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Bringing TLS 1.3 to Haskell

Bringing TLS 1.3 to Haskell

Haskell TLS library version 1.4.1 or earlier support SSL 2.0, SSL 3.0, TLS 1.0, TLS 1.1 and TLS 1.2. Here is brief summary of their security:

  • SSL 2.0 is insecure and obsoleted by RFC 6176
  • SSL 3.0 is insecure and obsoleted by RFC 7568
  • TLS 1.0 is insecure due to lack of AEAD
  • TLS 1.1 is insecure due to lack of AEAD
  • TLS 1.2 is secure if it is used with proper parameters (using (EC)DHE and AEAD, disabling compression and renegotiation).

You may be surprised that both TLS 1.0 and TLS 1.1 are vulnerable. Actually, HTTP/2 requires TLS 1.2 with TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 or stronger. Also, major browsers are planning to disable TLS 1.0 and 1.1 in 2020.

To make your web sites secure, you should specify good parameters to TLS 1.2. Unless you are a security expert, it would be a tough job. Any other smart solutions? Yes, here is TLS 1.3.

Standardization of TLS 1.3 was finished in August 2018 and resulted in RFC 8446. It is secure by design. It allows only (EC)DHE for key exchange and only AEAD for traffic encryption. And it also removed compression and renegotiation.

Chrome and Firefox have supported TLS 1.3 in version 70 and version 63, respectively. To know support status of other browsers, please refer to Can I use.

So, it's high time to bring TLS 1.3 to the Haskell community. We proudly announce that we have released TLS library version 1.5.0 with TLS 1.3! To use TLS 1.3 in TLS library, you should specify TLS13 to supportedVersions. For more information, please see #167 and #282.

If you are using Warp TLS, you should obtain the newest Warp TLS and build it with TLS version 1.5.0. You can check if TLS 1.3 is used with Firefox or Chrome:

  • Firefox: click the lock beside the URL bar, ">" and "More Information".
  • Chrome: use the developer tool and click "Security" tab.

Since TLS 1.3 is a completely different protocol comparing to the older versions, I needed to write a lot of code. Olivier Chéron reviewed my code carefully and thoroughly. He also brought high-quality code to support missing features. My deep thank goes to him. I thank Vincent Hanquez and Viktor Dukhovni for enhancing crytonite and improving certification handling, respectively.

Enjoy TLS 1.3 in Haskell!