sign

type Dual[LPriv, LPub, RPriv, RPub any] struct {
	L Scheme[LPriv, LPub]
	R Scheme[RPriv, RPub]
}

type DualKey[L, R any] struct {
	L L
	R R
}

type Input512 = [64]byte

type PrivateKeyScheme[Private any] interface {
	MarshalPrivate(dst []byte, priv *Private)
	ParsePrivate(x []byte) (Private, error)
	PrivateKeySize() int
}

type PublicKeyScheme[Public any] interface {
	// MarshalPublic marshals a public key to binary data
	// MarshalPublic panics if dst is not >= PublicKeySize()
	MarshalPublic(dst []byte, pub *Public)
	// ParsePublic attempts to parse a public key from bytes
	ParsePublic([]byte) (Public, error)
	// PublicKeySize returns the size of a public key
	PublicKeySize() int
}

type Purpose[Private, Public, XOF any] struct {
	Scheme  Scheme512[Private, Public]
	Purpose string
	XOF     xof.Scheme[XOF]
}

type Scheme[Private, Public any] interface {
	// Generate creates a public and private key
	Generate(rng io.Reader) (pub Public, priv Private, err error)
	// DerivePublic derives the Public key which corresponds to the private key
	DerivePublic(*Private) Public

	// Sign uses priv to produce a signature for msg and writes it to dst.
	// dst must be at least SignatureSize
	Sign(dst []byte, priv *Private, msg []byte)
	// Verify checks if sig is a valid signature produced by pub for msg
	Verify(pub *Public, msg []byte, sig []byte) bool
	// SignatureSize returns the size of a public key
	SignatureSize() int

	PublicKeyScheme[Public]
	PrivateKeyScheme[Private]
}

type Scheme512[Private, Public any] interface {
	// Generate creates a public and private key
	Generate(rng io.Reader) (pub Public, priv Private, err error)
	// DerivePublic derives the Public key which corresponds to the private key
	DerivePublic(*Private) Public

	// Sign512 uses priv to produce a signature for msg and writes it to dst.
	// dst must be at least SignatureSize
	Sign512(dst []byte, priv *Private, input *Input512)
	// Verify512 checks if sig is a valid signature produced by pub for msg
	Verify512(pub *Public, input *Input512, sig []byte) bool
	// SignatureSize returns the size of a public key
	SignatureSize() int

	PublicKeyScheme[Public]
	PrivateKeyScheme[Private]
}