C# 文件夹加密

可以加密文件内容，也可以对文件夹本身进行加密，本文对文件夹加密。

一、指定或生成一个密钥

  1）指定的密钥

 /// <summary>
 /// 密钥，这个密码可以随便指定
 /// </summary>
 public static string sSecretKey = "?a??64(?";

 2） 也可以生成密钥

/// <summary>
/// 生成一个64位的密钥
/// </summary>
/// <returns>string</returns>
public static string GenerateKey()
{
　　//创建对称算法的一个实例。自动生成的密钥和IV。
　　DESCryptoServiceProvider desCrypto = (DESCryptoServiceProvider)DESCryptoServiceProvider.Create();

    // 使用自动生成的密钥进行加密。
    return ASCIIEncoding.ASCII.GetString(desCrypto.Key);
 }

二、调用ZeroMemory 函数从内存中删除Key

///<summary>
/// 调用该函数从内存中删除的Key后使用
/// </summary>
[DllImport("KERNEL32.DLL", EntryPoint = "RtlZeroMemory")]
public static extern bool ZeroMemory(IntPtr Destination, int Length);

三、加密文件

/// <summary>
        /// 加密文件
        /// </summary>
        /// <param name="sInputFilename">待加密的文件的完整路径</param>
        /// <param name="sOutputFilename">加密后的文件的完整路径</param>
        public static void EncryptFile(string sInputFilename, string sOutputFilename)
        {
            FileStream fsInput = new FileStream(sInputFilename, FileMode.Open, FileAccess.Read);

            FileStream fsEncrypted = new FileStream(sOutputFilename, FileMode.Create, FileAccess.Write);
            DESCryptoServiceProvider DES = new DESCryptoServiceProvider();
            DES.Key = ASCIIEncoding.ASCII.GetBytes(sSecretKey);
            DES.IV = ASCIIEncoding.ASCII.GetBytes(sSecretKey);
            ICryptoTransform desencrypt = DES.CreateEncryptor();
            CryptoStream cryptostream = new CryptoStream(fsEncrypted, desencrypt, CryptoStreamMode.Write);

            byte[] bytearrayinput = new byte[fsInput.Length];
            fsInput.Read(bytearrayinput, 0, bytearrayinput.Length);
            cryptostream.Write(bytearrayinput, 0, bytearrayinput.Length);

            cryptostream.Flush();
            fsInput.Flush();
            fsEncrypted.Flush();
            cryptostream.Close();
            fsInput.Close();
            fsEncrypted.Close();
        }

四、解密文件

/// <summary>
        /// 解密文件
        /// </summary>
        /// <param name="sInputFilename">待解密的文件的完整路径</param>
        /// <param name="sOutputFilename">解密后的文件的完整路径</param>
        public static void DecryptFile(string sInputFilename, string sOutputFilename)
        {
            DESCryptoServiceProvider DES = new DESCryptoServiceProvider();
            DES.Key = ASCIIEncoding.ASCII.GetBytes(sSecretKey);
            DES.IV = ASCIIEncoding.ASCII.GetBytes(sSecretKey);

            FileStream fsread = new FileStream(sInputFilename, FileMode.Open, FileAccess.Read);
            ICryptoTransform desdecrypt = DES.CreateDecryptor();
            CryptoStream cryptostreamDecr = new CryptoStream(fsread, desdecrypt, CryptoStreamMode.Read);
            StreamWriter fsDecrypted = new StreamWriter(sOutputFilename);
            fsDecrypted.Write(new StreamReader(cryptostreamDecr).ReadToEnd());
            fsDecrypted.Flush();
            fsDecrypted.Close();
        }

五、完整代码

/// <summary>
    /// 文件加密
    /// </summary>
    public class FileSecretHelper
    {
        /// <summary>
        /// 密钥，这个密码可以随便指定
        /// </summary>
        public static string sSecretKey = "?a??64(?";

        /// <summary>
        /// 调用该函数从内存中删除的Key后使用
        /// </summary>
        [DllImport("KERNEL32.DLL", EntryPoint = "RtlZeroMemory")]
        public static extern bool ZeroMemory(IntPtr Destination, int Length);


        /// <summary>
        /// 生成一个64位的密钥
        /// </summary>
        /// <returns>string</returns>
        public static string GenerateKey()
        {
            //创建对称算法的一个实例。自动生成的密钥和IV。
            DESCryptoServiceProvider desCrypto = (DESCryptoServiceProvider)DESCryptoServiceProvider.Create();

            // 使用自动生成的密钥进行加密。
            return ASCIIEncoding.ASCII.GetString(desCrypto.Key);
        }

        /// <summary>
        /// 加密文件
        /// </summary>
        /// <param name="sInputFilename">待加密的文件的完整路径</param>
        /// <param name="sOutputFilename">加密后的文件的完整路径</param>
        public static void EncryptFile(string sInputFilename, string sOutputFilename)
        {
            FileStream fsInput = new FileStream(sInputFilename, FileMode.Open, FileAccess.Read);

            FileStream fsEncrypted = new FileStream(sOutputFilename, FileMode.Create, FileAccess.Write);
            DESCryptoServiceProvider DES = new DESCryptoServiceProvider();
            DES.Key = ASCIIEncoding.ASCII.GetBytes(sSecretKey);
            DES.IV = ASCIIEncoding.ASCII.GetBytes(sSecretKey);
            ICryptoTransform desencrypt = DES.CreateEncryptor();
            CryptoStream cryptostream = new CryptoStream(fsEncrypted, desencrypt, CryptoStreamMode.Write);

            byte[] bytearrayinput = new byte[fsInput.Length];
            fsInput.Read(bytearrayinput, 0, bytearrayinput.Length);
            cryptostream.Write(bytearrayinput, 0, bytearrayinput.Length);

            cryptostream.Flush();
            fsInput.Flush();
            fsEncrypted.Flush();
            cryptostream.Close();
            fsInput.Close();
            fsEncrypted.Close();
        }

        /// <summary>
        /// 解密文件
        /// </summary>
        /// <param name="sInputFilename">待解密的文件的完整路径</param>
        /// <param name="sOutputFilename">解密后的文件的完整路径</param>
        public static void DecryptFile(string sInputFilename, string sOutputFilename)
        {
            DESCryptoServiceProvider DES = new DESCryptoServiceProvider();
            DES.Key = ASCIIEncoding.ASCII.GetBytes(sSecretKey);
            DES.IV = ASCIIEncoding.ASCII.GetBytes(sSecretKey);

            FileStream fsread = new FileStream(sInputFilename, FileMode.Open, FileAccess.Read);
            ICryptoTransform desdecrypt = DES.CreateDecryptor();
            CryptoStream cryptostreamDecr = new CryptoStream(fsread, desdecrypt, CryptoStreamMode.Read);
            StreamWriter fsDecrypted = new StreamWriter(sOutputFilename);
            fsDecrypted.Write(new StreamReader(cryptostreamDecr).ReadToEnd());
            fsDecrypted.Flush();
            fsDecrypted.Close();
        }
    }