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set1/challenge5.py

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+
+def repeating_key_xor(key, message):
+    key_length = len(key)
+    message_length = len(message)
+    expanded_key = (key * (int(message_length / key_length))) + key[:message_length % key_length]
+    return bytes([m ^ k for m, k in zip(message, expanded_key)])
+
+message = "Burning 'em, if you ain't quick and nimble\nI go crazy when I hear a cymbal"
+key = "ICE"
+
+# Convert message and key to bytes
+message = message.encode('utf-8')
+key = key.encode('utf-8')
+
+cipher = repeating_key_xor(key, message)
+
+# Convert to hexadecimal
+cipher_hex = cipher.hex()
+
+print(cipher_hex)