AES-256

[orb_505]

Hi all,

I'm writing a program which will copy a file from a HDD to a USB pen. I want the file to be encrypted on the USB pen using AES-256. Does anyone know if this can be done and if so a code example?

Many thanks

Mark

[cas]

Yes, it can be done. Just use PB help file and go through these commands:

OpenFileRequester()/SaveFileRequester()
ReadFile()
AllocateMemory()
ReadData()
AESEncoder()
CreateFile()
CloseFile()

[orb_505]

Hi Cas,

I saw the AESEncoder command but it gave the impression it was for strings. Either way I'm not creating the file but copying it using CopyFile(), the file itself isn't created by my program, a third party creates it, I just want it copying to a USB pen but then for the security of postal transportation encoding it via AES.

I was hoping for a command which you could just throw it the filename and it'll encrypt it for you

Mark

[netmaestro]

The approach depends on the file size. How large is it?

[orb_505]

The size can vary but anything up to a gig really.

[Little John]

Encryption is not only for strings. Actually, AES encrypted data can contain zeros somewhere in the middle, which is not possible with PB strings.

Here is a basic algorithm for copying a file of arbitrary size (as long as there is enough free space on the target drive):

Code: Select all

; tested with PB 4.50

EnableExplicit

#MaxChunk = 4096

Procedure.i Copy (infile$, outfile$)
   Protected ifn, ofn, bytes
   Protected *buffer

   ifn = ReadFile(#PB_Any, infile$)
   If ifn = 0
      ProcedureReturn #False          ; error
   EndIf

   ofn = CreateFile(#PB_Any, outfile$)
   If ofn = 0
      CloseFile(ifn)
      ProcedureReturn #False          ; error
   EndIf

   *buffer= AllocateMemory(#MaxChunk)
   Repeat
      bytes = ReadData(ifn, *buffer, #MaxChunk)
      ; +----------------------------------------------+
      ; | Do encryption or other funny stuff here with |
      ; | the memory block to which *buffer points.    |
      ; +----------------------------------------------+
      WriteData(ofn, *buffer, bytes)
   Until bytes < #MaxChunk
   FreeMemory(*buffer)
   CloseFile(ofn)
   CloseFile(ifn)
   
   ProcedureReturn #True              ; success
EndProcedure

Define infile$, outfile$

infile$ = "source.dat"
outfile$ = "target.dat"
If Copy(infile$, outfile$)
   Debug "OK"
Else
   Debug "Error"
EndIf

Regards, Little John

[netmaestro]

I made you an answer:

http://www.purebasic.fr/english/viewtop ... 12&t=43118

[orb_505]

Thats great! Many thanks! I'm just working on shoe-horning it into my program.

Cheers!

Mark