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vault-door-3/VaultDoor3.java

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+import java.util.*;
+
+class VaultDoor3 {
+    public static void main(String args[]) {
+        VaultDoor3 vaultDoor = new VaultDoor3();
+        Scanner scanner = new Scanner(System.in);
+        System.out.print("Enter vault password: ");
+        String userInput = scanner.next();
+	String input = userInput.substring("picoCTF{".length(),userInput.length()-1);
+	if (vaultDoor.checkPassword(input)) {
+	    System.out.println("Access granted.");
+	} else {
+	    System.out.println("Access denied!");
+        }
+    }
+
+    // Our security monitoring team has noticed some intrusions on some of the
+    // less secure doors. Dr. Evil has asked me specifically to build a stronger
+    // vault door to protect his Doomsday plans. I just *know* this door will
+    // keep all of those nosy agents out of our business. Mwa ha!
+    //
+    // -Minion #2671
+    public boolean checkPassword(String password) {
+        if (password.length() != 32) {
+            return false;
+        }
+        char[] buffer = new char[32];
+        int i;
+        for (i=0; i<8; i++) {
+            buffer[i] = password.charAt(i);
+        }
+        for (; i<16; i++) {
+            buffer[i] = password.charAt(23-i);
+        }
+        for (; i<32; i+=2) {
+            buffer[i] = password.charAt(46-i);
+        }
+        for (i=31; i>=17; i-=2) {
+            buffer[i] = password.charAt(i);
+        }
+        String s = new String(buffer);
+        return s.equals("jU5t_a_sna_3lpm18gb41_u_4_mfr340");
+    }
+}