// SetupEncryptionKey calculates and internally sets encryption key `K` based on salt and info
//
// Only 32 bytes are used from HKDF-SHA512
func (p *SetupServerSession) SetupEncryptionKey(salt []byte, info []byte) error {
	hash, err := hkdf.Sha512(p.PrivateKey, salt, info)
	if err == nil {
		p.EncryptionKey = hash
	}

	return err
}
Exemple #2
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// SetupEncryptionKey generates an encryption key based on the shared key, salt and info.
func (s *VerifySession) SetupEncryptionKey(salt []byte, info []byte) error {
	hash, err := hkdf.Sha512(s.SharedKey[:], salt, info)
	if err == nil {
		s.EncryptionKey = hash
	}

	return err
}
// SetupEncryptionKey calculates encryption key `K` based on salt and info.
func (s *SetupClientSession) SetupEncryptionKey(salt []byte, info []byte) error {
	hash, err := hkdf.Sha512(s.PrivateKey, salt, info)
	if err == nil {
		s.EncryptionKey = hash
	}

	return err
}
Exemple #4
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// NewSecureClientSessionFromSharedKey returns a session from a shared secret key to simulate a HomeKit client.
// This is currently only used for testing.
func NewSecureClientSessionFromSharedKey(sharedKey [32]byte) (Cryptographer, error) {
	salt := []byte("Control-Salt")
	out := []byte("Control-Write-Encryption-Key")
	in := []byte("Control-Read-Encryption-Key")

	var s = new(secureSession)
	var err error
	s.encryptKey, err = hkdf.Sha512(sharedKey[:], salt, out)
	s.encryptCount = 0
	if err != nil {
		return nil, err
	}

	s.decryptKey, err = hkdf.Sha512(sharedKey[:], salt, in)
	s.decryptCount = 0

	return s, err
}
// Client -> Server
// - A: client public key
// - M1: proof
//
// Server -> client
// - M2: proof
// or
// - auth error
func (setup *SetupClientController) handlePairStepVerifyResponse(in util.Container) (util.Container, error) {
	serverProof := in.GetBytes(TagProof)
	fmt.Println("->     M2:", hex.EncodeToString(serverProof))

	if setup.session.IsServerProofValid(serverProof) == false {
		return nil, fmt.Errorf("M2 %s is invalid", hex.EncodeToString(serverProof))
	}

	err := setup.session.SetupEncryptionKey([]byte("Pair-Setup-Encrypt-Salt"), []byte("Pair-Setup-Encrypt-Info"))
	if err != nil {
		return nil, err
	}

	fmt.Println("        K:", hex.EncodeToString(setup.session.EncryptionKey[:]))

	// 2) Send username, LTPK, signature as encrypted message
	hash, err := hkdf.Sha512(setup.session.PrivateKey, []byte("Pair-Setup-Controller-Sign-Salt"), []byte("Pair-Setup-Controller-Sign-Info"))
	var material []byte
	material = append(material, hash[:]...)
	material = append(material, setup.client.Name()...)
	material = append(material, setup.client.PublicKey()...)

	signature, err := crypto.ED25519Signature(setup.client.PrivateKey(), material)
	if err != nil {
		return nil, err
	}

	encryptedOut := util.NewTLV8Container()
	encryptedOut.SetString(TagUsername, setup.client.Name())
	encryptedOut.SetBytes(TagPublicKey, []byte(setup.client.PublicKey()))
	encryptedOut.SetBytes(TagSignature, []byte(signature))

	encryptedBytes, tag, err := chacha20poly1305.EncryptAndSeal(setup.session.EncryptionKey[:], []byte("PS-Msg05"), encryptedOut.BytesBuffer().Bytes(), nil)
	if err != nil {
		return nil, err
	}

	out := util.NewTLV8Container()
	out.SetByte(TagPairingMethod, 0)
	out.SetByte(TagSequence, PairStepKeyExchangeRequest.Byte())
	out.SetBytes(TagEncryptedData, append(encryptedBytes, tag[:]...))

	fmt.Println("<-   Encrypted:", hex.EncodeToString(out.GetBytes(TagEncryptedData)))

	return out, nil
}
// Client -> Server
// - encrypted tlv8: entity ltpk, entity name and signature (of H, entity name, ltpk)
// - auth tag (mac)
//
// Server
// - Validate signature of encrpyted tlv8
// - Read and store entity ltpk and name
//
// Server -> Client
// - encrpyted tlv8: bridge ltpk, bridge name, signature (of hash, bridge name, ltpk)
func (setup *SetupServerController) handleKeyExchange(in util.Container) (util.Container, error) {
	out := util.NewTLV8Container()

	setup.step = PairStepKeyExchangeResponse

	out.SetByte(TagSequence, setup.step.Byte())

	data := in.GetBytes(TagEncryptedData)
	message := data[:(len(data) - 16)]
	var mac [16]byte
	copy(mac[:], data[len(message):]) // 16 byte (MAC)
	log.Debug.Println("->     Message:", hex.EncodeToString(message))
	log.Debug.Println("->     MAC:", hex.EncodeToString(mac[:]))

	decrypted, err := chacha20poly1305.DecryptAndVerify(setup.session.EncryptionKey[:], []byte("PS-Msg05"), message, mac, nil)

	if err != nil {
		setup.reset()
		log.Info.Panic(err)
		out.SetByte(TagErrCode, ErrCodeUnknown.Byte()) // return error 1
	} else {
		decryptedBuf := bytes.NewBuffer(decrypted)
		in, err := util.NewTLV8ContainerFromReader(decryptedBuf)
		if err != nil {
			return nil, err
		}

		username := in.GetString(TagUsername)
		clientltpk := in.GetBytes(TagPublicKey)
		signature := in.GetBytes(TagSignature)
		log.Debug.Println("->     Username:"******"->     ltpk:", hex.EncodeToString(clientltpk))
		log.Debug.Println("->     Signature:", hex.EncodeToString(signature))

		// Calculate hash `H`
		hash, _ := hkdf.Sha512(setup.session.PrivateKey, []byte("Pair-Setup-Controller-Sign-Salt"), []byte("Pair-Setup-Controller-Sign-Info"))
		var material []byte
		material = append(material, hash[:]...)
		material = append(material, []byte(username)...)
		material = append(material, clientltpk...)

		if crypto.ValidateED25519Signature(clientltpk, material, signature) == false {
			log.Debug.Println("ed25519 signature is invalid")
			setup.reset()
			out.SetByte(TagErrCode, ErrCodeAuthenticationFailed.Byte()) // return error 2
		} else {
			log.Debug.Println("ed25519 signature is valid")
			// Store entity ltpk and name
			entity := db.NewEntity(username, clientltpk, nil)
			setup.database.SaveEntity(entity)
			log.Debug.Printf("Stored ltpk '%s' for entity '%s'\n", hex.EncodeToString(clientltpk), username)

			ltpk := setup.device.PublicKey()
			ltsk := setup.device.PrivateKey()

			// Send username, ltpk, signature as encrypted message
			hash, err := hkdf.Sha512(setup.session.PrivateKey, []byte("Pair-Setup-Accessory-Sign-Salt"), []byte("Pair-Setup-Accessory-Sign-Info"))
			material = make([]byte, 0)
			material = append(material, hash[:]...)
			material = append(material, []byte(setup.session.Username)...)
			material = append(material, ltpk...)

			signature, err := crypto.ED25519Signature(ltsk, material)
			if err != nil {
				log.Info.Panic(err)
				return nil, err
			}

			tlvPairKeyExchange := util.NewTLV8Container()
			tlvPairKeyExchange.SetBytes(TagUsername, setup.session.Username)
			tlvPairKeyExchange.SetBytes(TagPublicKey, ltpk)
			tlvPairKeyExchange.SetBytes(TagSignature, []byte(signature))

			log.Debug.Println("<-     Username:"******"<-     ltpk:", hex.EncodeToString(tlvPairKeyExchange.GetBytes(TagPublicKey)))
			log.Debug.Println("<-     Signature:", hex.EncodeToString(tlvPairKeyExchange.GetBytes(TagSignature)))

			encrypted, mac, _ := chacha20poly1305.EncryptAndSeal(setup.session.EncryptionKey[:], []byte("PS-Msg06"), tlvPairKeyExchange.BytesBuffer().Bytes(), nil)
			out.SetByte(TagSequence, PairStepKeyExchangeRequest.Byte())
			out.SetBytes(TagEncryptedData, append(encrypted, mac[:]...))
		}
	}

	return out, nil
}