cryptopals

commit d85b31355c22108c59285856e103d9f9def67992
parent 931e3bc27e51dadfb856737a201ab74697fd7533
Author: mpizzzle <michael.770211@gmail.com>
Date:   Tue, 31 Oct 2017 21:23:35 +0000

refactoring ctr encryption into method

Diffstat:
M
set3/aes_in_ctr_mode.py
 | 
20
++++++++++----------

1 file changed, 10 insertions(+), 10 deletions(-)
diff --git a/set3/aes_in_ctr_mode.py b/set3/aes_in_ctr_mode.py
@@ -1,18 +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 = ""
+def encrypt(ciphertext, key, nonce):
+    aes = AES.new(key, AES.MODE_ECB)
+    block_count = ['\x00' for i in range(AES.block_size / 2)]
+    plaintext = ""
+
+    for block in [ciphertext[i:i + AES.block_size] for i in range(0, len(ciphertext), AES.block_size)]:
+        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
 
-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
+    return plaintext
 
-print plaintext
+print encrypt(encrypt(encrypt(ciphertext, key, nonce), key, nonce), key, nonce)