AES Encryption Modes

Discussions critique insecure uses of AES in modes like CBC without authentication, compare to GCM or CTR, and highlight vulnerabilities like nonce reuse, known-plaintext attacks, and padding oracles.

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Keywords

e.g GCM MAC US CPU LLM AEAD encrypt.c FDE OK aes encryption key mode attacks pad encrypt secure plaintext construction

Sample Comments

wkornewald Jun 25, 2013 View on HN

Doesn't this make your key susceptible to known-plaintext attacks?

CiPHPerCoder May 23, 2017 View on HN

CBC mode isn't exactly a saving grace here, since it's unauthenticated.

1718627440 Sep 23, 2025 View on HN

That's just encryption with a one-time pad, nothing new...

Osmium Sep 23, 2015 View on HN

Doesn't this depend on the mode of operation/block chaining? Or is it an issue regardless?

SAI_Peregrinus Jul 25, 2021 View on HN

It doesn't use CBC mode or dynamically pick key sizes, so it can't be.

tptacek Jul 4, 2025 View on HN

The AES block cipher core: also grievously insecure if used naively, without understanding what a block cipher can and can't do, by itself. Thus also an LLM call.

tptacek Feb 14, 2017 View on HN

Why did you use CBC? It's actually harder than crypto/cipher.AEAD, and what you're doing now seems insecure.

andrewpe Jan 2, 2017 View on HN

Might need to read up on modern ciphers. They are protected against this kind of attack.

tptacek Apr 11, 2014 View on HN

Yes, look at Rogaway's license for OCB mode.

RA2lover Jun 13, 2024 View on HN

If the attacker never gets a hold of a plaintext-ciphertext pair, how well does AES-GCM with nonce reuse hold up?