循环使用加密算法,内存不断的增加,,,高手来看看

private const string sKey = "..............";
private const string sIV = "...";
private SymmetricAlgorithm mCSP = new TripleDESCryptoServiceProvider();
ICryptoTransform ct;
MemoryStream ms;
CryptoStream cs;
public Class3des()
{
mCSP.Key = Convert.FromBase64String(sKey);
mCSP.IV = Convert.FromBase64String(sIV);
mCSP.Mode = System.Security.Cryptography.CipherMode.ECB;
mCSP.Padding =                          System.Security.Cryptography.PaddingMode.PKCS7;
ct = mCSP.CreateEncryptor(mCSP.Key, mCSP.IV);
                            ms = new MemoryStream();
cs = new CryptoStream(ms, ct, CryptoStreamMode.Write); } 
public string EncryptString(string Value)
{ byte[] byt;
byt = Encoding.UTF8.GetBytes(Value);

cs.Write(byt, 0, byt.Length);
cs.FlushFinalBlock();
cs.Close();
return Convert.ToBase64String(ms.ToArray());
}