[openssl-users] Checksum for openssl-1.0.2p download

[Michael Wojcik]

> From: openssl-users [mailto:openssl-users-bounces at openssl.org] On Behalf
> Of Matt Caswell
> Sent: Wednesday, September 12, 2018 14:29
>
> On 12/09/18 19:24, Chris Outwin wrote:
> > I’m an OpenSSL newbie and this is my first post. I’m using OpenSSL for
> receipt validation in an iOS application.
> >
> > Is there a list of checksums to verify openssl download versions?
>
> Next to each download on the website there are links for SHA256/PGP/SHA1
> checksums.
>
> https://www.openssl.org/source/

I'd strongly recommend verifying the PGP (OpenPGP, gpg) signature on the tarball. The signature files are right there alongside the tarballs.

If you're new to gpg (or whatever OpenPGP implementation of your choice), there's a bit of learning and setup to do: you'll need to fetch the appropriate key from a public keyserver or other trustworthy (-ish) source to fully verify the signature, and you'll probably want to mark the key as trusted so the output from gpg is clear.

But once you've done that, it's very easy to verify the signature, and to automate the process if you prefer. And the signatures add a bit of defense-in-depth because publishing a tampered-with tarball would require subverting the private key as well as to the OpenSSL web server.  (If you're just checking the SHA256 hash, an attacker could either get access to the OpenSSL web server, or force you to a counterfeit server, for example via DNS cache poisoning. And due to the systemic brokenness of the web PKI, it's pretty easy to fool a lot of people with a counterfeit server.)

So do the work now to set yourself up for verifying the signature, and inculcate a good habit.

--
Michael Wojcik
Distinguished Engineer, Micro Focus