对称加密速度比不对称加密要快

///   <summary>
///   获得密钥
///   </summary>
///   <returns> 密钥 </returns>
private   byte[]   GetLegalKey()
{
string   sTemp   =   Key;
mobjCryptoService.GenerateKey();
byte[]   bytTemp   =   mobjCryptoService.Key;
int   KeyLength   =   bytTemp.Length;
if   (sTemp.Length   >   KeyLength)
sTemp   =   sTemp.Substring(0,   KeyLength);
else   if   (sTemp.Length   <   KeyLength)
sTemp   =   sTemp.PadRight(KeyLength,   '   ');
return   ASCIIEncoding.ASCII.GetBytes(sTemp);
}
///   <summary>
///   获得初始向量IV
///   </summary>
///   <returns> 初试向量IV </returns>
private   byte[]   GetLegalIV()
{
string   sTemp   =   "E4ghj*Ghg7!rNIfb&95GUY86GfghUb#er57HBh(u%g6HJ($jhWk7&!hg4ui%$hjk ";
mobjCryptoService.GenerateIV();
byte[]   bytTemp   =   mobjCryptoService.IV;
int   IVLength   =   bytTemp.Length;
if   (sTemp.Length   >   IVLength)
sTemp   =   sTemp.Substring(0,   IVLength);
else   if   (sTemp.Length   <   IVLength)
sTemp   =   sTemp.PadRight(IVLength,   '   ');
return   ASCIIEncoding.ASCII.GetBytes(sTemp);
}
///   <summary>
///   加密方法
///   </summary>
///   <param   name= "Source "> 待加密的串 </param>
///   <returns> 经过加密的串 </returns>
public   string   Encrypto(string   Source)
{
byte[]   bytIn   =   UTF8Encoding.UTF8.GetBytes(Source);
MemoryStream   ms   =   new   MemoryStream();
mobjCryptoService.Key   =   GetLegalKey();
mobjCryptoService.IV   =   GetLegalIV();
ICryptoTransform   encrypto   =   mobjCryptoService.CreateEncryptor();
CryptoStream   cs   =   new   CryptoStream(ms,   encrypto,   CryptoStreamMode.Write);
cs.Write(bytIn,   0,   bytIn.Length);
cs.FlushFinalBlock();
ms.Close();
byte[]   bytOut   =   ms.ToArray();
return   Convert.ToBase64String(bytOut);
}
///   <summary>
///   解密方法
///   </summary>
///   <param   name= "Source "> 待解密的串 </param>
///   <returns> 经过解密的串 </returns>
public   string   Decrypto(string   Source)
{
byte[]   bytIn   =   Convert.FromBase64String(Source);
MemoryStream   ms   =   new   MemoryStream(bytIn,   0,   bytIn.Length);
mobjCryptoService.Key   =   GetLegalKey();
mobjCryptoService.IV   =   GetLegalIV();
ICryptoTransform   encrypto   =   mobjCryptoService.CreateDecryptor();
CryptoStream   cs   =   new   CryptoStream(ms,   encrypto,   CryptoStreamMode.Read);
StreamReader   sr   =   new   StreamReader(cs);
return   sr.ReadToEnd();
}
}
}