using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;

public class EncryptMD5 
{
    /// <summary>
    /// 获取字符串MD5值
    /// </summary>
    /// <param name="sText"></param>
    /// <param name="encoding">编码方式 utf8</param>
    /// <param name="uppercase">true 大写；false 小写</param>
    /// <returns></returns>
    public static string Encrypt(string sText, Encoding encoding, bool uppercase = false)
    {
        byte[] buffer = encoding.GetBytes(sText);
        string s = Encrypt(buffer);
        if (!uppercase)
            s = s.ToLower();
        return s;
    }

    /// <summary>
    /// 获取字符串MD5值
    /// </summary>
    /// <param name="buffer"></param>
    /// <returns></returns>
    public static string Encrypt(byte[] buffer)
    {
        //使用MD5这个抽象类的Creat()方法创建一个虚拟的MD5类的对象。
        using (MD5 md5 = MD5.Create())
        {
            //使用MD5实例的ComputerHash()方法处理字节数组。
            byte[] bufferNew = md5.ComputeHash(buffer);

            string s = BitConverter.ToString(bufferNew, 0, bufferNew.Length);
            return s.Replace("-", "");
        }
    }

    /// <summary>
    /// 获取流MD5值
    /// </summary>
    /// <param name="inputStream"></param>
    /// <returns></returns>
    public static string Encrypt(Stream inputStream)
    {
        using (MD5 mi = MD5.Create())
        {
            //开始加密
            byte[] bufferNew = mi.ComputeHash(inputStream);
            string s = BitConverter.ToString(bufferNew, 0, bufferNew.Length);
            return s.Replace("-", "");
        }
    }

    /// <summary>
    /// 获取文件MD5值
    /// </summary>
    /// <param name="filename"></param>
    /// <returns></returns>
    public static string EncryptFile(string filename)
    {
        using (FileStream fs = new FileStream(filename, FileMode.Open))
        {
            return Encrypt(fs);
        }
    }
}