Detection of encrypted RAR5 archives

[clover21]

Hi, I am currently trying to use libarchive (13.4.3) to test if an archive is password protected.
I used "archive_entry_is_encrypted", which is working for zip and 7z archives. My problem is that it doesn't work for RAR5 archives (I didn't try older versions of RAR), the method returns false even if there is a password.

Am I missing something ? Is there a way to detect encrypted RAR5 archives ?

[mmatuska]

@antekone could you please give an answer to this question? Thanks.

[clover21]

My bad, I described the problem wrongly.
In fact libarchive cannot open my RAR5 archives at all (made with file-roler), encrypted or not.
I get a -30 return code when using "archive_read_open_filename" on them.
No wonder it cannot state about encryption then.

Is there a special way to open RAR5 files ? Is it not supposed to work ?

[mmatuska]

What version of libarchive are you using? 13.4.3 is unknown to me and 3.4.3 was released on May, 20th. If you have bsdtar installed you can check the version number with bsdtar --version

[antekone]

Sorry, from some reason I've missed this issue. Not sure why. @clover21 is it an option for you to share the RAR5 archives you're trying to open?

[clover21]

I don't have bsdtar.
I am currently using libarchive.so.13.2.2 but I reinstalled my laptop since the first message, so I was probably using libarchive.so.13.4.3 then, which may be an explanation of how I described the problem the first time (or maybe not since you say that version was not released, my memory is not the best).
I can try to get the last version.

I tried to attach some rar archives with this message but it says "We don't support that file type".

[clover21]

Well obviously the 3.2.2 was not yet managing RAR5 archives.
I think last time I built libarchive from git repo in my previous environment but since the laptop reinstall I went back to the version in Ubuntu repo.
I will try to get back the last version and confirm if the problem is as described first, a specific issue to detect if RAR5 archive is encrypted and not to open them in general.

[clover21]

OK, so I upgraded with build from current master.
It was like I said in the first message, archive_read_open_filename works on RAR5 archives but not archive_entry_is_encrypted, which returns false even when a password was set for the archive.
Is there a place where I can share an example of encrypted RAR5 archive like you suggested ?

[antekone]

Hi,

Current implementation of RAR5 unpacker in libarchive doesn't support encrypted archives.

I'm not an expert in libarchive's API, but I think it would be a nice addition to have some API to verify if a particular unpacker supports encryption or not. In current implementation, archive_entry_is_encrypted will always return false, since the unpacker reports 'unsupported':

static int rar5_has_encrypted_entries(struct archive_read *_a) {
    (void) _a;

    /* Unsupported for now. */
    return ARCHIVE_READ_FORMAT_ENCRYPTION_UNSUPPORTED;          
}  

I think if you're testing it on simple encrypted files, then there's no need to upload them anywhere.

If you only need to detect if RAR5 are encrypted or not, without actual decryption, I think it's possible to create small tool for it without much effort. Please give me a note if that's the case.

[clover21]

Thanks for the answer.
I ended up using another way to deal with encrypted archives.
I call 7z from my application and parse the output.
It's not as clean as using a library but it does the job for now.

[zyphs21]

Thanks for the answer.
I ended up using another way to deal with encrypted archives.
I call 7z from my application and parse the output.
It's not as clean as using a library but it does the job for now.

@clover21 Hello, I am facing the same problem: Can not detect whether the rar5 is encrypted or not ? Could you please tell me more about how you solve this problem?

[clover21]

Hi, like I said in my previous message, I execute 7z from my program (using exec in Golang) and parse the output of stdout to find relevant information. No clean, but it works somehow.