OmegaMouse

It looks more like a solar eclipse in that panel than a lunar eclipse. So I was wondering if it's possible to have a solar eclipse at midnight. And yes it is!

This eclipse will start only a few hours after the northern solstice and most of the path will go across areas with midnight sun

Ah thanks for the useful links! Those articles are all quite fascinating. In the plaintext attacks article, I love the tactic mentioned here:

At Bletchley Park in World War II, strenuous efforts were made to use (and even force the Germans to produce) messages with known plaintext. For example, when cribs were lacking, Bletchley Park would sometimes ask the Royal Air Force to "seed" a particular area in the North Sea with mines (a process that came to be known as gardening, by obvious reference). The Enigma messages that were soon sent out would most likely contain the name of the area or the harbour threatened by the mines

I explained it poorly - what I mean to say is, two people trying to send the message 'Hello' for example both using the same public key would get the same output. So if you had a simple message like that, someone could work out by checking every word in the dictionary what your message was by checking if the output matched.

But I guess it's a bit of a moot point - it's unlikely that an encrypted message would ever be so simple. It could just as easily be much longer, and therefore basically impossible to guess the plaintext.

Ah I think of sort of get it!

The public key is used within a function by the person sending the message, and even someone that knew the function and the public key wouldn't be able to decrypt the message, because doing so would require knowledge of the original prime numbers which they couldn't work out unless a computer spend years factoring the public key.

My only other bit of confusion:

• If someone used a public key to encrypt the message "Hello", maybe it would spit out something like Gh5bsKjbi4
• If someone else sent the exact same message I assume the outcome would also be identical, and therefore it would be possible by using common phrases to work out what was sent? I could type messages like Hi, Goodbye, Hola until I got to 'Hello' and realised it was the same output.
• However I assume that a message like 'Hello, how are you?' would result in a completely different output (despite Hello appearing in both) and thus trying to work out any messages in a brute force way like this would be pointless.

So using the formula in that guide, you get a numerical value for O. But surely someone else could follow the same process and also get the same answer? Unless the primes change each time? But then how would the sender and receiver know the way in which the values change?

But say (simplying greatly) the public key tells my computer to multiply my text by a prime number

If the prime number is already known from the public key, then why is any computation required? To decrypt it can't I (or anyone else) just divide by the prime? Even with a significantly more complex calculation, can't you just work the steps back in reverse using the instructions from the public key?

I'm not familiar with this work, but it seems like a fascinating topic and still as relevant today as it was back then. Thanks for the summary/review.

I guess something like this (data stored on glass plates 'Project Silica') would store the data safely for a much longer period. What I'm not entirely clear on is whether it would still be possible to read that data in the far future - it seems to rely on some kind of machine learning to decode it.

Do you reckon the physical copies would last longer than digital?

Ah gotcha! Yeah it's pretty neat seeing the ways in which the instances intermingle. Some communities stay pretty niche and used only by local users with the same interests, whereas others are melting pots of every instance. I guess it's a bit like a society with little towns and bigger cities.

Root federated?

Thanks, this is a good summary. It's useful to know about the dynamically changing route - that explains a lot.