One of the side-projects I did when I was fairly new to development -- but which forced me to make a big leap in my skills -- was to crack a database access too

One of the side-projects I did when I was fairly new to development -- but which forced me to make a big leap in my skills -- was to crack a database access tool I used, when they crippled the freeware version. The tool was written in Java, and I was coding in mostly Java, so I figured it'd be easy. That first version was indeed pretty simple to patch (decompile, find a class with a method that ran a bunch of license checks, and just replace that bit with "return true" then rebuild the JAR). Then they released another version with more serious obfuscation applied to it. I found myself digging through classfile specs, writing my own code to edit classes directly (where decompilers failed), etc.. As obfuscators evolved (and they upgraded), it got more interesting. I bought a license after a while (and I certainly didn't distribute my cracked versions; I liked the tool and wanted to support them), but I kept cracking new versions when they came out for a few years; it was entertaining & highly educational. I worked for a while on a standalone classfile editor, but eventually ran out of time for the hobby. But along the way I learned a good amount about Java bytecode, how the VM interpreted it (and how much flexibility there actually was involved). I learned about UTF-8 (and realized quickly that most text editors didn't seem to actually support it properly), put quite a lot of thought into security (trickier than I had thought) and how it relates to program flow (e.g., good design can easily mean more-easily-bypassed security). The real downside is that I couldn't brag about it to my colleagues, or online -- I didn't want to tangle with any potential legal issues, or reputation problems, especially at the start of my career. So I'd be walking around, buzzing with the new stuff I'd figured out (and new obstacles surmounted), but unable to say a word about it to anyone who would know what I was talking about. I considered contacting the developers of the tool directly, just to let them know this little contest was even happening and offer suggestions, but decided not to run even that risk.