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Is Nxt open or closed source?
Decompilation does take time and required several kinds of decompiler and manual editing to perform.
The source code is all made available for anyone who wants to make a copy. Or anyone who wants to permanently destroy Nxt. IMHO, security by obfuscation is really not a sound approach.
FrictionlessCoin only believes in "Security by Stupidity" - that is the only way to go!