AS2Secure is a PHP Lib to allow you to send and receive AS2 message from partners. Based on OpenSSL, documents are SIGNED and CRYPTED to build SMIME messages ready to be sent over HTTP connection.
An API and test suite, or possibly an application unto itself, to manage keys and allow mail user agents (such as pine or mutt) to use encryption and authentication systems (such as S/MIME) via the services of external encryption suites (such as OpenSSL)