The Tor download page, Tor Project | Download should include the SHA256 hash values next to signatures.
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I don’t get the appeal of adding hash values additional to signatures. For advanced users that wants an additional security guarantee, using signature is better than a string of hash value, because they’re cryptographically linked to the Tor project team. For casual users, they just don’t verify and use whatever they downloaded.
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I disagree. Not everyone has the utilities (or wants the utilities) to check the sig using the asc file like I do. But I do agree that most will just use whatever they download.
I’m assuming the original writer is using Windows so right click on the file name and check the digital signature using properties. Windows uses it own trust chains to verify.
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This is purely my personal opinion, but the value of displaying hashes on the page is greatly overrated.
Signatures, yes, make sense, provided the key is downloaded through a secure channel.
But hashes present a completely unclear threat model. An adversary can hack TLS and replace the downloaded file, but they can’t change the hash displayed on the page. Where did it come from?
An adversary has root access to TorProject servers and can replace files with malicious ones, but can’t change the displayed hash on the page?
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OK I don’t get this.
Then this, to me, is saying that hashes are better. Now how does that adversary change the THE TOR PROJECT, INC. signature and the countersignature from Digicert in that replaced download? Or do you mean the GPG signature when you said hashes. In this scenario the adversary could also hack the asc file downloaded.
Agreed this adversary with root access could do anything.
That person is talking about the original post,i.e. SHA256 (or some other) hashes, not GPG or Windows binary signature.
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A hash is simplier when displayed on the site and requires less effort to verify the app, you also have a backup from sites like virustotal to confirm the sha256 hash.
Since the hash is a simple character based value there should be no reason not to display it in the download along with the Signature and allow the users to choose.
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A hash on website is also less capable of delivering desired security guarantee. Unless Tor Project website is redirecting users to mirror sites to download files (which it didn’t), the correctness of hashes and the integrity of the downloaded files relies on the same safety measure.
For the sake of clarity, let’s assume you went to Tor Project’s website to download the Browser…
- If you’re served the correct hash, your TLS connection with Tor Project’s server is intact, and Tor Project’s server isn’t intruded by attackers, so you most likely already have downloaded genuine, unmodified Tor Browser.
- If you’re served a modified Tor Browser, laced with malware, either Tor Project’s web servers have already been breached, or you’re suffering from a targetted MITM attack and the attackers somehow got a valid TLS certificate to impersonate Tor Project webservers. Either way, it’s unlikely you would be served a correct hash after downloading the mal-tor browser (it would be a rookie mistate NOT to do so, since attacker already has the capability to replace the correct hash either way).
But on Windows, you also need specialized utility to obtain the hash of a file.
Unless you use the PowerShell cmdlet Get-FileHash, but come on, how many Windows users even know PowerShell?
Not that specialized. 7-Zip portable is all you need but you don’t even need that. If you right click the file and go into properties you can check the digital signature of the file. I did an experiment. I changed a lowercase letter in the executable to an uppercase ( a 1 bit change) and it did not verify using the right click method.
Next to none. I know it’s there but never used it. Weird language. Wonder who invented it.
Most Windows user never use the command line or even know it exists.
Still more software to be installed. Also given that Windows 11 can now compress to 7z and tar and open rar archives, I’d expect less people feeling the need to install 7-Zip on their computers, and use of 7-Zip is limited to calculate file hashes for casual users that don’t need to deal with all kinds of archive files.
signatures. This is the second time I remind you that we’re talking about adding hash value of files to the website here, not digital signatures, neither PGP signatures nor Windows binary signatures.
Sure it’s probably good to add a guide about how to use Windows binary signatures to verify Tor Browsers, but please open another thread to discuss that matter. This is off topic for this thread.