Comparing OpenSSL with BoringSSL

BoringSSL is another fork of OpenSSL that was made public in 2014. BoringSSL was made for the needs of the Google corporation. For years, Google maintained its own patches for OpenSSL for use in various Google products, such as Chrome, Android, and the server’s infrastructure. Finally, they decided to fork OpenSSL and maintain their fork as a separate library.

Like LibreSSL, in BoringSSL, Google removed a lot of the original OpenSSL code, which was responsible for supporting old and unpopular algorithms and features. Google also added some functionality that does not exist in OpenSSL. For example, the CRYPTO_BUFFER functionality allows you to deduplicate X.509 certificates in memory, thus reducing memory usage. It also allows you to remove OpenSSL’s X.509 and ASN.1 code from the application if OpenSSL is linked statically to the application. The X.509 code is a sizeable part of OpenSSL.

Unlike LibreSSL, BoringSSL does not aim for API compatibility with OpenSSL, or even with former versions of BoringSSL. Google wants to change the library API at will. It makes sense because Google controls both BoringSSL and the major software projects that use the library, which makes it possible to synchronize the API changes in BoringSSL and those projects. If the API is not kept stable, it is possible to free up development resources that would otherwise be spent on maintaining the old APIs.

But this also means that if someone outside Google wants to use BoringSSL, they should be ready for breaking changes in the library API, at the least suitable times. This is very inconvenient for developers who use the library. Google understands this and states that although BoringSSL is an open source project, it is not for general use.

My opinion is that BoringSSL was made open source mostly for third-party contributors to Google projects, such as Chrome and Android.

I do not recommend using BoringSSL in your applications due to its API instability. Furthermore, OpenSSL has more features, better documentation, and a much larger community.

With that, we have reviewed several competitors of OpenSSL. You should now understand the main differences between the popular TLS libraries and which library should be used in which case.

Let’s proceed to the summary.