c# - Application copy protection using encrypted files -

i developing desktop app , want start selling @ point, start put license data (ex: start date, license duration, etc...) in encrypted file, during runtime of app decrypt file , license data check it.

the question is method enough copy protection ?

this question broad short answer is: depends on threat model. since application have decrypt file check contents, file have on client machine (along decryption key) if wants crack it, they'll have field day it. (they can attach debugger process , trace through code deals protection , either patch executable or figure out how generate valid license file. among other possible approaches didn't think of.)

if you're serious protecting software and think program popular many, many users try pirate it, buy professional solution - you'll professional advice on setting , protection have been tested in other products.

if that's expensive, re-evaluate whether need copy protection or not. home-brewed schemes can cracked in short order , they'll end annoying legitimate users , may turn out major headache you. you'll have support protection scheme , keep updated product evolves. keeping licenses backward compatible while being user-friendly , hard(-ish)-to-crack tricky.

a possible solution perform over-the-internet license check has own drawbacks , it's not cracker-proof either. if you're committed rolling own protection scheme, ready write lot of complicated code, in c or c++. (c# can decompiled free, open source tools.)

before that, ask yourself: wouldn't time better spent on new features instead of licensing code doesn't improve application itself?