Asp.Net(C#) MD5 加密

/// <summary>
/// MD5 字符串加密 
/// </summary>
/// <param name="str">需要加密的字符串</param>
/// <returns></returns>
public static string StringToMD5(string str)
{
    byte[] b = Encoding.Default.GetBytes(str);
    MD5 md5 = new MD5CryptoServiceProvider();
    byte[] result = md5.ComputeHash(b);
    StringBuilder sb = new StringBuilder();
    foreach (byte bt in result)
        sb.Append(bt.ToString("x2"));
    return sb.ToString();
}