Warsaw Crackme 1

Link: http://crackmes.cf/users/warsaw/java_crackme_1.1/
Answer: -975145735

Chucking this into MapleIL gives us

public final class Code extends java/io/PrintStream {
     // Code.main([Ljava/lang/String;)V
     public static final synchronized void main(java.lang.String[] arg0) {
            lvar0 = arg0
         C: // Exception handler: Block G [java.lang.Throwable]
            goto D
         D: // Exception handler: Block G [java.lang.Throwable]
            if (java.lang.Integer.decode(lvar0[0]).intValue() * -37 + 42 != 1720653869)
               goto E
         F: // Exception handler: Block G [java.lang.Throwable]
            lvar2 = "Correct!"
            goto H
         E: // Exception handler: Block G [java.lang.Throwable]
            lvar2 = "Incorrect"
         G: // Exception handler: Block G [java.lang.Throwable]
            lvar1 = catch()
            lvar2 = "Please enter a 32bit signed int"
            goto H
         H: // Exception handler: Block G [java.lang.Throwable]

Now it seems like obviously you just solve for the inverse of $f(x)=x*-37 + 42$ which is $f(x)^{-1}=\frac{x-42}{-37}$, but you will find that if you try to do this, you won’t be able to obtain the correct key. This is because the intended solution relies on the reverser to solve for integer overflowing. I’m way too lazy to do that so I just bruteforced the correct key through jshell.

jshell> for (int i = 0; i < Integer.MAX_VALUE; i++) { if ((i * 37) == (1720653869 - 42)) System.out.println(i); }

Therefore, the answer is -975145735.