Auth systems/OAuth/Library

http://pear.php.net/package/HTTP_OAuth
 * New BSD License
 * last update 2011-07-16
 * 2200 lines of PHP (only 1050 excluding tests and examples)
 * Consumer depends on HTTP_Request2 but Provider appears to have no such dependency.
 * Can be bundled in a fake PEAR tree with include_path set appropriately
 * Minimal reference documentation.
 * Only supports one signature method, which is just a single hash_hmac call.
 * Fairly awkward request handling, but we can just rewrite it if this is all we need. Our own equivalent library written from scratch would be ~300 lines (with only the provider part).

PECL Extension
 * last updated 2012-10-01
 * "This pecl package is considered the de facto standard by Rasmus Lerdorf."
 * History of security-relevant bugs (dangling pointer, uninitialised stack pointer dereference, heap overflow in HTTP input handling)
 * 3800 lines of C
 * No package in Ubuntu
 * Minimal reference documentation. Has a provider tutorial.

http://code.google.com/p/oauth-php/
 * MIT License
 * Last update Nov 2010
 * No dependencies, easily bundled (but needs to be in include_path)
 * Needs add-on PHP file inside library tree to store via MW's DB layer, no simple callback interface provided
 * 6800 lines of PHP
 * Brief reference documentation in doc comments only. Has a provider tutorial.
 * Security of the SQL store was totally broken until March 2011

https://github.com/EHER/OAuth
 * Namespaces
 * Recent development
 * License?
 * 568 lines of PHP.
 * No need to bother integrating such a small library, just write it from scratch if this is all we need.

https://github.com/hwi/HWIOAuthBundle
 * 3600 lines of PHP
 * Includes UI
 * Supports two signature methods: HMAC (with hash_hmac) and RSA (with openssl_sign)