The way encryption works is by translating the data into what appears to be random bytes of data based on the translations within your certificate. Of course there are other forms of encryption and methods to encrypt information, but here we are speaking strictly on behalf of how the industry standard of digital encryption functions. While the data is in an encrypted state, you don't really know what you're looking at until you find a header, if the header is stored on the same medium you have access to (some people store their headers or build them each time they want to decrypt their data depending on the sensitivity of the information), etc. However, this data requires a certificate that contains the data needed to "translate" the data while it is in an encrypted state. Once the data enters your memory and read, it is essentially no longer encrypted as the data is being translated from an encrypted state to be decoded and read within the memory and processed. With the exception of instruction code encryption which I believe was created by Intel (which only protects the data while it is in transit to the CPU from your RAM and so forth), there is one flaw in encryption, once the data is translated, it is essentially no longer encrypted. This is a fundamental flaw in every implementation of industry standard encryption because no matter what happens, it does enter a decrypted state at some point in the information flow. However, there are ways to manipulate the information that is in the memory and keep Blizzard from reading it, which is already done with how Tripwire is implemented and that's where I'll leave it.
A great example is when you encrypt your data and get yourself infected in any way that allows access to your data, such as backdoored or shelled (the most dangerous forms of having someone or something possess remote access over your machine because someone can leverage legitimate dependencies in your system to exfiltrate the information) even with FDE (Full disk encryption), once it is read and decrypted, anyone can exfiltrate the information, but there are also ways you can keep that from happening as well, but most individuals don't have any clue how deep that rabbit hole goes.
This is just a brief summary, as there are more in depth explanations I can give you, but you just need a general understanding of how the information is encrypted, stored and decrypted. If you want more information, I suggest you purchase a book or start reading on Wikipedia or some journals published by well reputed colleges and individuals within the industry.