cryptopals

commit 931e3bc27e51dadfb856737a201ab74697fd7533
parent 05e2ca10d3d3700e70642e27eda6a4580b20458b
Author: mpizzzle <michael.770211@gmail.com>
Date:   Tue, 31 Oct 2017 21:16:41 +0000

set 3 challenge 18 complete

Diffstat:
A
set3/aes_in_ctr_mode.py
 | 
18
++++++++++++++++++

1 file changed, 18 insertions(+), 0 deletions(-)
diff --git a/set3/aes_in_ctr_mode.py b/set3/aes_in_ctr_mode.py
@@ -0,0 +1,18 @@
+from Crypto.Cipher import AES
+
+ciphertext = "L77na/nrFsKvynd6HzOoG7GHTLXsTVu9qvY/2syLXzhPweyyMTJULu/6/kXX0KSvoOLSFQ==".decode("base64")
+blocks = [ciphertext[i:i + AES.block_size] for i in range(0, len(ciphertext), AES.block_size)]
+
+key = "YELLOW SUBMARINE"
+aes = AES.new(key, AES.MODE_ECB)
+
+nonce = ''.join(['\x00' for i in range(AES.block_size / 2)])
+block_count = ['\x00' for i in range(AES.block_size / 2)]
+
+plaintext = ""
+
+for block in blocks:
+    plaintext += ''.join([chr(ord(a) ^ ord(b)) for a, b in zip(block, aes.encrypt(nonce + ''.join(block_count)))])
+    block_count[0] = chr((ord(block_count[0]) + 1) % 256) #you get the point
+
+print plaintext