I’ve been trying to get my head around this and I’ve watched a few videos but they don’t seem to specifically answer my question.

According to what I’ve found online, messages encrypted with a public key can only be decrypted with a private key. But in practice, how is that possible?

Surely a public key contains a set of instructions, and anyone could just run those instructions in reverse to decrypt a message? If everything you need to encrypt a message is stored within a public key, then how is it a one-way process?

It’s likely that I’m misunderstanding a core element of this!

  • OmegaMouseOP
    5·
    8 months ago

    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

    • rufus@discuss.tchncs.de
      4·
      8 months ago

      Both cryptography and that part of history are fascinating topics. I can also recommend watching “The Imitation Game” with Benedict Cumberbatch starring as Alan Turing… I mean it’s just a movie and skips lots of the interesting stuff and details. YMMV.

      It’s the beginning of computers. And I think especially that time has some interesting stories, discoveries/inventions and personas. There is also the history and role of women in computing which I think is something more people should know about and it’s related to that. After that we needed secrecy in the cold war. I think public key cryptography hasn’t been around until the 1970s. There had been export regulations on cryptography until after I was born. And modern encryption algorithms like AES are from the 1990s. Nowadays everyone and their grandma relies on the availability of secure communications.

      I think I spent some nights jumping from Wikipedia article to Wikipedia article and reading all of that.