ALL the CTFS of Crypto2025 finally

crypto-simmetric/guess-mode-one-shot/ECBvsCBCClient.py

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+import os
+os.environ['PWNLIB_NOTERM'] = 'True'  # Configuration patch to allow pwntools to be run inside of an IDE
+os.environ['PWNLIB_SILENT'] = 'True'
+
+from pwn import *
+from math import ceil
+from Cryptodome.Cipher import AES
+
+#from myconfig import HOST,PORT
+
+
+
+BLOCK_SIZE = AES.block_size
+BLOCK_SIZE_HEX = 2*BLOCK_SIZE
+
+HOST = "130.192.5.212"
+PORT = "6531" 
+
+server = remote(HOST, PORT)
+
+# stole from the server code...
+# message = "This is what I received: " + msg + " -- END OF MESSAGE"
+start_str = "This is what I received: "
+# print(len(start_str))
+pad_len = ceil(len(start_str)/BLOCK_SIZE)*BLOCK_SIZE-len(start_str)
+
+msg = b"A"*(16*2+pad_len) #2 * AES.block_size + oad_len
+print("Sending: "+str(msg))
+server.send(msg)
+
+
+ciphertext = server.recv(1024)
+ciphertext_hex = ciphertext.hex()
+print(ciphertext_hex)
+
+server.close()
+
+for i in range(0,int(len(ciphertext_hex)//BLOCK_SIZE_HEX)):
+    print(ciphertext_hex[i*BLOCK_SIZE_HEX:(i+1)*BLOCK_SIZE_HEX])
+
+
+print("Selected mode is", end=' ')
+if ciphertext[2*BLOCK_SIZE:3*BLOCK_SIZE] == ciphertext[3*BLOCK_SIZE:4*BLOCK_SIZE] :
+    print("ECB")
+else:
+    print("CBC")