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legend

_Crypt_EncryptFile issue

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legend

I've found a issue, regarding : _Crypt_EncryptFile

If you provide a wrong password, and even use @error, it will still try to decompile the file, the result will be a 1 kb file.

6ce00f2984.PNG

Edited by legend

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legend

Assume would probably have been the correct work.

I thank you :).

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JohnOne

I'm not certain that what you assume, is a bug. I don't see anything in the help file that says that is incorrect behaviour.

What error do you get? 

Whatever it is, you have the opportunity to delete any files.


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legend

There's no particular error in the syntax, but the behaviour is indeed a bug as I see it. Why would it be able to detect if the decryption was wrong, and then it will still attempt to decrypt it?.

See the first picture in the first post.

Sure I can delete the file that it generates, with the content: ÿÿÿÿ

Yet it's not a nice solution.

Edited by legend

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legend

I'm not getting any erros, 

It's the behaviour of _Crypt_EncryptFile, that it will generate a file with the content of "ÿÿÿÿ" 

When a wrong decryption password was used. that behaviour is just not logical, when it can detect it by @error.

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legend

The message box only shows if the decryption password was correct,

I have no clue how you aren't seeing that as a bug (the behaviour of creating a file, when a wrong decrypting password is provided).

 

But thank's for the luck.

Edited by legend

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guinness

This has been mentioned already. I think the conclusion was NO BUG!


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jchd

legend,

How on earth can you expect a cryptographic method to "see" that the recovered plaintext is wrong due to a wrong passphrase?

That would require one of two taboo things: either the passphrase is stored somewhere in the cyphertext (in which case decryption doesn't need you supply the passphrase, hence defeating the whole purpose of encryption) or the decrypt method has a way to behave as an oracle and recognize that the passphrase and the recovered plaintext is correct, which destroys plausible deniability and introduces a galaxy-large hole in the robustness of the cryptographic method employed.

Engage brain before posting and shouting bug!


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legend

Since it can detect if the decryption password was wrong, using: if @error, then it must be able to check whenever it's right or wrong i guess.

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legend

Since i'm clearly not able to explain the issue with words, I've made a video that shows the issue here:

http://youtu.be/osWWAud8MY4

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legend

I though you meant an error in the syntax checker.

fc0bbe187c.png

 

 

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Melba23

legend,

I have run the following snippet:

#include "Crypt.au3"

_Crypt_EncryptFile("test.txt", "encrypted.txt", "123", $CALG_AES_256)

; Use incorrect password
$bRet = _Crypt_DecryptFile("encrypted.txt", "wrongdecrypted.txt", "wrongpassword", $CALG_AES_256)
ConsoleWrite("Wrong Pword: " & $bRet & " - " & @error & @CRLF)

; Use correct password
$bRet = _Crypt_DecryptFile("encrypted.txt", "rightdecrypted.txt", "123", $CALG_AES_256)
ConsoleWrite("Right Pword: " & $bRet & " - " & @error & @CRLF)

; Use incorrect file
$bRet = _Crypt_DecryptFile("test.txt", "wrongfile.txt", "123", $CALG_AES_256)
ConsoleWrite("Wrong File:  " & $bRet & " - " & @error & @CRLF)

The results are as follows:

Wrong Pword: False - 420
Right Pword: True - 0
Wrong File:  False - 420

According to the Help file, the error says that the function "Failed to create key" and "Failed to decrypt final piece" - which seems perfectly logical to me and there is no differentiation between the 2 cases to help a would-be cracker determine the exact reason for the failure. In both error cases a small 4-byte file is created - which is the product of the internal Windows decryption code used by the Crypt library and nothing to do with AutoIt itself.

So what exactly are you complaining about?

M23


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JohnOne

I though you meant an error in the syntax checker.

So going back to what I said earlier and with the help of Melba23 posting the error, you might do something like...

If @error = 420 Then
    FileDelete("decrypted.txt")
    ;deal with whatever you need to
EndIf

 

  • Like 1

AutoIt Absolute Beginners    Require a serial    Pause Script    Video Tutorials by Morthawt   ipify 

Monkey's are, like, natures humans.

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