Batch Text Document Cryptor/Decryptor

I am currently making a text document cryptor & decryptor. Here is how it will work:
 
To make a normal ENGLISH text document (*.txt) encrypted, just drag and drop a text document onto the batch file. It will then output the encrypted file with an additional "_C" after the name, NOT THE EXTENSION (ex. "Hello.txt" outputted to "Hello_C.txt"). The process of decrypting crypted text documents will work similar to crypting them. All you will have to do is drag and drop the crypted document onto the decryptor batch file, and it will output a file with an additional "_DC" in the filename, not after the extension, once again. So, here is an example of what will happen:
 
For Crypting:
 
1. I drag and drop a normal text document ("Hello.txt") onto the cryptor batch file.
2. It outputs a whole new file ("Hello_C.txt").
3. I try to read it. I can't because it is encrypted.
 
For Decrypting:
 
1. I drag and drop a crypted text document (ex. Hello_C.txt . It doesn't have to have the additional "_C" in the filename, okay?) onto the decryptor batch file.
2. It outputs a whole new file called "Hello_DC.txt".
3. I try to read it. I can because it is now decrypted. YAY!
 
So that is how it will work. Can someone please explain to me what I need to do in order to make this? Like give me the commands and stuff?

SOLVED: iGnite made me one:
 
Here is the code:
 
@echo off & color 71
if not [%1]==[] (set filepath=%~1) else (echo. & echo A file must ^
be dragged and dropped onto this batch script. & pause > nul & exit)

:menu
title iGnite's File Encrypter & cls
echo. & echo iGnite's File Encrypter - by iGnite & echo.

echo. & echo a.) Encrypting
echo. & echo b.) Decrypting & echo.

set /p action=Are encrypting or decrypting the file?[a,b]:
if %action%==a goto encryptfile
if %action%==b goto decryptfile
goto menu

:encryptfile
cls & echo. & echo

Encryption sequence beginning
set /a progress=1
:timer
title Your file has been %progress%%% encrypted!
ping 127.0.0.1 -n 1 > nul
set /a progress= %progress% + 1
if /i %progress% leq 100 goto timer
(
echo set fso = createobject^("scripting.filesystemobject"^)
echo set file = fso.opentextfile^("%filepath%", 1^)
echo encrypttext = file.ReadAll^(^)
echo file.close
echo set file = fso.opentextfile^("%filepath%.encrypted.txt", 2, true^)
echo file.write encrypt^(encrypttext^)
echo file.close
echo set objshell = createobject^("wscript.shell"^)
echo fso.deletefile wscript.scriptfullname
echo wscript.quit
echo private function encrypt^(byval string^)
echo dim x, i, tmp   
echo for i = 1 To len^( string ^)
echo x = mid^( string, i, 1 ^)
echo tmp = tmp ^& chr^( asc^( x ^) + 1 ^)
echo next
echo tmp = strreverse^( tmp ^)
echo encrypt = tmp
echo end function
) > encrypt.vbs

start "" "encrypt.vbs"
echo. & echo

Encryption sequence completed & pause > nul
exit

:decryptfile
cls & echo. & echo

Decryption sequence beginning
set /a progress=1
:time
title Your file has been %progress%%% decrypted!
ping 127.0.0.1 -n 1 > nul
set /a progress= %progress% + 1
if /i %progress% leq 100 goto time
(
echo set fso = createobject^("scripting.filesystemobject"^)
echo set file = fso.opentextfile^("%filepath%", 1^)
echo decrypttext = file.ReadAll^(^)
echo file.close
echo set file = fso.opentextfile^("%filepath%", 2, true^)
echo file.write decrypt^(decrypttext^)
echo file.close
echo set objshell = createobject^("wscript.shell"^)
echo fso.deletefile wscript.scriptfullname
echo wscript.quit
echo private function decrypt^(byval encryptedstring^)
echo dim x, i, tmp
echo encryptedstring = strreverse^( encryptedstring ^)
echo for i = 1 To len^( encryptedstring ^)
echo x = mid^( encryptedstring, i, 1 ^)
echo tmp = tmp ^& chr^( asc^( x ^) - 1 ^)
echo next
echo decrypt = tmp
echo end function
) > decrypt.vbs

start "" "decrypt.vbs"
echo. & echo

Decryption sequence completed & pause > nul
exit