CODEWITHSUNDEEP
pythoncencryptionpublic-key-encryption
pefu
pefu

Reputation: 480

How to exchange and authenticate ephemeral public keys with tweetnacl?

The C library http://tweetnacl.cr.yp.to/ for strong ECC encryption written and published by Daniel J.Bernstein is very neat and small.

Using it from Python is even easier with the tweetnacl Python interface module written and published by Jan Mojžíš : https://mojzis.com/software/python-tweetnacl/index.html

Generating ephemeral public and secret key pairs is very easy: 

python
>>> import tweetnacl as nacl
>>> pk, sk = nacl.crypto_box_keypair()

Assuming Alice got Bobs public key and vice versa then encrypted communication using the crypto_box() and crypto_box_open() functions is pretty straight forward and easy to implement.

But I wonder: What is easiest way to get Alice "pk" from here to Bob and the public key of Bob back to Alice? How can Bob be sure that a received public key is really the key of Alice and vice versa?

Upvotes: 1

Views: 541

Answers (1)

Mizstik
Mizstik

Reputation: 666

You can't without a trusted third party and another secure channel. That is the reason SSL has certificate authorities and trust-chain certificates pre-deployed in the browser. Without those, the exchange process is vulnerable to an active man in the middle.

Upvotes: 1

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