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| </div><div id='content' class='page-1'><div class='row'><div class='row-fluid'><div class='col-lg-3'><ul class='nav-sidebar'><li><a href='./'>Blog index</a></li><li class='active'><a href='#doc'>Fun with obfuscated Groovy</a></li></ul><br/><ul class='nav-sidebar'><li style='padding: 0.35em 0.625em; background-color: #eee'><span>Related posts</span></li><li><a href='./groovy-record-performance'>Groovy Record Performance</a></li><li><a href='./matrix-calculations-with-groovy-apache'>Matrix calculations with Groovy, Apache Commons Math, ojAlgo, Nd4j and EJML</a></li><li><a href='./testing-your-java-with-groovy'>Testing your Java with Groovy, Spock, JUnit5, Jacoco, Jqwik and Pitest</a></li><li><a href='./solving-simple-optimization-problems-with-groovy'>Solving simple optimization problems with Groovy using Commons Math, Hipparchus, OptaPlanner, and Timefold</a></li></ul></div><div class='col-lg-8 col-lg-pull-0'><a name='doc'></a><h1>Fun with obfuscated Groovy</h1><p><span>Author: <i>Paul King</i></span><br/><span>Published: 2022-12-08 12:40AM</span></p><hr/><div class="paragraph"> |
| <p>An interesting tweet appeared in my feed this morning:</p> |
| </div> |
| <div class="paragraph"> |
| <p><span class="image"><img src="img/bloch_obfuscated_java_tweet.png" alt="ObfuscatedJava@joshbloch" width="540"></span></p> |
| </div> |
| <div class="paragraph"> |
| <p>And of course it prints the same thing in Groovy:</p> |
| </div> |
| <div class="listingblock"> |
| <div class="content"> |
| <pre class="prettyprint highlight"><code data-lang="groovy">char p(int i) { |
| (char) (72.5 |
| + i * (17488.589319014318 |
| + i * (-54923.96120078333 |
| + i * (72666.96791801952 |
| + i * (-54398.97479321991 |
| + i * (25980.955221285272 |
| + i * (-8426.37914599868 |
| + i * (1921.5090334614745 |
| + i * (-313.59919165032926 |
| + i * (36.799215753141524 |
| + i * (-3.0787816564704586 |
| + i * (0.17913536718875267 |
| + i * (-0.0068850803421115925 |
| + i * (1.5709912194287188E-4 |
| + i * (-1.6109400409995646E-6 |
| ))))))))))))))) |
| } |
| |
| var i = 0 |
| while (p(i)) print p(i++)</code></pre> |
| </div> |
| </div> |
| <div class="paragraph"> |
| <p><span class="red">STOP</span> reading now and try it out for yourself … or browse the |
| <a href="https://community.oracle.com/tech/developers/discussion/1239419/java-code-obfuscation-contest">possible origin</a></p> |
| </div> |
| <div class="paragraph"> |
| <p><span class="red">SPOILER ALERT</span> okay, if you didn’t stop, I guess it’s still okay to scroll down to see what it prints out and how to create an obfuscated script yourself…</p> |
| </div> |
| <div class="paragraph"> |
| <p> <br> |
|  <br> |
|  <br> |
|  <br> |
|  <br> |
|  <br> |
|  <br> |
|  <br> |
|                 |
|                 |
|                ↓<br></p> |
| </div> |
| <div class="paragraph"> |
| <p> <br> |
|  <br> |
|  <br> |
|  <br> |
|  <br> |
|  <br> |
|  <br> |
|  <br> |
|                 |
|                 |
|                ↓<br></p> |
| </div> |
| <div class="paragraph"> |
| <p> <br> |
|  <br> |
|  <br> |
|  <br> |
|  <br> |
|  <br> |
|  <br> |
|  <br> |
|                 |
|                 |
|                ↓<br></p> |
| </div> |
| <div class="paragraph"> |
| <p> <br> |
|  <br> |
|  <br> |
|  <br> |
|  <br> |
|  <br> |
|  <br> |
|  <br></p> |
| </div> |
| <div class="paragraph"> |
| <p>Let’s Groovify the <a href="https://twitter.com/nikialeksey/status/1600598026678149120">reply</a> from |
| <a href="https://twitter.com/nikialeksey">Alexey Nikitin</a> which uses |
| <a href="https://commons.apache.org/proper/commons-math/">Apache Commons Math</a> to |
| replicate the problem:</p> |
| </div> |
| <div class="listingblock"> |
| <div class="content"> |
| <pre class="prettyprint highlight"><code data-lang="groovy">@Grab('org.apache.commons:commons-math3:3.6.1') |
| import org.apache.commons.math3.analysis.interpolation.NevilleInterpolator |
| |
| var text = 'Hello, world!\n' |
| var size = text.size() |
| var x = new double[size + 1] |
| var y = new double[size + 1] |
| for(i in 0..<size) { |
| x[i] = i |
| y[i] = (int) text[i] |
| } |
| x[size] = size |
| y[size] = 0 |
| |
| var lines = [] |
| var interpolator = new NevilleInterpolator() |
| var function = interpolator.interpolate(x, y) |
| var coeff = function.coefficients |
| lines << 'char p(int i) {' |
| lines << " (char) (${coeff[0]} + 0.5" |
| for(i in 1..<coeff.length) { |
| lines << ' + i * (' + coeff[i] |
| } |
| lines << ' ' + ')' * coeff.length |
| lines << '''} |
| var i = 0 |
| var out = '' |
| while(p(i)) out += p(i++) |
| out |
| ''' |
| var script = lines.join('\n') |
| println script |
| assert text == Eval.me(script)</code></pre> |
| </div> |
| </div> |
| <div class="paragraph"> |
| <p>This generates the script, prints it out, and then runs it to make sure it produces what we intended. It only differs from above in that instead of printing out each character, it builds up and returns a String so that we can assert our expectations. It was simpler than capturing stdout by other means.</p> |
| </div> |
| <div class="paragraph"> |
| <p>Enjoy!</p> |
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