EcdhKeyDerivation class ECDH

Performs ECDH key agreement and key derivation.

Use deriveKey to produce raw derived bytes via HKDF, or deriveAesKey to get a FortisAesKey directly.

For raw shared secret bytes (without HKDF), use deriveSharedSecret.

final pair = await Fortis.ecdh().generateKeyPair();
final theirPublicKey = (await Fortis.ecdh().generateKeyPair()).publicKey;

final derivation = Fortis.ecdh()
    .curve(EcdhCurve.p256)
    .keyDerivation(pair.privateKey);

// Derive raw key bytes
final keyBytes = derivation.deriveKey(theirPublicKey);

// Derive an AES key directly
final aesKey = derivation.deriveAesKey(theirPublicKey);

// Or get the raw shared secret
final secret = derivation.deriveSharedSecret(theirPublicKey);

See also:

• EcdhBuilder.keyDerivation, which builds this type with a validated key size.
• FortisEcdhPublicKey, the peer key every derivation takes.
• FortisAesKey, the symmetric key deriveAesKey returns.
• EcdhCurve, which both keys must agree on.

Constructors

EcdhKeyDerivation({required FortisEcdhPrivateKey privateKey, int keySize = 256})

Creates an EcdhKeyDerivation with the given privateKey and optional keySize in bits (default 256).

Properties

hashCode → int

The hash code for this object.

no setter, inherited

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

Methods

deriveAesKey(FortisEcdhPublicKey publicKey, {Uint8List? salt, Uint8List? info}) → FortisAesKey

Derives a ready-to-use FortisAesKey from the ECDH shared secret with publicKey.

deriveKey(FortisEcdhPublicKey publicKey, {Uint8List? salt, Uint8List? info}) → Uint8List

Derives raw key bytes from the ECDH shared secret with publicKey.

deriveSharedSecret(FortisEcdhPublicKey publicKey) → Uint8List

Computes the raw ECDH shared secret with the given publicKey.

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

toString() → String

A string representation of this object.

inherited

Operators

operator ==(Object other) → bool

The equality operator.

inherited

Static Methods

hkdf(Uint8List sharedSecret, {int keySize = 256, Uint8List? salt, Uint8List? info}) → Uint8List

Derives key bytes from an arbitrary shared secret using HKDF-SHA256 (RFC 5869).

hkdfDeriveAesKey(Uint8List sharedSecret, {int keySize = 256, Uint8List? salt, Uint8List? info}) → FortisAesKey

Derives a FortisAesKey from an arbitrary shared secret using HKDF-SHA256.