A Conversation for Cryptography 2: Public Key Crypto

Can both keys always encrypt and decrypt?

Post 1

Sten

Hi Calroth,

you write, "But the remarkable thing is, only one of these keys can encrypt and only one can decrypt. (Actually, they can do both, but only one at a time.)"

Even if we can stipulate that the keys are related in subtle and earth-shattering (i.e., unexplained) ways, it it necessarily true that both keys can always encypt and decrypt?

That would assume that every possible ciphertext is also a possible plaintext and vice versa but that is not true of all public-key cryptosystems.

In spite of this, I think that this is an excellent article. It's the first article I know (outside of professional publications) that sets up public-key cryptography as a solution to the key distribution problem and not as a solution to an authentication problem.

Fun,

Sten


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Can both keys always encrypt and decrypt?

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