We often hear of AES-128-CBF and AES-128-GCM, but what's the difference between them?

  • 1
    Can you be more specific? There are plenty of differences, which you can see from Wikipedia. Apr 7, 2019 at 16:27

1 Answer 1


That last part refers to the mode of operation of the cipher.

GCM is the Galois/Counter Mode which provides authenticity. You probably mean CFB for the first one, which is the Cipher Feedback Mode, an older and more simple one that provides no additional function.

The main differences between cipher modes is what they are optimized for and what features they provide. Many require an IV, but some only a nonce. Some leak patterns (ECB), most don't. GCM includes a MAC, most others don't. GCM is also optimized for performance.

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