C#对字符和文件的加密解密类

转自: http://www.cnblogs.com/bluescreen/archive/2012/02/17/2355731.html 

public class strorfilepass    {
           ////// 初始化安全类
 ///public strorfilepass()
         {
             ///默认密码
             key = "www.qhjsw.net";
         }
         private string key; //默认密钥
 
         private byte[] sKey;
         private byte[] sIV;
 
         #region 加密字符串
         ////// 加密字符串
 //////输入字符串///密码，可以为""///输出加密后字符串public string EncryptString(string inputStr, string keyStr)
         {
             DESCryptoServiceProvider des = new DESCryptoServiceProvider();
             if (keyStr == "")
                 keyStr = key;
             byte[] inputByteArray = Encoding.Default.GetBytes(inputStr);
             byte[] keyByteArray = Encoding.Default.GetBytes(keyStr);
             SHA1 ha = new SHA1Managed();
             byte[] hb = ha.ComputeHash(keyByteArray);
             sKey = new byte[8];
             sIV = new byte[8];
             for (int i = 0; i < 8; i++)
                 sKey[i] = hb[i];
             for (int i = 8; i < 16; i++)
                 sIV[i - 8] = hb[i];
             des.Key = sKey;
             des.IV = sIV;
             MemoryStream ms = new MemoryStream();
             CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write);
             cs.Write(inputByteArray, 0, inputByteArray.Length);
             cs.FlushFinalBlock();
             StringBuilder ret = new StringBuilder();
             foreach (byte b in ms.ToArray())
             {
                 ret.AppendFormat("{0:X2}", b);
             }
             cs.Close();
             ms.Close();
             return ret.ToString();
         }
         ////// 解密字符串
 //////要解密的字符串///密钥///解密后的结果public string DecryptString(string inputStr, string keyStr)
         {
             DESCryptoServiceProvider des = new DESCryptoServiceProvider();
             if (keyStr == "")
                 keyStr = key;
             byte[] inputByteArray = new byte[inputStr.Length / 2];
             for (int x = 0; x < inputStr.Length / 2; x++)
             {
                 int i = (Convert.ToInt32(inputStr.Substring(x * 2, 2), 16));
                 inputByteArray[x] = (byte)i;
             }
             byte[] keyByteArray = Encoding.Default.GetBytes(keyStr);
             SHA1 ha = new SHA1Managed();
             byte[] hb = ha.ComputeHash(keyByteArray);
             sKey = new byte[8];
             sIV = new byte[8];
             for (int i = 0; i < 8; i++)
                 sKey[i] = hb[i];
             for (int i = 8; i < 16; i++)
                 sIV[i - 8] = hb[i];
             des.Key = sKey;
             des.IV = sIV;
             MemoryStream ms = new MemoryStream();
             CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);
             cs.Write(inputByteArray, 0, inputByteArray.Length);
             cs.FlushFinalBlock();
             StringBuilder ret = new StringBuilder();
             return System.Text.Encoding.Default.GetString(ms.ToArray());
         }
         #endregion
 
         #region 加密文件
         ////// 加密文件
 //////输入文件路径///加密后输出文件路径///密码，可以为""///public bool EncryptFile(string filePath, string savePath, string keyStr)
         {
             try
             {
                 DESCryptoServiceProvider des = new DESCryptoServiceProvider();
                 if (keyStr == "")
                     keyStr = key;
                 FileStream fs = File.OpenRead(filePath);
                 byte[] inputByteArray = new byte[fs.Length];
                 fs.Read(inputByteArray, 0, (int)fs.Length);
                 fs.Close();
                 byte[] keyByteArray = Encoding.Default.GetBytes(keyStr);
                 SHA1 ha = new SHA1Managed();
                 byte[] hb = ha.ComputeHash(keyByteArray);
                 sKey = new byte[8];
                 sIV = new byte[8];
                 for (int i = 0; i < 8; i++)
                     sKey[i] = hb[i];
                 for (int i = 8; i < 16; i++)
                     sIV[i - 8] = hb[i];
                 des.Key = sKey;
                 des.IV = sIV;
                 MemoryStream ms = new MemoryStream();
                 CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write);
                 cs.Write(inputByteArray, 0, inputByteArray.Length);
                 cs.FlushFinalBlock();
                 fs = File.OpenWrite(savePath);
                 foreach (byte b in ms.ToArray())
                 {
                     fs.WriteByte(b);
                 }
                 fs.Close();
                 cs.Close();
                 ms.Close();
                 return true;
             }
             catch{
                 return false;
             }
         }
         #endregion
 
         #region 解密文件
         ////// 解密文件
 //////输入文件路径///解密后输出文件路径///密码，可以为""///public bool DecryptFile(string filePath, string savePath, string keyStr)
         {
             try
             {
                 DESCryptoServiceProvider des = new DESCryptoServiceProvider();
                 if (keyStr == "")
                     keyStr = key;
                 FileStream fs = File.OpenRead(filePath);
                 byte[] inputByteArray = new byte[fs.Length];
                 fs.Read(inputByteArray, 0, (int)fs.Length);
                 fs.Close();
                 byte[] keyByteArray = Encoding.Default.GetBytes(keyStr);
                 SHA1 ha = new SHA1Managed();
                 byte[] hb = ha.ComputeHash(keyByteArray);
                 sKey = new byte[8];
                 sIV = new byte[8];
                 for (int i = 0; i < 8; i++)
                     sKey[i] = hb[i];
                 for (int i = 8; i < 16; i++)
                     sIV[i - 8] = hb[i];
                 des.Key = sKey;
                 des.IV = sIV;
                 MemoryStream ms = new MemoryStream();
                 CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);
                 cs.Write(inputByteArray, 0, inputByteArray.Length);
                 cs.FlushFinalBlock();
                 fs = File.OpenWrite(savePath);
                 foreach (byte b in ms.ToArray())
                 {
                     fs.WriteByte(b);
                 }
                 fs.Close();
                 cs.Close();
                 ms.Close();
 
                 return true;
             }
             catch {
                 return false;
             }
         }
         #endregion
         # region 大文件加密
         ////// 加密文件
 //////输入文件路径///加密后输出文件路径///密码，可以为""///public bool BEncryptFile(string filePath, string savePath, string keyStr)
         {
             try
             {
                 DESCryptoServiceProvider des = new DESCryptoServiceProvider();
                 if (keyStr == "")
                     keyStr = key;
                 FileStream fs = File.OpenRead(filePath);
                 byte[] inputByteArray = new byte[500];
                 long Myfilesize = fs.Length;
                 int Mycompletedsize = 0;
                 byte[] keyByteArray = Encoding.Default.GetBytes(keyStr);
                 SHA1 ha = new SHA1Managed();
                 byte[] hb = ha.ComputeHash(keyByteArray);
                 sKey = new byte[8];
                 sIV = new byte[8];
                 for (int i = 0; i < 8; i++)
                     sKey[i] = hb[i];
                 for (int i = 8; i < 16; i++)
                     sIV[i - 8] = hb[i];
                 des.Key = sKey;
                 des.IV = sIV;
                 FileStream ms = File.OpenWrite(savePath);
                 CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write);
                 while (Mycompletedsize < Myfilesize)
                 {
                     int length = fs.Read(inputByteArray, 0, 500);
                     cs.Write(inputByteArray, 0, length);
                     Mycompletedsize += length;
                 }
                 cs.FlushFinalBlock();
                 fs.Close();
                 fs.Dispose();
                 cs.Close();
                 cs.Dispose();
                 ms.Close();
                 ms.Dispose();
                 return true;
             }
             catch
             {
                 return false;
             }
         }
 
 
         ////// 解密文件
 //////输入文件路径///解密后输出文件路径///密码，可以为""///public bool BDecryptFile(string filePath, string savePath, string keyStr)
         {
             try
             {
                 DESCryptoServiceProvider des = new DESCryptoServiceProvider();
                 if (keyStr == "")
                     keyStr = key;
                 FileStream fs = File.OpenRead(filePath);
                 byte[] inputByteArray = new byte[500];
                 long Myfilesize = fs.Length;
                 int Mycompletedsize = 0;
                 byte[] keyByteArray = Encoding.Default.GetBytes(keyStr);
                 SHA1 ha = new SHA1Managed();
                 byte[] hb = ha.ComputeHash(keyByteArray);
                 sKey = new byte[8];
                 sIV = new byte[8];
                 for (int i = 0; i < 8; i++)
                     sKey[i] = hb[i];
                 for (int i = 8; i < 16; i++)
                     sIV[i - 8] = hb[i];
                 des.Key = sKey;
                 des.IV = sIV;
                 FileStream ms = File.OpenWrite(savePath);
                 CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);
                 while (Mycompletedsize < Myfilesize)
                 {
                     int length = fs.Read(inputByteArray, 0, 500);
                     cs.Write(inputByteArray, 0, length);
                     Mycompletedsize += length;
                 }
                 cs.FlushFinalBlock();
 
                 fs.Close();
                 fs.Dispose();
                 cs.Close();
                 cs.Dispose();
                 ms.Close();
                 ms.Dispose();
 
                 return true;
             }
             catch
             {
                 return false;
             }
         }
         #endregion
     }