Curve25519 simple key exchange approach What is a simple approach in Curve25519 key exchange in basic steps?
Alice and Bob choose their secret scalars $a,b \in \{0,1\}^{|p|}$.
They compute their public keys $Ga$ and $Gb$ and send the public key to the other.
Alice computes the shared key $k = \text{kdf}(Gba)$ and Bob computes the shared key $k = \text{kdf}(Gab)$.





They can use this established key $k$ as their shared symmetric key. I.e. Use it as the key for AES-PMAC-SIV to send variable-length messages that are both authenticated end encrypted.




Eve is allowed to learn all public keys and ciphertexts. Assuming that at least the Computation Diffie-Hellman and Discrete Logarithm problems are hard, then she cannot recover the shared key.