There are programs that are called obfuscators that employ various techniques to make the process of decompiling an application less easy. Here is is a pdf which wraps up pretty good what Obfuscation is all about:
Introduction To Program Obfuscation[
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One method is encryption and this is what most probably happend to these strings. This technique comes at a cost as the strings will have to be decrypted when they're being accessed during the programs runtime. Good obfuscators allow you to configure for performance optimization in doing the decryption at program start up. This is of course a trade off security wise as the program's memory can now be analyzed.
Another thing that obfuscators do is to rename non public members that make it even harder to understand the program. Most programmers use method names and field names that carry a certain semantic. A method called Write() sounds like it will produce some output. If it were called XD5§GL() all that is left to do is analyze the whole method.
Obfuscation is no means to stop any determined individual from finding out what your program does, but it can slow them down considerably.
I hope this solution was helpful to you.
Cheers!