cryptography-core/dev.whyoleg.cryptography.algorithms/ECDH

ECDH

@SubclassOptInRequired(markerClass = [CryptographyProviderApi::class])

interface ECDH : EC<ECDH.PublicKey, ECDH.PrivateKey, ECDH.KeyPair> (source)

Elliptic Curve Diffie-Hellman (ECDH) key agreement as defined in NIST SP 800-56A.

ECDH allows two parties to establish a shared secret over an insecure channel using elliptic curve keys. Each party generates a key pair on the same EC.Curve, then computes the shared secret using their own private key and the other party's public key.

val aliceKeys = provider.get(ECDH).keyPairGenerator(EC.Curve.P256).generateKey()
val bobKeys = provider.get(ECDH).keyPairGenerator(EC.Curve.P256).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 Montgomery curves, see XDH.

Types

Companion

object Companion : CryptographyAlgorithmId<ECDH>

KeyPair

@SubclassOptInRequired(markerClass = [CryptographyProviderApi::class])

interface KeyPair : EC.KeyPair<ECDH.PublicKey, ECDH.PrivateKey>

PrivateKey

@SubclassOptInRequired(markerClass = [CryptographyProviderApi::class])

interface PrivateKey : EC.PrivateKey<ECDH.PublicKey>

An ECDH private key that provides shared secret computation via sharedSecretGenerator.

PublicKey

@SubclassOptInRequired(markerClass = [CryptographyProviderApi::class])

interface PublicKey : EC.PublicKey

An ECDH public key that provides shared secret computation via sharedSecretGenerator.

Properties

open override val id: CryptographyAlgorithmId<ECDH>

The typed identifier that uniquely distinguishes this algorithm and is used to look it up from a CryptographyProvider.

Functions

keyPairGenerator

abstract fun keyPairGenerator(curve: EC.Curve): KeyGenerator<ECDH.KeyPair>

Returns a KeyGenerator that generates EC key pairs on the given curve.

privateKeyDecoder

abstract fun privateKeyDecoder(curve: EC.Curve): Decoder<EC.PrivateKey.Format, ECDH.PrivateKey>

Returns a Decoder that decodes EC private keys on the given curve from the specified PrivateKey.Format.

publicKeyDecoder

abstract fun publicKeyDecoder(curve: EC.Curve): Decoder<EC.PublicKey.Format, ECDH.PublicKey>

Returns a Decoder that decodes EC public keys on the given curve from the specified PublicKey.Format.