GnuPG allows to encrypt and sign the data and communication, features a versatile key management system as well as access modules for all kinds of public key directories.
PHP: Hypertext Preprocessor is a server-side scripting language designed for Web development, but also used as a general-purpose programming language. PHP code may be embedded into HTML code, or it can be used in combination with various web template systems, web content management systems, and web frameworks.