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Comment by bee_rider | Hacker News Reader

It depends on what you are transmitting, right?

Hypothetically if you are a journalist working with communications from a source in an authoritarian country (or a country that could become authoritarian in the next 4 decades; and name one that couldn’t, right?) it would be no good if you got some elderly person killed in the future.

Or just like bank account details I guess?

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No cryptographic scheme remains unbreakable forever. If what you want is permanent protection, cryptography is not the solution. If people are encrypting things expecting that encryption will never be broken, they're misusing encryption.

The point of cryptography isn't to keep secrets forever, it's to keep secrets for long enough that by the time those secrets are revealed, they are worthless.

I think this is a topic that much cleverer people than me have thought long and hard on. Of course nothing practical remains unbreakable forever, but it seems weird that for example the default key size for ssh-keygen isn’t in the “probably two lifetimes” range.

> No cryptographic scheme remains unbreakable forever. If what you want is permanent protection, cryptography is not the solution.

Whilst this has historically been true, it's very plausible that AES-256 means that (for this limited problem, symmetric encryption) we're done.

The "obvious" attack (some type of brute force) on AES-256, even assuming you have a quantum computer (which we don't) and it's actually more affordable than our current computers (which it won't be) is not practical in our universe.

I can tell you that journalists aren't worrying about that most of the time. It's very much outside their threat model in the majority of cases, as it should be - there's no way to feasibly predict and protect against cryptographic risks 30+ years from now.

In that case the volume of traffic such a communication medium would need to handle is likely small enough that you can bump the key size higher to ensure greater longevity, currently past the lifetimes of those involved, and accept that transmitting data will take a small fraction of time longer.

If extreme security is needed it’s time to turn off your computer, leave your cellphone at home, don’t tell details to colleagues who do not have a need to know, and maybe resort to dead drop methods so even you don’t know who the source is yourself.

Some people are willing to take a on some extra risk to talk to journalists, and the world is a better place for their bravery.

And we’re talking about thousands of bits, we spend way more than that on stupid things like making UI slightly prettier. I’m streaming music at, I guess, ~200kbps, why not spend a couple seconds worth of music on keys? (Who knows, maybe it will protect some famous journalist somehow and we’ll end up ahead when it spares us a whole moment of silence).

Edit: TBH I’m not really sure this is a useful way to look at things, but the music bandwidth/moment of silence parallel was too convenient to pass up.

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