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?