I have a site where I require to bar some people from accessing it, and creating new accounts due to rampant abuse.
IP banning, setting cookies to identify people proved to be useless since they use proxies and clear cookies.
I would like to save the "ban cookie" into flash, and have php respawn the http cookie if the flash cookie exists. Is there some sort of php/flash API that will allow me to write cookies into flash, and have php read them?
There are no PHP libraries for creating Flash files that support local shared objects (Flash cookies). The only PHP library for generating Flash files is Ming which does not support these.
To do this, you will need to manually create a Flash file that creates a local shared object and put that Flash file on your web page.
The easiest way to do this is to use the open source Flex SDK to compile an Actionscript file. You will need to learn a little bit of Actionscript to do this.
You can see the API for local shared objects here: http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/flash/net/SharedObject.html?filter_flex=4.1&filter_flashplayer=10.1&filter_air=2