if err != nil {
			return nil, err
		}
		return newBoringPrivateKey(c, bk, key)
	}
	k := &PrivateKey{
		curve:      c,
		privateKey: append([]byte{}, key...),
	}
	return k, nil
}

func newBoringPrivateKey(c Curve, bk *boring.PrivateKeyECDH, privateKey []byte) (*PrivateKey, error) {
	k := &PrivateKey{
		curve:      c,
		boring:     bk,
		privateKey: append([]byte(nil), privateKey...),
	}
	return k, nil
}

// This file contains a math/big implementation of ECDSA that is only used for
// deprecated custom curves.

func generateLegacy(c elliptic.Curve, rand io.Reader) (*PrivateKey, error) {
	k, err := randFieldElement(c, rand)
	if err != nil {
		return nil, err
	}

	priv := new(PrivateKey)
	priv.PublicKey.Curve = c
	priv.D = k
	priv.PublicKey.X, priv.PublicKey.Y = c.ScalarBaseMult(k.Bytes())
	return priv, nil
}

func generateECDHEKey(rand io.Reader, curveID CurveID) (*ecdh.PrivateKey, error) {
	curve, ok := curveForCurveID(curveID)
	if !ok {
		return nil, errors.New("tls: internal error: unsupported curve")
	}

	return curve.GenerateKey(rand)
}

func curveForCurveID(id CurveID) (ecdh.Curve, bool) {
	switch id {
	case X25519:
		return ecdh.X25519(), true
	case CurveP256:

	}
	return out
}

// dhKEM implements the KEM specified in RFC 9180, Section 4.1.
type dhKEM struct {
	dh  ecdh.Curve
	kdf hkdfKDF

	suiteID []byte
	nSecret uint16
}

var SupportedKEMs = map[uint16]struct {
	curve   ecdh.Curve
	hash    crypto.Hash
	nSecret uint16
}{
	// RFC 9180 Section 7.1
	0x0020: {ecdh.X25519(), crypto.SHA256, 32},
}

	pkey := privKey.(*rsa.PrivateKey)
	return pkey.N.BitLen(), nil
}

// GetEllipticCurve returns the type of curve associated with the private key;
// if ECDSA is used, then only 384 and 256 (default) are returned; if non-ECDSA
// is used then an error is returned
func GetEllipticCurve(privKey *crypto.PrivateKey) (elliptic.Curve, error) {
	switch key := (*privKey).(type) {
	// this should agree with var SupportedECSignatureAlgorithms

			if err != nil {
				t.Fatal(err)
			}

			ephemeralPrivKey := mustDecodeHex(t, setup["skEm"])

			testingOnlyGenerateKey = func() (*ecdh.PrivateKey, error) {
				return SupportedKEMs[uint16(kemID)].curve.NewPrivateKey(ephemeralPrivKey)
			}
			t.Cleanup(func() { testingOnlyGenerateKey = nil })

			encap, context, err := SetupSender(
				uint16(kemID),
				uint16(kdfID),
				uint16(aeadID),
				pub,

	HasVX     bool // vector facility. Note: the runtime sets this when it processes auxv records.
	HasVXE    bool // vector-enhancements facility 1
	HasKDSA   bool // elliptic curve functions
	HasECDSA  bool // NIST curves
	HasEDDSA  bool // Edwards curves
	_         CacheLinePad
}

// CPU feature variables are accessed by assembly code in various packages.
//go:linkname X86