project sekai 2023

Project Sekai 2023/Cryptography/cryptoGRAPHy 1/server.py

@@ -0,0 +1,50 @@
+from lib import GES, utils
+import networkx as nx
+import random
+
+from SECRET import flag, decrypt
+
+NODE_COUNT = 130
+EDGE_COUNT = 260
+SECURITY_PARAMETER = 16
+
+def gen_random_graph(node_count: int, edge_count: int) -> nx.Graph:
+    nodes = [i for i in range(1, node_count + 1)]
+    edges = []
+    while len(edges) <  edge_count:
+        u, v = random.choices(nodes, k=2)
+        if u != v and (u, v) not in edges and (v, u) not in edges:
+            edges.append([u, v])
+    return utils.generate_graph(edges)
+
+if __name__ == '__main__':
+    try:
+        print("[+] Generating random graph...")
+        G = gen_random_graph(NODE_COUNT, EDGE_COUNT)
+        myGES = GES.GESClass(cores=4, encrypted_db={})
+        key = myGES.keyGen(SECURITY_PARAMETER)
+        print(f"[*] Key: {key.hex()}")
+
+        print("[+] Encrypting graph...")
+        enc_db = myGES.encryptGraph(key, G)
+
+        print("[!] Answer 50 queries to get the flag. In each query, input the shortest path \
+              decrypted from response. It will be a string of space-separated nodes from \
+              source to destination, e.g. '1 2 3 4'.")
+        for q in range(50):
+            while True:
+                u, v = random.choices(list(G.nodes), k=2)
+                if nx.has_path(G, u, v):
+                    break
+            print(f"[+] Query {q+1}/50: {u} {v}")
+            token = myGES.tokenGen(key, (u, v))
+            _, resp = myGES.search(token, enc_db)
+            print(f"[*] Response: {resp.hex()}")
+
+            ans = input("> Original query: ").strip()
+            if ans != decrypt(u, v, resp, key):
+                print("[!] Wrong answer!")
+                exit()
+        print(f"[+] Flag: {flag}")
+    except:
+        exit()