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_Crypt_EncryptFile issue

legend
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legend Universalist

legend

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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

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JohnOne Universalist

JohnOne

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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 Universalist

legend

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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 Universalist

legend

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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 Universalist

legend

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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.

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guinness Universalist

guinness

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

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Updated: 22/04/2018

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jchd Universalist

jchd

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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!

This wonderful site allows debugging and testing regular expressions (many flavors available). An absolute must have in your bookmarks.
Another excellent RegExp tutorial. Don't forget downloading your copy of up-to-date pcretest.exe and pcregrep.exe here
RegExp tutorial: enough to get started
PCRE v8.33 regexp documentation latest available release and currently implemented in AutoIt beta.

SQLitespeed is another feature-rich premier SQLite manager (includes import/export). Well worth a try.
SQLite Expert (freeware Personal Edition or payware Pro version) is a very useful SQLite database manager.
An excellent eBook covering almost every aspect of SQLite3: a must-read for anyone doing serious work.
SQL tutorial (covers "generic" SQL, but most of it applies to SQLite as well)
A work-in-progress SQLite3 tutorial. Don't miss other LxyzTHW pages!
SQLite official website with full documentation (may be newer than the SQLite library that comes standard with AutoIt)

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Melba23 Universalist

Melba23

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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 Universalist

JohnOne

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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

 

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

Monkey's are, like, natures humans.

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