How do different encryption schemes scale as a relation between their security parameter and computational requirement?

mnaei

5/5/24, 6:21 PM

For example is it harder to break one 256 bit encryption than two 255 bit encryption for RSA and AES?

For example, I understand that 256 bit RSA can be cracked in one minute according to this article [1] So would two independent 255 bit RSA message take thirty seconds each, and four 254 bit messages take 15 seconds each, etc... or would two 255 bit messages take 1 minute total on average?

[1] https://www.doyler.net/security-not-included/cracking-256-bit-rsa-keys

0 + 6

aes

Maarten Bodewes

5/5/24, 6:25 PM

As a starting point, why not just take a look at https://keylength.com, it links to the various methods that are used to calculate key strength. As for your (homework?) question, have you heard about meet-in-the-middle?

mnaei

5/5/24, 6:37 PM

Haha, not a homework question. I was just wondering if their key space is additive or if other interaction is at play. To clarify these are two different 255 bit encryption, not one message that has been encrypted twice. Thanks, I will look into meet-in-the-middle.

Maarten Bodewes

5/5/24, 7:04 PM

Could you please clarify your scheme in the question by hitting [edit]? 255 bit RSA is not secure.

mnaei

5/5/24, 8:20 PM

Will do. Sorry if the question is not clear. I understand that 256 bit RSA can be cracked in one minute according to this article [1] My question is about the rate of change as it relates to increasing the key length. So would two independent 255 bit RSA message take thirty seconds each, and four 254 bit messages take 15 seconds each, etc... [1] https://www.doyler.net/security-not-included/cracking-256-bit-rsa-keys

Maarten Bodewes

5/5/24, 8:27 PM

RSA and AES need to be used in a mode of operation to operate as a secure cipher. You cannot just say use RSA-255 twice with two different keys either. For one, usually the plaintext size needs to be significantly smaller for RSA to be secure, so the ciphertext of one RSA operation will likely not fit into another. Symmetric ciphers operate entirely differently from asymmetric ciphers, and may be vulnerable against meet-in-the-middle attacks as mentioned earlier. In other words, both the Q and the A may be more complex than you might imagine.

mnaei

5/5/24, 8:45 PM

Understood. I see that I require a more fundamental understanding of both schemes to ask the right question. I also found this wiki page [1] which kinda points me towards the right direction. Thanks for your help [1] https://en.wikipedia.org/wiki/RSA_numbers Thanks

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: How do different encryption schemes scale as a relation between their security parameter and computational requirement?

Post an answer

Most people don’t grasp that asking a lot of questions unlocks learning and improves interpersonal bonding. In Alison’s studies, for example, though people could accurately recall how many questions had been asked in their conversations, they didn’t intuit the link between questions and liking. Across four studies, in which participants were engaged in conversations themselves or read transcripts of others’ conversations, people tended not to realize that question asking would influence—or had influenced—the level of amity between the conversationalists.