DH

Classic finite-field Diffie-Hellman (DH) key agreement as defined in RFC 2631.

DH allows two parties to establish a shared secret over an insecure channel using arithmetic in a finite field defined by domain Parameters. Parameters must be generated via parametersGenerator or decoded via parametersDecoder before key pairs can be created. RFC 3526 defines well-known groups that can be decoded from their standard representations.

val params = provider.get(DH).parametersGenerator(2048.bits).generateParameters()
val aliceKeys = params.keyPairGenerator().generateKey()
val bobKeys = params.keyPairGenerator().generateKey()
val sharedSecret = aliceKeys.privateKey.sharedSecretGenerator().generateSharedSecret(bobKeys.publicKey)

The raw shared secret output should not be used directly as a key. Use a key derivation function like HKDF to derive actual keys from the shared secret.

For key agreement using elliptic curves, see ECDH. For Montgomery curves, see XDH.