C# MD5 加密 string->string

private string MD5Encode(string text)
{
MD5 md5 = MD5.Create();
byte[] en = md5.ComputeHash(Encoding.Default.GetBytes(text));
StringBuilder sBuilder = new StringBuilder();
for (int i = 0; i < en.Length; i++)
{
sBuilder.Append(en[i].ToString("x"));
}
return sBuilder.ToString();
}