In June 2015, we introduced s2n, an open-source implementation of the TLS encryption protocol, making the source code publicly available under the terms of the Apache Software License 2.0 from the s2n GitHub repository. One of the key benefits to s2n is far less code surface, with approximately 6,000 lines of code (compared to OpenSSL’s approximately 500,000 lines). In less than two years, we’ve seen significant enhancements to s2n, with more than 1,000 code commits, plus the addition of fuzz testing and a static analysis tool, tis-interpreter.

Today, we’ve achieved another important milestone for securing customer data: we have replaced OpenSSL with s2n for all internal and external SSL traffic in Amazon Simple Storage Service (Amazon S3) commercial regions. This was implemented with minimal impact to customers, and multiple means of error checking were used to ensure a smooth transition, including client integration tests, catching potential interoperability conflicts, and identifying memory leaks through fuzz testing.

It was only last week that AWS CEO Andy Jassy reiterated something that’s been a continual theme for us here at AWS: “There’s so much security built into cloud computing platforms today, for us, it’s our No. 1 priority—it’s not even close, relative to anything else.” Yes, security remains our top priority, and our commitment to making formal verification of automated reasoning more efficient exemplifies the way we think about our tools and services. Making encryption more developer friendly is critical to what can be a complicated architectural universe. To help make security more robust and precise, we put mechanisms in place to verify every change, including negative test cases that “verify the verifier” by deliberately introducing an error into a test-only build and confirming that the tools reject it.

If you are interested in using or contributing to s2n, the source code, documentation, commits, and enhancements are all publicly available under the terms of the Apache Software License 2.0 from the s2n GitHub repository.

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