Rustls

Prossimo Initiative
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Work Priorities

1. Support IP Address Certificates

There are some popular use cases where applications want TLS certificates for services that don’t have their own host name, relying on the IP address directly instead. I’ve heard from one customer that this is common in Kubernetes deployments. (Ticket)

2. Implement RFC 8446 Appendix C.4 in session cache

TLS clients should use session tickets at most once for resumption. Without this, TLS clients may be tracked across connections through reuse of session tickets. Requires changes of the internal APIs to the session caching infrastructure. (Ticket)

3. Improve Client Certificate Authentication Support

Rustls and webpki currently do not provide access to client information supplied as part of the certificate, and there’s no infrastructure to deal with revocation checks. (Ticket)

4. Add OS Trust Verifier Implementation

While we currently have a way to trust certificates stored in the platform trust store, platform trust stores can have other ways of restricting how/when roots that they expose are trusted. In order to rely on these (on Darwin and Windows) we should rely on the platform verifier directly. Given that platform verifiers may require blocking I/O, some API changes are required. (Ticket)

5. Reduce Memory Usage

Rustls currently keeps substantial handshake state around even after it is no longer needed for the exchange of application data, limiting scalability. (Ticket)

6. Add No-Allocation / Write-Through API

Would make handshakes faster and give the caller more control over allocations.

7. Support Encrypted Client Hello

Encrypted Client Hello is an upcoming standard from the TLS WG providing better production for some of the data sent by a client in the initial ClientHello message. (Ticket)

8. Support RFC 8879 Certificate Compression

Support for a TLS extension that substantially shrinks certificates (one of the largest parts of the TLS handshake), improving handshake latency by decreasing bandwidth used. (PR)

9. Add/extend support for TLS 1.3 Early Data

Early data allows clients to submit data before the TLS handshake is complete in some cases (idempotent requests, data where replay is not a risk), improving latency in the cases of, for example, HTTP requests by submitting the request in parallel with the TLS handshake.

10. Enforce Confidentiality / Integrity Limits

The QUIC use of TLS mandates limited usage of AEAD keys. While TLS 1.3 and 1.2 do not require this, the same kinds of issues can apply here, and we should consider implementing limits for TLS over TCP as well. (Ticket)

11. Verify DoS Resilience

Peers might send very large or very small messages, tying up resources in order to starve well-behaved connections.

12. Support no_std

Enables use of rustls in more memory-constrained environments. (Ticket)

13. FIPS Certification

Many organizations deploying TLS libraries required FIPS certification. RusTLS cannot be deployed at many organizations until it is FIPS certified.