An update on SSH protocol 1

Hi, At this stage, we're most of the way towards fully deprecating SSH protocol 1 - this outlines our plans to complete this task. We've had this old protocol in various stages of deprecation for almost 10 years and it has been compile-time disabled for about a year. Downstream vendors, to their credit, have included this change in recent OS releases by shipping OpenSSH packages that disable protocol 1 by default and/or offering separate, non-default packages to enable it. This seems to have proceeded far more smootly than even my most optimisitic hopes, so this gives us greater confidence that we can complete the removal of protocol 1 soon. We want to do this partly to hasten the demise of this cryptographic trainwreck, but also because doing so removes a lot of legacy code from OpenSSH that inflates our attack surface. Having it gone will make our jobs quite a bit easier as we maintain and refactor. So here are our plans. Dates are estimates only. * June 2016 Release OpenSSH 7.3. SSH protocol 1 is unchanged. We start mention these plans in the release notes to give them wider publicity. * August 2016 Release OpenSSH 7.4. Server-side support for SSHv1 is removed from our codebase. Client support remains disabled by default. * June 2017 OpenSSH removes all SSH protocol 1 support. -- So this is just over a year of notice ahead of final deprecation. After we release OpenSSH without SSHv1 support, users who absolutely need it would have to use a prior version of OpenSSH or some other implementation. We recognise that this may leave some users without a supported client for their protocol v1 hosts, but we feel that >10 years of transition is time enough. Feedback is welcome. Cheers, Damien Miller (on behalf of the team)