Key為八位字串

/// <summary>
/// DES加密字串
/// </summary>
/// <param name="pToEncrypt">待加密的字串</param>
/// <param name="sKey">加密金鑰,要求為8位</param>
/// <returns>加密成功返回加密後的字串，失敗返回源串</returns>
public static string DesEncrypt(string pToEncrypt, string sKey)
{
	 StringBuilder ret = new StringBuilder();
	 try
	 {
	     DESCryptoServiceProvider des = new DESCryptoServiceProvider();
	     byte[] inputByteArray = Encoding.Default.GetBytes(pToEncrypt);
	     des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
	     des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
	     MemoryStream ms = new MemoryStream();
	     CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(),CryptoStreamMode.Write);
	     cs.Write(inputByteArray, 0, inputByteArray.Length);
	     cs.FlushFinalBlock();
	     foreach (byte b in ms.ToArray())
	     {
	         ret.AppendFormat("{0:X2}", b);
	     }
	     return ret.ToString();
	 }
	 catch
	 {
	     return pToEncrypt;
	 }
}

/// <summary>
/// DES解密字串
/// </summary>
/// <param name="pToDecrypt">待解密的字串</param>
/// <param name="sKey">解密金鑰,要求為8位,和加密金鑰相同</param>
/// <returns>解密成功返回解密後的字串，失敗返源串</returns>
public static string DesDecrypt(string pToDecrypt, string sKey)
{
	 MemoryStream ms = new MemoryStream();
	 try
	 {
	     DESCryptoServiceProvider des = new DESCryptoServiceProvider();
	     byte[] inputByteArray = new byte[pToDecrypt.Length / 2];
	     for (int x = 0; x < pToDecrypt.Length / 2; x++)
	     {
	         int i = (Convert.ToInt32(pToDecrypt.Substring(x * 2, 2), 16));
	         inputByteArray[x] = (byte)i;
	     }
	     des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
	     des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
	     CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);
	     cs.Write(inputByteArray, 0, inputByteArray.Length);
	     cs.FlushFinalBlock();
	     return System.Text.Encoding.Default.GetString(ms.ToArray());
	 }
	 catch
	 {
	     return pToDecrypt;
	 }
}