Yes, we found this a while ago as well, and had to move extensions around. Cheers,
Andrei -----Original Message----- From: TLS [mailto:tls-boun...@ietf.org] On Behalf Of Wan-Teh Chang Sent: Thursday, March 24, 2016 12:04 AM To: Martin Thomson <martin.thom...@gmail.com> Cc: tls@ietf.org Subject: Re: [TLS] Empty extensions don't go last On Wed, Mar 23, 2016 at 10:30 PM, Martin Thomson <martin.thom...@gmail.com> wrote: > (This is probably already known to a bunch of people, but it's > probably a good idea to put out there.) > > When deploying EMS, we recently discovered, with the help of our > friends at Google (who discovered this long before that) a quirk in > some implementations. > > Short story: Don't place an empty extension at the end of your > ClientHello. You will find that a small number of servers choke. This interop problem surfaces when we added to Chrome the signed_certificate_timestamp extension for Certificate Transparency (RFC 6962): https://na01.safelinks.protection.outlook.com/?url=https%3a%2f%2fbugs.chromium.org%2fp%2fchromium%2fissues%2fdetail%3fid%3d353009%23c4&data=01%7c01%7cAndrei.Popov%40microsoft.com%7c916a8a6aa2eb4b8fd3e908d353b28e2d%7c72f988bf86f141af91ab2d7cd011db47%7c1&sdata=YUuVpA6X5QhQZGOS%2bHbs30ooKE%2bW9U0W4cr6tG%2bbKEo%3d https://na01.safelinks.protection.outlook.com/?url=https%3a%2f%2fbugs.chromium.org%2fp%2fchromium%2fissues%2fdetail%3fid%3d363583%23c13&data=01%7c01%7cAndrei.Popov%40microsoft.com%7c916a8a6aa2eb4b8fd3e908d353b28e2d%7c72f988bf86f141af91ab2d7cd011db47%7c1&sdata=ddplXkVwDs4SMUaRpcdc0TY%2fipYDB8rYwWeTAsvc0Kc%3d https://na01.safelinks.protection.outlook.com/?url=https%3a%2f%2fcodereview.chromium.org%2f240633006&data=01%7c01%7cAndrei.Popov%40microsoft.com%7c916a8a6aa2eb4b8fd3e908d353b28e2d%7c72f988bf86f141af91ab2d7cd011db47%7c1&sdata=5bQKBz4Y8R%2fmVKHLzpbnVBOj428W0T3regpgaBkl0MY%3d The change that David Benjamin made to ssl3_CalculatePaddingExtensionLength() in his patch probably should also be considered if the padding extension (RFC 7685) is placed at the end: https://na01.safelinks.protection.outlook.com/?url=https%3a%2f%2fcodereview.chromium.org%2f240633006%2fdiff%2f110001%2fnet%2fthird_party%2fnss%2fssl%2fssl3ext.c&data=01%7c01%7cAndrei.Popov%40microsoft.com%7c916a8a6aa2eb4b8fd3e908d353b28e2d%7c72f988bf86f141af91ab2d7cd011db47%7c1&sdata=jH5GKij0h%2boPSy4BaRvePsiN7zx2gycuSYraYDiTS4E%3d Wan-Teh Chang _______________________________________________ TLS mailing list TLS@ietf.org https://na01.safelinks.protection.outlook.com/?url=https%3a%2f%2fwww.ietf.org%2fmailman%2flistinfo%2ftls&data=01%7c01%7cAndrei.Popov%40microsoft.com%7c916a8a6aa2eb4b8fd3e908d353b28e2d%7c72f988bf86f141af91ab2d7cd011db47%7c1&sdata=gdOOA8X6H1QMVzL3JLh%2b%2f0YHesyIQKZjjhimdP3%2fYn0%3d _______________________________________________ TLS mailing list TLS@ietf.org https://www.ietf.org/mailman/listinfo/tls
