This was a really great time. It was my first talk for DCPHP and I had been hoping to speak about input validation for some time now. A while back I used PHP's filter functionality at a job that I had and it was able to stop errors that we were receiving from malicious users to crash the apache web server. Around that time, January 2014, I had seen a real life system come under attack by way of a denial of service. Input validation corrected the issue.
Afterwards I was able to find some great resources on the world wide web such as OWASP and CERT. In addition to this the National Vulnerability Database has been able to provide me and others with up to date information about security issues in computer software such as PHP.
The PHP Internals mailing list has also led me to a RFC by Yasuo Ohgaki at the php wiki web site. It is related to a new PHP filter module. I am interested in it as I have used the current filter module. You can find the RFC here.