3 ms·

Speaking as a total novice, I've always found OTPs attractive. Wish you had made a better argument here, for perhaps I'm missing it. Yep, key management is a p

Speaking as a total novice, I've always found OTPs attractive. Wish you had made a better argument here, for perhaps I'm missing it. Yep, key management is a problem. That's all I got, and I know there had to be more. Do you know of any longer treatments of this subject? Sure would love to read them. I mean, I'm thinking if I want to share data with a friend, I get a hardware true RNG, cut a couple of 1TB SSDs full of random noise, and hand him a copy. With that amount of data, I'm thinking he and I are good to go for the rest of our lives. (Of course, commercial applications have other constraints)

_fizz_buzz_ 11y ago
Here is the thing, the cryptography is really not the weak part of a communication system. You really don't gain anything by using a one-time pad over something like AES-256 in any practical sense. You're only making the part of your system stronger that is already more than strong enough (From a thermodynamics point of view you couldn't even brute force AES-256 if you had a supernova as an energy source [1]). Difficult parts of a secure communication system are authentication, key-exchange, etc. Example how to compromise your system: I send your friend a message with some random data and pretend to be you. Now he doesn't know what's going on and you two are out of sync and cannot securely re-sync your keys without meeting up again. [1] https://www.schneier.com/blog/archives/2009/09/the_doghouse_cr.html https://www.schneier.com/blog/archives/2009/09/the_doghouse_...
- ryacko 11y ago
  You can bruteforce AES-256 if you were using a quantum computer. Or if there's a new advance in algebraic cryptanalysis.
  - _fizz_buzz_ 11y ago
    > You can bruteforce AES-256 if you were using a quantum computer. Not true. AES does not suffer from the same weaknesses as many public key schemes. A quantum computer could speed up an attack on AES, but does not fundamentally break it. > Or if there's a new advance in algebraic cryptanalysis. Sure. But my point was that there are much weaker points than the encryption in a communication system.
sarciszewski 11y ago
> Wish you had made a better argument here, for perhaps I'm missing it. I did have a better argument here. It was point 2. Unauthenticated encryption is dangerous: https://paragonie.com/blog/2015/05/using-encryption-and-authentication-correctly https://paragonie.com/blog/2015/05/using-encryption-and-auth...

_fizz_buzz_ 11y ago

Here is the thing, the cryptography is really not the weak part of a communication system. You really don't gain anything by using a one-time pad over something like AES-256 in any practical sense. You're only making the part of your system stronger that is already more than strong enough (From a thermodynamics point of view you couldn't even brute force AES-256 if you had a supernova as an energy source [1]). Difficult parts of a secure communication system are authentication, key-exchange, etc. Example how to compromise your system: I send your friend a message with some random data and pretend to be you. Now he doesn't know what's going on and you two are out of sync and cannot securely re-sync your keys without meeting up again. [1] https://www.schneier.com/blog/archives/2009/09/the_doghouse_cr.html https://www.schneier.com/blog/archives/2009/09/the_doghouse_...

ryacko 11y ago
You can bruteforce AES-256 if you were using a quantum computer. Or if there's a new advance in algebraic cryptanalysis.
- _fizz_buzz_ 11y ago
  > You can bruteforce AES-256 if you were using a quantum computer. Not true. AES does not suffer from the same weaknesses as many public key schemes. A quantum computer could speed up an attack on AES, but does not fundamentally break it. > Or if there's a new advance in algebraic cryptanalysis. Sure. But my point was that there are much weaker points than the encryption in a communication system.

sarciszewski 11y ago

> Wish you had made a better argument here, for perhaps I'm missing it. I did have a better argument here. It was point 2. Unauthenticated encryption is dangerous: https://paragonie.com/blog/2015/05/using-encryption-and-authentication-correctly https://paragonie.com/blog/2015/05/using-encryption-and-auth...