其他常用方法详见：https://www.cnblogs.com/zhuanjiao/p/12060937.html
/// <summary>
/// 32位MD5加密（小写）
/// </summary>
/// <param name="input">输入字段</param>
/// <returns></returns>
public string Encrypt(string str)
{
MD5CryptoServiceProvider md5Hasher = new MD5CryptoServiceProvider();
byte[] data = md5Hasher.ComputeHash(Encoding.Default.GetBytes(str));
StringBuilder sBuilder = new StringBuilder();
for (int i = 0; i < data.Length; i++)
{
sBuilder.Append(data[i].ToString("x2"));//转化为小写的16进制
}
return sBuilder.ToString();
}