ALL the CTFS of Crypto2025 finally

crypto-simmetric/force-decryption/chall.py

@@ -0,0 +1,77 @@
+from Cryptodome.Cipher import AES
+from Cryptodome.Random import get_random_bytes
+#from secret import flag
+
+key = get_random_bytes(16)
+leak = b"mynamesuperadmin"
+
+
+def make_cipher():
+    IV = get_random_bytes(16)
+    cipher = AES.new(key, AES.MODE_CBC, IV=IV)
+    return IV, cipher
+
+
+def encrypt():
+    string = input("What do you want to encrypt?\n> ")
+    #string = leak
+    #stringX = bytes(([s ^ 1 for s in string]))
+    string = bytes.fromhex(string)
+    #string = stringX
+    if len(string) != 16:
+
+        print("Sorry, you can encrypt only 16 bytes!")
+        return
+
+    if leak == string:
+        print("Sorry, you can't encrypt that!")
+        return
+
+    IV, cipher = make_cipher()
+    encrypted = cipher.encrypt(string)
+
+    print(F"IV: {IV.hex()}\nEncrypted: {encrypted.hex()}\n")
+
+
+def decrypt():
+    string = input("What do you want to decrypt?\n> ")
+    string = bytes.fromhex(string)
+
+    IV = input("Gimme the IV\n> ")
+    IV = bytes.fromhex(IV)
+
+    if (IV == leak):
+        print("Nice try...")
+        return
+
+    cipher = AES.new(key, AES.MODE_CBC, IV=IV)
+
+    decrypted = cipher.decrypt(string)
+    if leak == decrypted:
+        print(f"Good job. Your flag: PUPPA")
+    else:
+        print(f"Mh, a normal day.\nDecrypted: {decrypted.hex()}")
+
+
+if __name__ == '__main__':
+    menu = \
+        "What do you want to do?\n" + \
+        "quit - quit the program\n" + \
+        "enc - encrypt something\n" + \
+        "dec - decrypt something\n" + \
+        "help - show this menu again\n" + \
+        "> "
+
+    while True:
+        cmd = input(menu).strip()
+
+        if cmd == "quit":
+            break
+        elif cmd == "help":
+            continue
+        elif cmd == "enc":
+            encrypt()
+        elif cmd == "dec":
+            decrypt()
+        elif cmd == "crack":
+            decrypt(encrypt())