Suggestion about reading encripted RAR archives

[Alextp]

Discussed at forum.wincmd.ru

What's the problem with usage of unrar.dll to read contents of encripted RAR archives? I mean archives with encripted header. Is it in Swiss laws?

The suggestions to workaround it:


1) Create ini key

AllowUnrarDecription=0

which is 0. When user sets it to 1, TC uses unrar.dll decription.


2) My suggestion: create separate unrar.dll without decription code.
The user can replace it with full version of unrar.dll to enable decription.

?

[roentgen]

Support.

Is it in Swiss laws?

I guess not. Looks like a left out feature.

[Flint]

What's the problem with usage of unrar.dll to read contents of encripted RAR archives? I mean archives with encripted header. Is it in Swiss laws?

http://ghisler.ch/board/viewtopic.php?p=50156#50156
http://ghisler.ch/board/viewtopic.php?p=109411#109411

[Alextp]

2Flint
I see. Now what about suggestions (you answered about 1st, let's see what Ghisler says).

[ghisler(Author)]

Sorry, I cannot offer TC for download if it contains any encryption or decryption function available to the user. Since unrar.dll already contains the function, and I cannot change it, I cannot use the trick as with unzip where someone else outside of Switzerland is offering an zip dll which supports encryption...

[Alextp]

I have a suggestion for this: can somebody patch unrar.dll (if Roshal will allow it!) so that is will miss exporting of encription function?
This is the function "RARSetPassword" or maybe "RARSetCallback".

That patched unrar.dll can be used in TC...

[DrShark]

2Alextp
"patch" is not right word, I think (UnRAR is opensource)...

By the way, I have a question to Christian:
if author of unrar.dll (E. Roshal) will make the subject without decryption part, will it possible to include it in TC installition instead of full version and allow to use decryption only if user replace it with full one?

[ghisler(Author)]

That's an interesting question - since it works with ZIP, it should work with RAR too...

[sas2000]

 
Last version of unrardll.exe seems to solve the problem including a second dll without decryption code.

http://www.rarlab.com/rar/UnRARDLL.exe

14 August 2007

Added \NoCrypt\unrar_nocrypt.dll without decryption code for those
applications where presence of encryption or decryption code is not
allowed because of legal restrictions.

---------------------------------------------------

This directory contains the version of unrar.dll built without
decryption code, authenticity verification code and RARSetPassword
function. It is intended for use in applictions where presence
of encryption or decryption code is not allowed because of legal
restrictions.

This DLL can be distinguished from usual unrar.dll by missing
RARSetPassword exported function. It sends UCM_NEEDPASSWORD notification,
but returns CRC error for encrypted files regardless of password
provided by application.

Bye.
 

[ghisler(Author)]

Yes indeed, the RAR author Eugene Roshal has contacted me personally about the DLL! I will certainly make use of it in the next release...

[Stitscher]

Great!

[Alextp]

Great!
Big thanks.

[sas2000]

 
Good news
 
I don't know how Tc installation/upgrade process works, but it may be a good idea that if user change current UnRar.dll attribute to read only, it should not be replaced with the new one (without decryption code) during upgrade process to Tc 7.02 or future versions, thanks.
 
 

[theosdikaios]

I will certainly make use of it in the next release...

Should it work with V7.02?
V7.02 package contains 'unrar_nocrypt.dll'. There is no hint in history.txt. It doesn't work like expected for me with exchanged unrar.dll which was downloaded from here
http://www.rarlab.com/rar/UnRARDLL.exe

[tbeu]

TC7.02 installation overwrites the unrar.dll (Vs. 3.70.100.211, 164 352 Byte) with unrar_nocrypt.dll (Vs. 3.70.100.211, 136 704 Byte).