.net名称空间System.Security.Cryptography下DESCryptoServiceProvider类为我们提供了加密和解密方法，我们只需少许代码便可实现加密和解密。
稍感不托的地方，如果不是自行加密的在解密时会报错。
使用注意事项，密钥64位，8个字符。
定义默认加密密钥
const string KEY_64 = "ChinabCd";
const string IV_64 = "ChinabCd";
加密
/// <summary>
/// 按指定键值进行加密
/// </summary>
/// <param name="strContent">要加密字符</param>
/// <param name="strKey">自定义键值</param>
/// <returns></returns> public static string EnCrypt(string strContent, string strKey) {
if (string.IsNullOrEmpty(strContent)) return string.Empty;
if (strKey.Length > ) strKey = strKey.Substring(, ); else strKey = KEY_64;
byte[] byKey = System.Text.ASCIIEncoding.ASCII.GetBytes(strKey);
byte[] byIV = System.Text.ASCIIEncoding.ASCII.GetBytes(IV_64); DESCryptoServiceProvider cryptoProvider = new DESCryptoServiceProvider();
int i = cryptoProvider.KeySize;
MemoryStream ms = new MemoryStream();
CryptoStream cst = new CryptoStream(ms, cryptoProvider.CreateEncryptor(byKey, byIV), CryptoStreamMode.Write); StreamWriter sw = new StreamWriter(cst);
sw.Write(strContent);
sw.Flush();
cst.FlushFinalBlock();
sw.Flush();
return Convert.ToBase64String(ms.GetBuffer(), , (int)ms.Length);
}
解密
/// <summary>
/// 按指定键值进行解密
/// </summary>
/// <param name="strContent">要解密字符</param>
/// <param name="strKey">加密时使用的键值</param>
/// <returns></returns>
public static string DeCrypt(string strContent, string strKey)
{
if (string.IsNullOrEmpty(strContent)) return string.Empty;
if (strKey.Length > ) strKey = strKey.Substring(, ); else strKey = KEY_64;
byte[] byKey = System.Text.ASCIIEncoding.ASCII.GetBytes(strKey);
byte[] byIV = System.Text.ASCIIEncoding.ASCII.GetBytes(IV_64); byte[] byEnc;
try
{
byEnc = Convert.FromBase64String(strContent);
}
catch
{
return null;
} DESCryptoServiceProvider cryptoProvider = new DESCryptoServiceProvider();
MemoryStream ms = new MemoryStream(byEnc);
CryptoStream cst = new CryptoStream(ms, cryptoProvider.CreateDecryptor(byKey, byIV), CryptoStreamMode.Read);
StreamReader sr = new StreamReader(cst);
return sr.ReadToEnd();
}