Encryped Core file in website
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I have a file called Core that is about 10 Mb. It is in the same directory that all the other main files of my website are in, such as Index.php. When I open it up, it looks encrypted. Can anyone tell me what the purpose of this file is?

My main concern is if the developer I worked with created this file for malicious purposes if he decides to use it. Is that possible?