Encryption with public key then decryption with private key

jedisct1 / libhydrogen

A lightweight, secure, easy-to-use crypto library suitable for constrained environments.

https://libhydrogen.org

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Encryption with public key then decryption with private key #18

Closed edubois closed 6 years ago

edubois commented 6 years ago

Hi again,

I read the doc, but I'm trying to do something customized. I need:

Something so that I can encode with the PUB public key but can't decrypt the stream with the same PUB key.
When something is encrypted with the PUB key, it can be decrypted with the PRV private key.

I also need the reciprocity (something encoded with PRV is decryptable by the PUB)

Is it something I can do with your library?

Thanks,

jedisct1 commented 6 years ago

Encrypting with your own public key is equivalent to symmetric encryption.

So I assume you want to encrypt using another party's public key instead, and that other party will use its private key to decrypt the content.

Use the Noise N variant: https://github.com/jedisct1/libhydrogen/wiki/N-variant to get a shared key. Encrypt using that shared key, and wipe that shared key. That shared key can be later recovered using the initiator's public key and the receiver's secret key.