func NewCipher(key []byte) (cipher.Block, error) {
	k := len(key)
	switch k {
	default:
		return nil, KeySizeError(k)
	case 16, 24, 32:
		break
	}
	if boring.Enabled {
		return boring.NewAESCipher(key)
	}
	return newCipher(key)
}

// newCipherGeneric creates and returns a new cipher.Block
// implemented in pure Go.
func newCipherGeneric(key []byte) (cipher.Block, error) {

func SHA512([]byte) [64]byte { panic("boringcrypto: not available") }

func NewHMAC(h func() hash.Hash, key []byte) hash.Hash { panic("boringcrypto: not available") }

func NewAESCipher(key []byte) (cipher.Block, error) { panic("boringcrypto: not available") }
func NewGCMTLS(cipher.Block) (cipher.AEAD, error)   { panic("boringcrypto: not available") }

type PublicKeyECDSA struct{ _ int }

	NewCBCDecrypter(iv []byte) cipher.BlockMode
	NewCTR(iv []byte) cipher.Stream
	NewGCM(nonceSize, tagSize int) (cipher.AEAD, error)
}

var _ extraModes = (*aesCipher)(nil)

func NewAESCipher(key []byte) (cipher.Block, error) {
	c := &aesCipher{key: bytes.Clone(key)}
	// Note: 0 is success, contradicting the usual BoringCrypto convention.