ALL the CTFS of Crypto2025 finally

crypto-simmetric/guess-mode-double-shot/chall.py

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+from Cryptodome.Cipher import AES
+from Cryptodome.Random import get_random_bytes
+#from secret import flag
+import random
+flag="puppa"
+modes_mapping = {
+    "ECB": AES.MODE_ECB,
+    "CBC": AES.MODE_CBC
+}
+
+
+class RandomCipherRandomMode():
+    def __init__(self):
+        modes = [AES.MODE_ECB, AES.MODE_CBC]
+        self.mode = random.choice(modes)
+        self.key = get_random_bytes(32)
+        if self.mode == AES.MODE_ECB:
+            self.iv = None
+            self.cipher = AES.new(key=self.key, mode=self.mode)
+        else:
+            self.iv = get_random_bytes(16)
+            self.cipher = AES.new(key=self.key, iv=self.iv, mode=self.mode)
+
+    def encrypt(self, data):
+        return self.cipher.encrypt(data)
+
+    def decrypt(self, data):
+        return self.cipher.decrypt(data)
+
+
+def main():
+
+    for i in range(128):
+        cipher = RandomCipherRandomMode()
+
+        print(f"Challenge #{i}")
+
+        data = b"\00"*32
+
+        otp = get_random_bytes(len(data))
+        #I dont know the OTP generated
+        for _ in range(2):
+            print(f"The otp is:{otp.hex()}")
+            #data = bytes.fromhex(input("Input: ").strip())
+            if len(data) != 32:
+                print("Data must be 32 bytes long")
+                return
+            data = bytes([d ^ o for d, o in zip(data, otp)])
+            print(f"Output: {cipher.encrypt(data).hex()}")
+        mode_test = input(f"What mode did I use? (ECB, CBC)\n")
+        if mode_test in modes_mapping.keys() and modes_mapping[mode_test] == cipher.mode:
+            print("OK, next")
+        else:
+            print("Wrong, sorry")
+            return
+
+    print(f"The flag is: {flag}")
+
+
+if __name__ == "__main__":
+    main()