Understanding how AES encryption works
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Understanding how AES encryption works
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Re: Understanding how AES encryption works
#2I don't want to snipe but it's a peeve of mine: every article about AES talks about SubBytes and ShiftRows or whatever, which is information you will never, ever use, even if your career takes a turn into cryptography engineering, but nobody talks about block cipher modes, which are basically the most important thing you can know about block cryptography.
Re: Understanding how AES encryption works
#3I don't want to snipe but it's a peeve of mine: every article about AES talks about SubBytes and ShiftRows or whatever, which is information you will never, ever use , even if your career takes a turn into cryptography engineering, but nobody talks about block cipher modes, which are basically the most important thing you can know about block cryptography.
To be fair, I'm not in cryptography engineering and had to understand all those details for an implementation security review.
But I completely agree on the block cipher modes thing, a lot of people don't realize what they are doing and just use whatever sounds good, even if it is ECB and it is not relevant in the context.
Re: Understanding how AES encryption works
#4I don't want to snipe but it's a peeve of mine: every article about AES talks about SubBytes and ShiftRows or whatever, which is information you will never, ever use , even if your career takes a turn into cryptography engineering, but nobody talks about block cipher modes, which are basically the most important thing you can know about block cryptography.
The implementation of AES isn't even that interesting; it's not especially clever and doesn't leverage any deep mathematical principles. You can learn a lot more reading about cipher modes, as you mention. See GCM for a very interesting one.
Re: Understanding how AES encryption works
#5> I don't want to snipe but it's a peeve of mine: every article about AES talks about SubBytes and ShiftRows or whatever, which is information you will never, ever use, even if your career takes a turn into cryptography engineering, but nobody talks about block cipher modes, which are basically the most important thing you can know about block cryptography.
This article is called, "Understanding how AES works". Are you upset that the author wrote such a paper? This paper isn't intended to explain how to use AES. Rather it is intended to satisfy the readers curiosity about how it works.
Re: Understanding how AES encryption works
#6I don't want to snipe but it's a peeve of mine: every article about AES talks about SubBytes and ShiftRows or whatever, which is information you will never, ever use , even if your career takes a turn into cryptography engineering, but nobody talks about block cipher modes, which are basically the most important thing you can know about block cryptography.
To be fair, I'm not in cryptography engineering and had to understand all those details for an implementation security review. But I completely agree on the block cipher modes thing, a lot of people don't realize what they are doing and just use whatever sounds good, even if it is ECB and it is not relevant in the context.
Can you say something the circumstances that lead to a security review of something that implements its own AES and that implementation is reviewed by (self-described) nonspecialists?
Re: Understanding how AES encryption works
#7shameless plug: if you want to learn how it works, implement it! There's a tutorial for that: https://davidwong.fr/blockbreakers/aes.html
Re: Understanding how AES encryption works
#8This is my "textbook" implementation of AES128, which follows the FIPS specification as closely as possible (in python): https://github.com/DavidBuchanan314/aes-playground
It also includes from-scratch Galois field arithmetic functions.
Re: Understanding how AES encryption works
#9shameless plug: if you want to learn how it works, implement it! There's a tutorial for that: https://davidwong.fr/blockbreakers/aes.html
That tutorial looks really cool. I'm slightly concerned with the tutorial leaving the implementation details to the user, and the tutorial basically saying:
"Remember: to test your function, you can use the test vectors from the appendix A.1 of the AES standard. "
Bad AES implementations suffer from variety of attacks including cache timing attacks etc. and since you've worked for NCC etc. I'm sure you know a ton about this including about cache timing attacks. The guide isn't ready yet, and given that there's upcoming parts about linear/differential cryptanalysis of AES, it might actually be beneficial to have a weak implementation to attack later to show why AES shouldn't be written from scratch.
While the writing about the attacks is in the works, in your opinion, would it be worth underlining that the implementation the reader has produced should not be used in production, and that the user has only produced an educational textbook version to learn the basics about the cipher?
Re: Understanding how AES encryption works
#10I don't want to snipe but it's a peeve of mine: every article about AES talks about SubBytes and ShiftRows or whatever, which is information you will never, ever use , even if your career takes a turn into cryptography engineering, but nobody talks about block cipher modes, which are basically the most important thing you can know about block cryptography.
To be fair, I'm not in cryptography engineering and had to understand all those details for an implementation security review. But I completely agree on the block cipher modes thing, a lot of people don't realize what they are doing and just use whatever sounds good, even if it is ECB and it is not relevant in the context.
It's always this: AES-CBC with
1) no authentication whatsoever, or
2) fixed IV, "but it's random, I threw the dices myself!!", or
3) fixed key, no forward secrecy of any kind