What is GCM? Galois Counter Mode (of operation) (usually seen as AES-GCM)

In this video I'm explaining what is that Galois Counter Mode that provides Authenticated Encryption with Associated Data (AEAD). You must have heard it combined with AES, and maybe used in TLS, ... This is just a small explanation, you can get more on the NIST specs.

To know more about ChaCha20(-Poly1305) check The book that I wrote Real-World Cryptography https://www.manning.com/books/real-wo...

00:00 Intro
00:39 ECB mode
02:05 CTR mode
03:35 Attack on CTR mode
04:35 Using a MAC
06:03 GMAC
09:45 AEAD
11:37 GF(2^128)
15:40 Outro

Errata (thanks to Casper Kejlberg-Rasmussen in the comments)

error at 11:21, the last M_H that is applied before going into the TAG should not be there if you compare your drawing to the diagram on https://en.wikipedia.org/wiki/Galois/....

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