微软官方从.NET Framework 4之后不再支持System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(string password, string passwordFormat)方法。MD5加密需要自行实现。需要注意的是该方法加密结果是小写,而
HashPasswordForStoringInConfigFile加密结果是大写

public static string MD5Encrypt(string input)
{
	StringBuilder builder = new StringBuilder();
        using (MD5CryptoServiceProvider md5Crypto = new MD5CryptoServiceProvider())
        {
            byte[] data = md5Crypto.ComputeHash(Encoding.UTF8.GetBytes(input));
            for (int i = 0; i < data.Length; i++)
            {
                builder.Append(data[i].ToString("x2"));
            }
        }
        return builder.ToString();
}

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

namespace Utility.Security
{
    /// <summary>
    /// DES加密/解密类。
    /// </summary>
    public class DESEncrypt
    {
        /// <summary> 
        /// 加密数据 
        /// </summary> 
        public static string Encrypt(string Text, string sKey)
        {
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();
            byte[] inputByteArray;
            inputByteArray = Encoding.Default.GetBytes(Text);
            des.Key = ASCIIEncoding.ASCII.GetBytes(System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(sKey, "md5").Substring(0, 8));
            des.IV = ASCIIEncoding.ASCII.GetBytes(System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(sKey, "md5").Substring(0, 8));
            System.IO.MemoryStream ms = new System.IO.MemoryStream();
            CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write);
            cs.Write(inputByteArray, 0, inputByteArray.Length);
            cs.FlushFinalBlock();
            StringBuilder ret = new StringBuilder();
            foreach (byte b in ms.ToArray())
            {
                ret.AppendFormat("{0:X2}", b);
            }
            return ret.ToString();
        }

        /// <summary> 
        /// 解密数据 
        /// </summary> 
        public static string Decrypt(string Text, string sKey)
        {
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();
            int len;
            len = Text.Length / 2;
            byte[] inputByteArray = new byte[len];
            int x, i;
            for (x = 0; x < len; x++)
            {
                i = Convert.ToInt32(Text.Substring(x * 2, 2), 16);
                inputByteArray[x] = (byte)i;
            }
            des.Key = ASCIIEncoding.ASCII.GetBytes(System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(sKey, "md5").Substring(0, 8));
            des.IV = ASCIIEncoding.ASCII.GetBytes(System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(sKey, "md5").Substring(0, 8));
            System.IO.MemoryStream ms = new System.IO.MemoryStream();
            CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);
            cs.Write(inputByteArray, 0, inputByteArray.Length);
            cs.FlushFinalBlock();
            return Encoding.Default.GetString(ms.ToArray());
        }
    }
}

public sealed class AcrobatUtil
{
	public string ConvertToExecl(string inputFileName, string outputFileName)
	{
		//判断文件是否存在
		if (!File.Exists(inputFileName))
		{
			return "File Is Missing";
		}
		try
		{
			//判断是否已经安装Acrobat
			string acrobatPath = GetAppPath();
			if (acrobatPath == null)
			{
				return "Adobe Acrobat not installed.";
			}

			var aVDoc = new AcroAVDoc();
			aVDoc.Open(inputFileName, "");
			CAcroPDDoc PDDoc = (CAcroPDDoc)aVDoc.GetPDDoc();
			object jsObj = PDDoc.GetJSObject();
			var jsObjType = jsObj.GetType();
			//另存为
			jsObjType.InvokeMember(
							"saveAs",
							BindingFlags.InvokeMethod |
							BindingFlags.Public |
							BindingFlags.Instance,
							null, jsObj, new object[] { outputFileName, "com.adobe.acrobat.xlsx" });
/*
另存为更多格式
html htm      com.adobe.acrobat.html
jpeg jpg      com.adobe.acrobat.jpeg
docx          com.adobe.acrobat.docx
doc           com.adobe.acrobat.doc
png           com.adobe.acrobat.png
ps            com.adobe.acrobat.ps
rft           com.adobe.acrobat.rft
xlsx          com.adobe.acrobat.xlsx
xls           com.adobe.acrobat.spreadsheet
txt           com.adobe.acrobat.accesstext
tiff tif      com.adobe.acrobat.tiff
xml           com.adobe.acrobat.xml-1-00
*/
			//关闭文档
			aVDoc.Close(1);
		}
		catch (Exception ex)
		{
			return "Error:" + ex.Message;
		}
		return null;
	}
	
	//获取Acrobat安装路径
	private string GetAppPath()
	{
		string acrobatPath = null;
		using (RegistryKey acrobatRegistryKey = Registry.LocalMachine.OpenSubKey(@"SOFTWARE\Adobe\Adobe Acrobat"))
		{
			if (acrobatRegistryKey == null)
			{
				return acrobatPath;
			}
			string acrobatVersion = acrobatRegistryKey.GetValue("TrackName").ToString();
			using (RegistryKey acrobatInstallPathRegistryKey = acrobatRegistryKey.OpenSubKey(acrobatVersion + @"\InstallPath"))
			{
				if (acrobatInstallPathRegistryKey == null)
				{
					return acrobatPath;
				}
				acrobatPath = acrobatInstallPathRegistryKey.GetValue("").ToString() + @"\Acrobat.exe";
			}
		}
		return acrobatPath;
	}
}