New answers tagged gcm
One of the major advantages of GCM is the authenticated data input that you can pass. Think about headers of a message that you want authenticated but not encrypted. This is a great thing to have in many practical implementations where some data has to stay in clear but manipulating it by an attacker has serious consequences.
Unless you are absolutely sure that you don't need to and that the cost is going to be significant then I would absolutely say you should use authenticated encryption. One reason is bit-flipping attacks - flipping a few bits at the 'right' point in your encrypted message might lead well to a message that is legal (the classic example is if someone learns ...
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