Oddbean new post about login | logout If I wanted to encrypt some plain text into cipher text using a key pair from the secp256k1 curve, such that multiple parties would be able to decrypt it with their own keys, how would I do that?
DH key exchange to generate a shared common secret?
This is good for Alice and Bob. I want to include Charlie, Dianne, Emily, Fred, Geoff, Harry, Ingrid, etc etc
Can't you repeat it N-1 times?
Shared secret would no longer be secret
I would do what PGP does, which is symmetrically encrypt the message, and then encrypt the symmetric key multiple times, once to each recipient, via ECDH, putting that alongside the message.
This is a great solution, thank you.
Need a bit more specifics. ECDH handles this already like we do in nip04 and nip44. This would require encrypting the plaintext for each person then passing it. There is really no way to avoid that. You will have to share some piece of information individually with each user. If you opt for the nip04/nip44 mechanisms then the user's already have the required information needed for encryption/decryption. There would be no "universal decryption" mechanism where you can have the same ciphertext encrypted in such a way that a select group of users would be able to decrypt.
That's what I thought. Thanks.
Why?