Have you reasons to believe the existing x509 certificates handling code handles...

briansmith · on April 2, 2015

Some implementations--most unfortunately, Apple's--do not implement name constraints.

Speaking from personal experience, writing code to correctly validate x509 certificates isn't as hard as it looks.

brohee · on April 2, 2015

Then you're likely in the top 10 experts of the field ;)

The fact that OpenSSL did it wrong for 15 years doesn't bode well for the myriads of TLS implementations that are around.

My experience with the x509 part of SSL/TLS stacks is really not good when you start to use something else than OpenSSL/NSS (well PolarSSL is pretty good too). Quite often there is enough implemented to interoperate in the common use cases, but you're on your own if you need a complete standard support... Then it has been a while, maybe it's a lot better now.

brohee · on April 2, 2015

I wonder about the downvotes, with the long documented history of software failing to properly validate certificate chains (or worse, trees).

See for example http://blog.codekills.net/2012/04/08/adventures-in-x509-the-... about what really happens when one steps outside the well traveled path of certificate attributes...