C#加密与解密

/// <summary>
///  DEC   加密过程
/// </summary>
/// <param name="pToEncrypt">要加密的字符串</param>
/// <param name="sKey">密匙</param>
/// <returns></returns>
public static string Encrypt(string pToEncrypt, string sKey)
{
DESCryptoServiceProvider des = new DESCryptoServiceProvider();     //把字符串放到byte数组中

byte[] inputByteArray = Encoding.Default.GetBytes(pToEncrypt);

des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);     //建立加密对象的密钥和偏移量
des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);       //原文使用ASCIIEncoding.ASCII方法的GetBytes方法
MemoryStream ms = new MemoryStream();           //使得输入密码必须输入英文文本
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);
}
ret.ToString();
return ret.ToString();
}

/// <summary>
/// DEC   解密过程
/// </summary>
/// <param name="pToDecrypt">要解密的字符串</param>
/// <param name="sKey">密匙</param>
/// <returns></returns>
public static string Decrypt(string pToDecrypt, string sKey)
{
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);     //建立加密对象的密钥和偏移量，此值重要，不能修改
des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
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();     //建立StringBuild对象，CreateDecrypt使用的是流对象，必须把解密后的文本变成流对象

return System.Text.Encoding.Default.GetString(ms.ToArray());
}