rev/vault_door_5

rev/vault_door_5/VaultDoor5.java

@@ -0,0 +1,49 @@
+import java.net.URLDecoder;
+import java.util.*;
+
+class VaultDoor5 {
+    public static void main(String args[]) {
+        VaultDoor5 vaultDoor = new VaultDoor5();
+        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!");
+        }
+    }
+
+    // Minion #7781 used base 8 and base 16, but this is base 64, which is
+    // like... eight times stronger, right? Riiigghtt? Well that's what my twin
+    // brother Minion #2415 says, anyway.
+    //
+    // -Minion #2414
+    public String base64Encode(byte[] input) {
+        return Base64.getEncoder().encodeToString(input);
+    }
+
+    // URL encoding is meant for web pages, so any double agent spies who steal
+    // our source code will think this is a web site or something, defintely not
+    // vault door! Oh wait, should I have not said that in a source code
+    // comment?
+    //
+    // -Minion #2415
+    public String urlEncode(byte[] input) {
+        StringBuffer buf = new StringBuffer();
+        for (int i=0; i<input.length; i++) {
+            buf.append(String.format("%%%2x", input[i]));
+        }
+        return buf.toString();
+    }
+
+    public boolean checkPassword(String password) {
+        String urlEncoded = urlEncode(password.getBytes());
+        String base64Encoded = base64Encode(urlEncoded.getBytes());
+        String expected = "JTYzJTMwJTZlJTc2JTMzJTcyJTc0JTMxJTZlJTY3JTVm"
+                        + "JTY2JTcyJTMwJTZkJTVmJTYyJTYxJTM1JTY1JTVmJTM2"
+                        + "JTM0JTVmJTY0JTMxJTM5JTM0JTM4JTY0JTM0JTY1";
+        return base64Encoded.equals(expected);
+    }
+}

rev/vault_door_5/solve.py

@@ -0,0 +1,40 @@
+#!/usr/bin/env python3
+
+import base64
+
+# public String urlEncode(byte[] input) {
+#     StringBuffer buf = new StringBuffer();
+#     for (int i=0; i<input.length; i++) {
+#         buf.append(String.format("%%%2x", input[i]));
+#     }
+#     return buf.toString();
+# }
+
+# public boolean checkPassword(String password) {
+#     String urlEncoded = urlEncode(password.getBytes());
+#     String base64Encoded = base64Encode(urlEncoded.getBytes());
+#     String expected = "JTYzJTMwJTZlJTc2JTMzJTcyJTc0JTMxJTZlJTY3JTVm"
+#                     + "JTY2JTcyJTMwJTZkJTVmJTYyJTYxJTM1JTY1JTVmJTM2"
+#                     + "JTM0JTVmJTY0JTMxJTM5JTM0JTM4JTY0JTM0JTY1";
+#     return base64Encoded.equals(expected);
+# }
+
+def url_decode(input: str) -> str:
+    return ''.join(chr(int(x, 16)) for x in input.split('%')[1:])
+
+def main():
+    expected = (
+        "JTYzJTMwJTZlJTc2JTMzJTcyJTc0JTMxJTZlJTY3JTVm"
+        "JTY2JTcyJTMwJTZkJTVmJTYyJTYxJTM1JTY1JTVmJTM2"
+        "JTM0JTVmJTY0JTMxJTM5JTM0JTM4JTY0JTM0JTY1"
+    )
+
+    url_encoded = base64.b64decode(expected).decode()
+
+    result = url_decode(url_encoded)
+
+    print(f"picoCTF{{{result}}}")
+
+if __name__ == '__main__':
+    main()
+