Dotfuscator Professional obfuscation implements runtime decrypted String encryption. As mentioned before, any encryption (or specifically decryption) done at runtime is inherently insecure. That is, a smart hacker can eventually break it, but for Strings present in customer code, I found it worthwhile. Effectively, we apply a simple encryption algorithm (with a twist to thwart decompilers) to any strings in your application you desire. So you need to pay for the Professional version to get string encryption.