It's time for TLS 1.0 and 1.1 to die (die, die)

As TLS 1.3 inches towards publication into the Internet Engineering Task Force's RFC series, it's a surprise to realise that there are still lingering instances of TLS 1.0 and TLS 1.1.

The now-ancient versions of Transport Layer Security (dating from 1999 and 2006 respectively) are nearly gone, but stubborn enough that Dell EMC's Kathleen Moriarty and Trinity College Dublin's Stephen Farrell want it formally deprecated.

This Internet-Draft (complete with “die die die” in the URL) argues that deprecation time isn't in the future, it's now, partly because developers in recalcitrant organisations or lagging projects probably need something to convince The Boss™ it's time to move.

The last nail in the coffin would be, formally and finally, to ban application fallback to the hopelessly insecure TLS 1.0 and 1.1 standards.

Deprecation also removes any excuse for a project to demand support for all four TLS variants (up to TLS 1.3), simplifying developers' lives and reducing the risk of implementation errors.

Since the PCI Council's deprecation deadline of June 30, 2018, is fast approaching, the Draft notes that deprecation now would be timely.

The document also notes that apart from websites, organisations like 3GPP 5G, CloudFlare, Amazon and GitHub have either completed their deprecation or will finish the job by July.

The requirement itself is simple enough: “Pragmatically, clients MUST NOT send a ClientHello with ClientHello.client_version set to {03,01}. Similarly, servers MUST NOT send a ServerHello with ServerHello.server_version set to {03,01}. Any party receiving a Hello message with the protocol version set to {03,01} MUST respond with a 'protocol_version' alert message and close the connection.”

The publication of TLS 1.3 into the RFC stream is imminent – it's reached the last stage of the pre-publication process, author's final review. When it's published, it will carry the designation RFC 8446.

Props to Michal Špaček for noticing that the RFC's publication number carries on something of a tradition for TLS standards. ®