Is using the same IV in AES similar to not using an IV in the first place?
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So if I understand how an IV works with AES, I'm supposed to generate a different IV for every message because using only a key, I will get the same encryption if the message was encrypted twice (which is not secure) thus we use the IV which is some kind of a salt (some random bytes added to the encrypted message so 2 messages with the same value won't have the same encryption).
For one, the IV is not specifically related to AES at all. AES is a keyed invertible transform from a 128 bit value to a 128 bit value; that's all it can do. Now, if you just happen to have a 128 bit value that you want 'encrypted' into a 128 bit ciphertext, well, you can just use AES as is.
