if (plength > LegalLength[1] / 8)
                            passWord = pass_tb_first.Text.Substring(0, 24);
                        if (plength < LegalLength[0] / 8)
                            passWord = RepeatStr(pass_tb_first.Text, 16);
                        break;
                    }
                case "Rijndael":
                    {
                        passWord = pass_tb_first.Text;
                        if (plength < LegalLength[0] / 8)
                            passWord = RepeatStr(passWord, 16);
                        if (plength < LegalLength[1] / 8)
                            passWord = RepeatStr(passWord, 24);
                        if (plength < LegalLength[2] / 8)
                            passWord = RepeatStr(passWord, 32);
                        break;
                    }
            }
            return passWord;
        }
        /// <summary> 
        /// 得到加密的块 
        /// </summary> 
        /// <returns>符合要求的块</returns> 
        private string GetIV()
        {
            string iv = pass_tb_first.Text;
            int len = iv.Length;
            switch (algrorithmName)
            {
                case "Rijndael":
                    {
                        if (len < 16)
                            iv = RepeatStr(pass_tb_first.Text, 16);
                        else
                            iv = pass_tb_first.Text.Substring(0, 16);
                        break;
                    }
                default:
                    {
                        if (len < 8)
                            iv = RepeatStr(pass_tb_first.Text, 8);
                        else
                            iv = pass_tb_first.Text.Substring(0, 8);
                        break;
                    }
            }
            return iv;
        }
        /// <summary> 
        /// 重复字符串到指定的长度 
        /// </summary> 
        /// <param name="str">字符串</param> 
        /// <param name="length">指定长度</param> 
        /// <returns>符合要求字符串</returns> 
        private string RepeatStr(string str, int length)
        {
            int lenold = str.Length;
            string temp = str;
            int len = lenold;
            if (len >= length)
                return str;
            while (len < length)
            {
                if (length - len < lenold)
                {
                    str += str.Substring(0, length - len);
                    len += length - len;
                }
                else
                {
                    str += temp;
                    len += lenold;
                }
            }
            return str;
        }
        private void timer1_Tick(object sender, EventArgs e)
        {
            // 一、密码长度: 
            //5 分: 小于等于 4 个字符  
            //10 分: 5 到 7 字符  
            //25 分: 大于等于 8 个字符  
            //二、字母: 
            //0 分: 没有字母  
            //10 分: 全都是小（大）写字母  
            //20 分: 大小写混合字母  
            //三、数字: 
            //0 分: 没有数字  
            //10 分: 1 个数字  
            //20 分: 大于等于 3 个数字  
            //四、符号: 
            //0 分: 没有符号  
            //10 分: 1 个符号  
            //25 分: 大于 1 个符号  
            //五、奖励: 
            //2 分: 字母和数字  
            //3 分: 字母、数字和符号  
            //5 分: 大小写字母、数字和符号  
            //最后的评分标准: 
            //>= 90: 非常安全  
            //>= 80: 安全（Secure）  
            //>= 70: 非常强  
            //>= 60: 强（Strong）  
            //>= 50: 一般（Average）  
            //>= 25: 弱（Weak）  
            //>= 0: 非常弱  
            userPassScore = 0;
            userPassLen = 0;
            userPassLen=pass_tb_first.Text.Length;
            lowerChar = 0;
            upperChar = 0;
            numChar = 0;
            otherChar = 0;            
            foreach (char c in pass_tb_first.Text.ToCharArray())
            {
                if (Char.IsLower(c))
                {
                    lowerChar++;
                }
                if (Char.IsUpper(c))
                {
                    upperChar++;
                }
                if (Char.IsDigit(c))
                {
                    numChar++;
                }
                if (Char.IsSymbol(c) || Char.IsPunctuation(c) || Char.IsSeparator(c) || Char.IsWhiteSpace(c))
                {
                    otherChar++;
                }
            }
            //长度 
            if (userPassLen <= 4 && userPassLen!=0)
                userPassScore = 5;
            if (userPassLen >= 5 && userPassLen <= 7)
                userPassScore = 10;
            if (userPassLen >= 8)
                userPassScore = 25;
            if ((lowerChar != 0 || upperChar != 0) && (userPassLen == lowerChar || userPassLen == upperChar))
            {
                userPassScore += 10;
            }
            if ((lowerChar != 0 ||upperChar != 0 )&& (userPassLen != lowerChar || userPassLen != upperChar))
            {
                userPassScore += 20;
            }
            if (numChar != 0)
            {
                userPassScore += 10;
                if (numChar > 3)
                    userPassScore += 20;
            }
            if (otherChar != 0)
            {
                userPassScore += 10;
                if (otherChar > 3)
                    userPassScore += 25;
            }
            if (lowerChar != 0 && upperChar != 0 && numChar != 0 && otherChar != 0)
            {
                userPassScore += 5;
            }
            if(userPassScore<25)
                label5.Text = "非常弱";
            if (userPassScore >= 25 && userPassScore < 50)
            {
                label5.Text = "弱";
                label5.ForeColor = System.Drawing.Color.Red;
            }
            if (userPassScore >= 50 && userPassScore < 60)
            {
                label5.Text = "一般";
                label5.ForeColor = System.Drawing.Color.Blue;
            }
            if (userPassScore >= 60 && userPassScore < 70)
            {
                label5.Text = "强";
                label5.ForeColor = System.Drawing.Color.YellowGreen;
            }
            if (userPassScore >= 70 && userPassScore < 80)
            {
                label5.Text = "非常强";
                label5.ForeColor = System.Drawing.Color.LightGreen;
            }
            if (userPassScore >= 80 && userPassScore < 90)
            {
                label5.Text = "安全";
                label5.ForeColor = System.Drawing.Color.GreenYellow;
            }
            if (userPassScore >= 90)
            {
                label5.Text = "非常安全";
                label5.ForeColor = System.Drawing.Color.Green;
            }
        }
        private void pass_tb_first_Enter(object sender, EventArgs e)
        {
            timer1.Enabled = true;
        }
        private void pass_tb_first_Leave(object sender, EventArgs e)
        {
            timer1.Enabled = false;
        }
    }
}
 

最后的一点补充说明

加密算法名称	密钥位数（KEY）	初始化向量（IV）
DES	64位	64位
RC2	40位到128位，位数递增8	64位
Rijndael	128，192，256	128--256 每次递增64位
TripleDES	128位到192位	64位