OpenSSL VS ring

Today, April 7th, 2024, marks the 10-year anniversary since CVE-2014-0160 was published. This security vulnerability known as "Heartbleed" was a flaw in the OpenSSL cryptography software, the most popular option to implement Transport Layer Security (TLS). In more layman's terms, if you type https:// in your browser address bar, chances are high that you are interacting with OpenSSL.

At this point I pretty much understand the entire process on how the xz backdoor came to be: its execution stages, extraction from binary "test" files etc. But one thing puzzles me: how can the ifunc mechanism be used to replace something like RSA_public_decrypt? Granted this probably stems from my lack of understanding of ifunc, but I was under the impression that in order for the ifunc mechanism to work in your code, you have to explicitly mark specific function with multiple implementations with __attribute__ ((ifunc ("the_resolver_function"))). Looking at the source code of the RSA function in question, ifunc attribute isn't present:

https://github.com/openssl/openssl/blob/master/crypto/rsa/rsa_crpt.c#L51

So how does the backdoor actually replace the call? Does this means that the ifunc mechanism can be used to override pretty much anything on the system?

OpenSSL and Go crypt/tls has no support yet, so none of the webservers that depend on them support it. Apache, Nginx, and Caddy, they all need upstream ECH support first.

- https://github.com/openssl/openssl/issues/7482

- https://github.com/openssl/openssl/pull/22938

- https://github.com/golang/go/issues/63369

If I'm understanding the draft correctly, I think the webserver you're hosting your sites on would need it implemented as it requires private keys and ECH configuration. In the example of nginx since it uses openssl, openssl would need to implement it. I found an issue on their Github but it's still open: https://github.com/openssl/openssl/issues/7482

I confirmed that the systm was on 1.1.1f with openssl version command. Hmm...... I check the openssl version in the repo with apt list... LOL package names wernt helpful. finally went to the repo pages and found that its still on 1.1.1f, https://launchpad.net/ubuntu/+source/openssl. Meenwhile I looked up the version history on https://www.openssl.org/ and saw that 1.1.1v was released at the beginning of this month... ok. I can understand it it was out less then 30 days. I looked up when f came out, end of MARCH 2020. NEARLY 3-1/2 YEARS

Again, this is just a temporary situation, and a matter of burning down a list of small tasks. Not that the OpenSSL license issue is a big deal for most anyway. Feel free to help; see this issue filed by Josh Triplett: https://github.com/briansmith/ring/issues/1318#issuecomment-...

Note also that rustls depends on ring, which has architecture-dependent code in it that is not as widely compatible as eg. OpenSSL/GnuTLS/Mbed-TLS. For example, MIPS is not supported by ring.

The AWS Rust library we were using as a dependency depended on a cryptography library called ring. This library leverages C and assembly code to implement its cryptographic primitives. Unfortunately, cross compiling when C is involved can add complexity to the build process. While it might've been possible to overcome these issues I decided that it wasn't worth digging into more.

That'd be great. Thanks Brian. Re: making ring portable to all platforms: IBM have been graciously maintaining a up to date patchset for Ring for years now and there's an outstanding PR here you may not have seen since they filed it in 2020... https://github.com/briansmith/ring/pull/1057

Beyond the simple matter of Rust being much newer than OpenSSL, one concern for some cryptographic primitives is the timing side-channel.

https://en.wikipedia.org/wiki/Timing_attack

In high level languages like Rust, the compiler does not prioritise trying to emit machine code which executes in constant time for all inputs. OpenSSL has implementations for some primitives which are known to be constant time, which can be important.

One option if you're working with Rust anyway would be use something like Ring:

https://github.com/briansmith/ring

Ring's primitives are just taken from BoringSSL which is Google's fork of OpenSSL, they're a mix of C and assembly language, it's possible (though fraught) to write some constant time algorithms in C if you know which compiler will be used, and of course it's possible (if you read the performance manuals carefully) to write constant time assembly in many cases.

In the C / assembly language code of course you do not have any safety benefits.

It can certainly make sense to do this very tricky primitive stuff in dangerous C or assembly, but then write all the higher level stuff in Rust, and that's the sort of thing Ring is intended for. BoringSSL for example includes code to do X.509 parsing and signature validation in C, but those things aren't sensitive, a timing attack on my X.509 parsing tells you nothing of value, and it's complicated to do correctly so Rust could make sense.

machine learning, neural networks, image processing, cryptography (though it is getting better), font shaping/rendering (though it is getting better), CPU/software rendering (though it is getting better)