What is a Zend Engine (ZE) Extension?

A ZE extension is a software component that extends the functionality of the PHP core. Examples of popular extensions are PHP accelerators and loaders for encoded scripts.

Why are some extensions "trusted" but not all?

Engine Extensions can control the behaviour of PHP at runtime and are therefore very powerful. There are some useful closed source and open source extensions for PHP, but extensions may also be created with malicious intent to subvert the behaviour of PHP. Some developers of PHP scripts may not wish their code to run in an environment where unknown, and therefore untrusted, extensions are running, and the ionCube Encoder provides an option for developers to produce scripts that will run only when known extensions are installed.

How can I use ionCube encoded files in an untrusted environment?

For maximum compatibility, the majority of encoded scripts from developers will run with any extension installed, known or unknown, closed source or open source. However if you reached here because a script reported that an untrusted extension was installed, you should contact the developer of the PHP script. Whilst a system may be using an extension that cannot be verified to be genuine, in most cases an extension will be a legitimate and unmodified version of a component such as EAccelerator or APC, particularly if running on a hosting provider, and activating untrusted extension protection is not necessary.