tl;dr iOS9 applications only work with the newest SHA-256 certificates. If your iOS9 application or website is showing certificate errors and you’d like some help, contact email@example.com
iOS9 was recently released which brings a number of changes. In addition to the widely publicised changes about IPv6 (iOS9 prefers IPv6 and all applications in the App Store must function without issue on an IPv6 only network), Apple has forced obsolescence of older types of SSL certificate.
SSL certificates use hashing functions to provide security. The Secure Hash Algorithm 1 (SHA-1), was published by the NSA in 1995 as the standard for secure authentication. The first theoretical attacks were shown in 2005 leading to a recommendation in 2010 that we abandon SHA-1 and move to SHA-256. In 2014 Google put a sunset date for SHA-1 of December 2016 – if your website trusts an SHA-1 certificate past this date Chrome refuses to regard your site as secure.
With iOS9, Apple pulled the date at which everyday software stops working with SHA-1 forward. If your website or application is secured with a SHA-1 certificate, iOS9 gives warnings and errors. The fix is easy, we can provide or re-issue your existing certificate with an iOS9 compatible – and more importantly more secure – SHA-256 certificate.