Hello i have just recently started learning about cryptography, so i was doing some little research on what kind of encryption techniques and modes that were used in bank web pages. I have noticed that some bank uses the AES_256_CBC with HMAC SHA1 and banks that uses AES_128_GCM...I have seen more banks using AES_128_GCM or AES_128_CBC over AES_256_CBC... So i would like to ask if there are any major advantages of using AES_128_GCM/CBC over AES_256_CBC or they are more or less the same and it is just a preferential


marked as duplicate by otus, Henrick Hellström, SEJPM, e-sushi Nov 29 '15 at 22:05

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  • $\begingroup$ GCM is indeed better than CBC, because CBC had issues in the past and GCM mitigates them (CBC authenticates-then-encrypts, GCM does it the other way around). Besides that speed is the major concern I'd guess (especially considering that banks may need to serve many connections at once). AES-128 is faster than AES-256 and today neither of both can be broken. $\endgroup$ – SEJPM Nov 29 '15 at 15:45
  • $\begingroup$ Oh i see so both are secured is just 128 is faster ! Thank you very much for the reply :) $\endgroup$ – Sean95 Nov 29 '15 at 15:49
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    $\begingroup$ The CBC vs. GCM part in answered here: crypto.stackexchange.com/questions/2310/… $\endgroup$ – otus Nov 29 '15 at 16:38

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