The public key encryption standard 12 (PKCS# 12) specifies a portable format for storing and transmitting private keys, public keys and certificates of users or servers. This is a binary format, and these files are also called PFX files. Developers usually need to convert PFX files into some different formats, such as PEM or JKS, so that they can be used by independent Java clients or WebLogic Server using SSL communication. This paper introduces how to export private key, public key and certificate from PFX file and use them to create JKS or PEM file.

The above is a passage I copied. It doesn't seem to be a file that users need to open.