_Crypt_EncryptFile how to encrypt files not completely?

[gerry1]

Hello!

You need to encrypt only the first 10 kilobytes

Here is the code for an example

 

$a_files = _FileListToArray(@ScriptDir)

For $i = 1 To $a_files[0]
    $rc  = _Crypt_EncryptFile($a_files[$i],$a_files[$i] & ".crypt", "APASSWORD", $CALG_AES_256)
    If $rc Then
        ConsoleWrite("File " & $a_files[$i] & " has been enencrypted to " & $a_files[$i] & ".crypt" & @CRLF)
    Else
        ConsoleWrite("Error: " & @error & @CRLF)
    EndIf
Next

 

[gerry1]

this code encrypts the files completely😐

 

[Nine]

Here.  This example show how to encrypt the first 100 bytes of a readable text file.

#include <Crypt.au3>

Local $hFileIn = FileOpen("Test.txt", $FO_BINARY)
Local $bContent = FileRead($hFileIn)
Local $bFirst = BinaryMid($bContent, 1, 100)

Local $bCrypt = _Crypt_EncryptData($bFirst, "APASSWORD", $CALG_AES_256)
ConsoleWrite(BinaryLen($bCrypt) & @CRLF) ; note the lenght, you will need it to decrypt

Local $hFileOut = FileOpen("Test2.txt", $FO_BINARY+$FO_OVERWRITE)
FileWrite($hFileOut, $bCrypt)
FileWrite($hFileOut, BinaryMid($bContent, 101))

FileClose($hFileIn)
FileClose($hFileOut)

 

Edited August 28, 2021 by Nine

[gerry1]

1 hour ago, Nine said:

Here.  This example show how to encrypt the first 100 bytes of a readable text file.

#include <Crypt.au3>

Local $hFileIn = FileOpen("Test.txt", $FO_BINARY)
Local $bContent = FileRead($hFileIn)
Local $bFirst = BinaryMid($bContent, 1, 100)

Local $bCrypt = _Crypt_EncryptData($bFirst, "APASSWORD", $CALG_AES_256)
ConsoleWrite(BinaryLen($bCrypt) & @CRLF) ; note the lenght, you will need it to decrypt

Local $hFileOut = FileOpen("Test2.txt", $FO_BINARY+$FO_OVERWRITE)
FileWrite($hFileOut, $bCrypt)
FileWrite($hFileOut, BinaryMid($bContent, 101))

FileClose($hFileIn)
FileClose($hFileOut)

 

this works, but I need to do it for all the files in the directory

[Nine]

2 hours ago, gerry1 said:

but I need to do it for all the files in the directory

Just loop thru it, as you did in your OP...I am sure you can do it. 

[gerry1]

41 minutes ago, Nine said:

Just loop thru it, as you did in your OP...I am sure you can do it. 

I did so, but the speed of code execution is important for me.. tell me how to speed up the script as much as possible 😊

[Nine]

Provide the final code, so we can have a look

[gerry1]

3 minutes ago, Nine said:

Provide the final code, so we can have a look

#include <Array.au3>
#include <File.au3>
#include <Crypt.au3>

$a_files = _FileListToArray(@ScriptDir)

For $i = 1 To $a_files[0]
Local $hFileIn = FileOpen($a_files[$i], $FO_BINARY)
Local $bContent = FileRead($hFileIn)
Local $bFirst = BinaryMid($bContent, 1, 100)

Local $bCrypt = _Crypt_EncryptData($bFirst, "APASSWORD", $CALG_AES_256)
ConsoleWrite(BinaryLen($bCrypt) & @CRLF) ; note the lenght, you will need it to decrypt

Local $hFileOut = FileOpen($a_files[$i] & ".backup", $FO_BINARY+$FO_OVERWRITE)
FileWrite($hFileOut, $bCrypt)
FileWrite($hFileOut, BinaryMid($bContent, 101))

FileClose($hFileIn)
FileClose($hFileOut)
Next

 

[Nine]

That seems alright.  But I wonder why you want to make backup using partly encrypted files ?

[gerry1]

2 minutes ago, Nine said:

That seems alright.  But I wonder why you want to make backup using partly encrypted files ?

I just wanted to figure out how to encrypt a file not completely. Since I didn't find anything like this on the internet.

I don't need to encrypt 10 kilobytes, I can also use a different size.

[jchd]

Will you need to decode such encrypted files as well?

[gerry1]

23 minutes ago, jchd said:

Will you need to decode such encrypted files as well?

yes

[Nine]

It is just about the same script but using DecryptData.  Like I wrote, as a comment in the script, the encrypted data is larger than the original data.  You need to use the appropriate size.  Another solution is to save the length as the first bytes of the backup file.

[JockoDundee]

5 hours ago, gerry1 said:

I just wanted to figure out how to encrypt a file not completely.

Did you think there was something more complicated than encrypting part of the file and then appending the rest of original file?