Init. Commit

finals/nullroute-kem-crypto-easy/solve/solve.py

@@ -0,0 +1,31 @@
+#!/usr/bin/env python3
+import importlib.util
+import json
+import re
+from pathlib import Path
+
+
+ROOT = Path(__file__).resolve().parents[1]
+
+
+def load_client():
+    path = ROOT / "public" / "kem_client.py"
+    spec = importlib.util.spec_from_file_location("nullroute_client", path)
+    module = importlib.util.module_from_spec(spec)
+    assert spec.loader is not None
+    spec.loader.exec_module(module)
+    return module
+
+
+def main() -> None:
+    client = load_client()
+    capsule = json.loads((ROOT / "public" / "capsule.json").read_text())
+    plaintext = client.decrypt_capsule(capsule).decode()
+    match = re.search(r"caplag\{[^}]+\}", plaintext)
+    if not match:
+        raise SystemExit("flag not found")
+    print(match.group(0))
+
+
+if __name__ == "__main__":
+    main()