func TestEncodeDecodeWIF(t *testing.T) {
	priv1, _ := btcec.PrivKeyFromBytes(btcec.S256(), []byte{
		0x0c, 0x28, 0xfc, 0xa3, 0x86, 0xc7, 0xa2, 0x27,
		0x60, 0x0b, 0x2f, 0xe5, 0x0b, 0x7c, 0xae, 0x11,
		0xec, 0x86, 0xd3, 0xbf, 0x1f, 0xbe, 0x47, 0x1b,
		0xe8, 0x98, 0x27, 0xe1, 0x9d, 0x72, 0xaa, 0x1d})

	priv2, _ := btcec.PrivKeyFromBytes(btcec.S256(), []byte{
		0xdd, 0xa3, 0x5a, 0x14, 0x88, 0xfb, 0x97, 0xb6,
		0xeb, 0x3f, 0xe6, 0xe9, 0xef, 0x2a, 0x25, 0x81,
		0x4e, 0x39, 0x6f, 0xb5, 0xdc, 0x29, 0x5f, 0xe9,
		0x94, 0xb9, 0x67, 0x89, 0xb2, 0x1a, 0x03, 0x98})

	wif1, err := NewWIF(priv1, &chaincfg.MainNetParams, false)
	if err != nil {
		t.Fatal(err)
	}
	wif2, err := NewWIF(priv2, &chaincfg.TestNet3Params, true)
	if err != nil {
		t.Fatal(err)
	}

	tests := []struct {
		wif     *WIF
		encoded string
	}{
		{
			wif1,
			"5HueCGU8rMjxEXxiPuD5BDku4MkFqeZyd4dZ1jvhTVqvbTLvyTJ",
		},
		{
			wif2,
			"cV1Y7ARUr9Yx7BR55nTdnR7ZXNJphZtCCMBTEZBJe1hXt2kB684q",
		},
	}

	for _, test := range tests {
		// Test that encoding the WIF structure matches the expected string.
		s := test.wif.String()
		if s != test.encoded {
			t.Errorf("TestEncodeDecodePrivateKey failed: want '%s', got '%s'",
				test.encoded, s)
			continue
		}

		// Test that decoding the expected string results in the original WIF
		// structure.
		w, err := DecodeWIF(test.encoded)
		if err != nil {
			t.Error(err)
			continue
		}
		if got := w.String(); got != test.encoded {
			t.Errorf("NewWIF failed: want '%v', got '%v'", test.wif, got)
		}
	}
}

func GenPrivKeySecp256k1() PrivKeySecp256k1 {
	privKeyBytes := [32]byte{}
	copy(privKeyBytes[:], CRandBytes(32))
	priv, _ := secp256k1.PrivKeyFromBytes(secp256k1.S256(), privKeyBytes[:])
	copy(privKeyBytes[:], priv.Serialize())
	return PrivKeySecp256k1(privKeyBytes)
}

// This example demonstrates signing a message with a secp256k1 private key that
// is first parsed form raw bytes and serializing the generated signature.
func Example_signMessage() {
	// Decode a hex-encoded private key.
	pkBytes, err := hex.DecodeString("22a47fa09a223f2aa079edf85a7c2d4f87" +
		"20ee63e502ee2869afab7de234b80c")
	if err != nil {
		fmt.Println(err)
		return
	}
	privKey, pubKey := btcec.PrivKeyFromBytes(btcec.S256(), pkBytes)

	// Sign a message using the private key.
	message := "test message"
	messageHash := wire.DoubleSha256([]byte(message))
	signature, err := privKey.Sign(messageHash)
	if err != nil {
		fmt.Println(err)
		return
	}

	// Serialize and display the signature.
	//
	// NOTE: This is commented out for the example since the signature
	// produced uses random numbers and therefore will always be different.
	//fmt.Printf("Serialized Signature: %x\n", signature.Serialize())

	// Verify the signature for the message using the public key.
	verified := signature.Verify(messageHash, pubKey)
	fmt.Printf("Signature Verified? %v\n", verified)

	// Output:
	// Signature Verified? true
}

// This example demonstrates decrypting a message using a private key that is
// first parsed from raw bytes.
func Example_decryptMessage() {
	// Decode the hex-encoded private key.
	pkBytes, err := hex.DecodeString("a11b0a4e1a132305652ee7a8eb7848f6ad" +
		"5ea381e3ce20a2c086a2e388230811")
	if err != nil {
		fmt.Println(err)
		return
	}

	privKey, _ := btcec.PrivKeyFromBytes(btcec.S256(), pkBytes)

	ciphertext, err := hex.DecodeString("35f644fbfb208bc71e57684c3c8b437402ca" +
		"002047a2f1b38aa1a8f1d5121778378414f708fe13ebf7b4a7bb74407288c1958969" +
		"00207cf4ac6057406e40f79961c973309a892732ae7a74ee96cd89823913b8b8d650" +
		"a44166dc61ea1c419d47077b748a9c06b8d57af72deb2819d98a9d503efc59fc8307" +
		"d14174f8b83354fac3ff56075162")

	// Try decrypting the message.
	plaintext, err := btcec.Decrypt(privKey, ciphertext)
	if err != nil {
		fmt.Println(err)
		return
	}

	fmt.Println(string(plaintext))

	// Output:
	// test message
}

// PrivKey returns the private key for the address.  It can fail if the address
// manager is watching-only or locked, or the address does not have any keys.
//
// This is part of the ManagedPubKeyAddress interface implementation.
func (a *managedAddress) PrivKey() (*btcec.PrivateKey, error) {
	// No private keys are available for a watching-only address manager.
	if a.manager.watchingOnly {
		return nil, managerError(ErrWatchingOnly, errWatchingOnly, nil)
	}

	a.manager.mtx.Lock()
	defer a.manager.mtx.Unlock()

	// Account manager must be unlocked to decrypt the private key.
	if a.manager.locked {
		return nil, managerError(ErrLocked, errLocked, nil)
	}

	// Decrypt the key as needed.  Also, make sure it's a copy since the
	// private key stored in memory can be cleared at any time.  Otherwise
	// the returned private key could be invalidated from under the caller.
	privKeyCopy, err := a.unlock(a.manager.cryptoKeyPriv)
	if err != nil {
		return nil, err
	}

	privKey, _ := btcec.PrivKeyFromBytes(btcec.S256(), privKeyCopy)
	zero.Bytes(privKeyCopy)
	return privKey, nil
}

// This example demonstrates signing a message with a secp256k1 private key that
// is first parsed form raw bytes and serializing the generated signature.
func Example_signMessage() {
	// Decode a hex-encoded private key.
	pkBytes, err := hex.DecodeString("22a47fa09a223f2aa079edf85a7c2d4f87" +
		"20ee63e502ee2869afab7de234b80c")
	if err != nil {
		fmt.Println(err)
		return
	}
	privKey, pubKey := btcec.PrivKeyFromBytes(btcec.S256(), pkBytes)

	// Sign a message using the private key.
	message := "test message"
	messageHash := wire.DoubleSha256([]byte(message))
	signature, err := privKey.Sign(messageHash)
	if err != nil {
		fmt.Println(err)
		return
	}

	// Serialize and display the signature.
	fmt.Printf("Serialized Signature: %x\n", signature.Serialize())

	// Verify the signature for the message using the public key.
	verified := signature.Verify(messageHash, pubKey)
	fmt.Printf("Signature Verified? %v\n", verified)

	// Output:
	// Serialized Signature: 304402201008e236fa8cd0f25df4482dddbb622e8a8b26ef0ba731719458de3ccd93805b022032f8ebe514ba5f672466eba334639282616bb3c2f0ab09998037513d1f9e3d6d
	// Signature Verified? true
}

// NOTE: secret should be the output of a KDF like bcrypt,
// if it's derived from user input.
func GenPrivKeySecp256k1FromSecret(secret []byte) PrivKeySecp256k1 {
	privKey32 := Sha256(secret) // Not Ripemd160 because we want 32 bytes.
	priv, _ := secp256k1.PrivKeyFromBytes(secp256k1.S256(), privKey32)
	privKeyBytes := [32]byte{}
	copy(privKeyBytes[:], priv.Serialize())
	return PrivKeySecp256k1(privKeyBytes)
}

//Returns a btec.Private key object if provided a correct secp256k1 encoded pem.
func ExtractKeyFromPem(pm string) *btcec.PrivateKey {
	byta := []byte(pm)
	blck, _ := pem.Decode(byta)
	var ecp ecPrivateKey
	asn1.Unmarshal(blck.Bytes, &ecp)
	priv, _ := btcec.PrivKeyFromBytes(btcec.S256(), ecp.PrivateKey)
	return priv
}

func Sign(private, data []byte) ([]byte, error) {
	privkey, _ := btcec.PrivKeyFromBytes(btcec.S256(), private)
	sig, err := privkey.Sign(data)
	if err != nil {
		return nil, err
	}
	return sig.Serialize(), nil
}

// Returns DER encoded signature from input hash
func signECDSA(privateKey, hash []byte) ([]byte, error) {
	priv, _ := btcec.PrivKeyFromBytes(btcec.S256(), privateKey)
	sig, err := priv.Sign(hash)
	if err != nil {
		return nil, err
	}
	return sig.Serialize(), nil
}

// ECPrivKey converts the extended key to a btcec private key and returns it.
// As you might imagine this is only possible if the extended key is a private
// extended key (as determined by the IsPrivate function).  The ErrNotPrivExtKey
// error will be returned if this function is called on a public extended key.
func (k *ExtendedKey) ECPrivKey() (*btcec.PrivateKey, error) {
	if !k.isPrivate {
		return nil, ErrNotPrivExtKey
	}

	privKey, _ := btcec.PrivKeyFromBytes(btcec.S256(), k.key)
	return privKey, nil
}

func (privKey PrivKeySecp256k1) Sign(msg []byte) Signature {
	priv__, _ := secp256k1.PrivKeyFromBytes(secp256k1.S256(), privKey[:])
	sig__, err := priv__.Sign(Sha256(msg))
	if err != nil {
		PanicSanity(err)
	}
	return SignatureSecp256k1(sig__.Serialize())
}

//Generates child public key from parent private key
func (ek *ExtendedKey) CKDpub(index uint32) (*ExtendedPublicKey, error) {
	childPrivateKey, _ := ek.CKDpriv(index)
	chaincode := childPrivateKey.Chaincode

	_, publicKey := btcec.PrivKeyFromBytes(btcec.S256(), childPrivateKey.PrivateKey)
	childExtendedPublicKey := NewExtendedPublicKey(publicKey.X.Bytes(), publicKey.Y.Bytes(), childPrivateKey.Depth, childPrivateKey.ParentFingerPrint, index, chaincode, publicKey.SerializeCompressed())

	return childExtendedPublicKey, nil
}

func newKey(seed []byte) *btcec.PrivateKey {
	inc := big.NewInt(0).SetBytes(seed)
	inc.Lsh(inc, 32)
	for key := big.NewInt(0); ; inc.Add(inc, one) {
		key.SetBytes(Sha512Half(inc.Bytes()))
		if key.Cmp(zero) > 0 && key.Cmp(order) < 0 {
			privKey, _ := btcec.PrivKeyFromBytes(btcec.S256(), key.Bytes())
			return privKey
		}
	}
}

//Extended keys can be identified by the Hash160 (RIPEMD160 after SHA256)
//of the serialized ECSDA public key K, ignoring the chain code
//The first 32 bits of the identifier are called the key fingerprint.
func (ek *ExtendedKey) GetFingerPrint() []byte {
	_, publicKey := btcec.PrivKeyFromBytes(btcec.S256(), ek.PrivateKey)
	sha_256 := sha256.New()
	sha_256.Write(publicKey.SerializeCompressed())
	sha := sha_256.Sum(nil)
	ripemd := ripemd160.New()
	ripemd.Write(sha)
	final := ripemd.Sum(nil)

	return final[:4]
}

// GenerateKeyPairDeterministic computes the public/private keypair for the
// given entropy.
func GenerateKeyPairDeterministic(entropy *Entropy) (*SecretKey, *PublicKey) {
	// Create key pair deterministically from the given entropy
	sk_s, pk_s := btcec.PrivKeyFromBytes(S256, entropy[:])

	// Serialize the key pair
	sk := newSecretKeyInt(sk_s.D)
	pk := newPublicKeyCoords(pk_s.X, pk_s.Y)

	sk_s.D.SetUint64(0)

	return sk, pk
}

//Calculate I = HMAC-SHA512(Key = "Bitcoin seed", Data = S)
func GenerateMasterKey(seed []byte) (*ExtendedKey, *ExtendedPublicKey, error) {
	seedString := []byte("Bitcoin seed")
	hmac512 := hmac.New(sha512.New, seedString)
	hmac512.Write(seed)
	raw := hmac512.Sum(nil)
	ParentFingerPrint := []byte{0x00, 0x00, 0x00, 0x00}
	var depth byte
	depth = 0x00
	var childNumber uint32
	childNumber = 0
	_, publicKey := btcec.PrivKeyFromBytes(btcec.S256(), raw[:32])
	masterPrivateKey := NewExtendedKey(depth, ParentFingerPrint, childNumber, raw[32:], raw[:32])
	masterPublicKey := NewExtendedPublicKey(publicKey.X.Bytes(), publicKey.Y.Bytes(), depth, ParentFingerPrint, childNumber, raw[32:], publicKey.SerializeCompressed())

	return masterPrivateKey, masterPublicKey, nil
}

func TestPrivKeys(t *testing.T) {
	tests := []struct {
		name string
		key  []byte
	}{
		{
			name: "check curve",
			key: []byte{
				0xea, 0xf0, 0x2c, 0xa3, 0x48, 0xc5, 0x24, 0xe6,
				0x39, 0x26, 0x55, 0xba, 0x4d, 0x29, 0x60, 0x3c,
				0xd1, 0xa7, 0x34, 0x7d, 0x9d, 0x65, 0xcf, 0xe9,
				0x3c, 0xe1, 0xeb, 0xff, 0xdc, 0xa2, 0x26, 0x94,
			},
		},
	}

	for _, test := range tests {
		priv, pub := btcec.PrivKeyFromBytes(btcec.S256(), test.key)

		_, err := btcec.ParsePubKey(
			pub.SerializeUncompressed(), btcec.S256())
		if err != nil {
			t.Errorf("%s privkey: %v", test.name, err)
			continue
		}

		hash := []byte{0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9}
		sig, err := priv.Sign(hash)
		if err != nil {
			t.Errorf("%s could not sign: %v", test.name, err)
			continue
		}

		if !sig.Verify(hash, pub) {
			t.Errorf("%s could not verify: %v", test.name, err)
			continue
		}

		serializedKey := priv.Serialize()
		if !bytes.Equal(serializedKey, test.key) {
			t.Errorf("%s unexpected serialized bytes - got: %x, "+
				"want: %x", test.name, serializedKey, test.key)
		}
	}
}

// This example demonstrates encrypting a message for a public key that is first
// parsed from raw bytes, then decrypting it using the corresponding private key.
func Example_encryptMessage() {
	// Decode the hex-encoded pubkey of the recipient.
	pubKeyBytes, err := hex.DecodeString("04115c42e757b2efb7671c578530ec191a1" +
		"359381e6a71127a9d37c486fd30dae57e76dc58f693bd7e7010358ce6b165e483a29" +
		"21010db67ac11b1b51b651953d2") // uncompressed pubkey
	if err != nil {
		fmt.Println(err)
		return
	}
	pubKey, err := btcec.ParsePubKey(pubKeyBytes, btcec.S256())
	if err != nil {
		fmt.Println(err)
		return
	}

	// Encrypt a message decryptable by the private key corresponding to pubKey
	message := "test message"
	ciphertext, err := btcec.Encrypt(pubKey, []byte(message))
	if err != nil {
		fmt.Println(err)
		return
	}

	// Decode the hex-encoded private key.
	pkBytes, err := hex.DecodeString("a11b0a4e1a132305652ee7a8eb7848f6ad" +
		"5ea381e3ce20a2c086a2e388230811")
	if err != nil {
		fmt.Println(err)
		return
	}
	// note that we already have corresponding pubKey
	privKey, _ := btcec.PrivKeyFromBytes(btcec.S256(), pkBytes)

	// Try decrypting and verify if it's the same message.
	plaintext, err := btcec.Decrypt(privKey, ciphertext)
	if err != nil {
		fmt.Println(err)
		return
	}

	fmt.Println(string(plaintext))

	// Output:
	// test message
}

// newBobNode generates a test "ln node" to interact with Alice (us). For the
// funding transaction, bob has a single output totaling 7BTC. For our basic
// test, he'll fund the channel with 5BTC, leaving 2BTC to the change output.
// TODO(roasbeef): proper handling of change etc.
func newBobNode() (*bobNode, error) {
	// First, parse Bob's priv key in order to obtain a key he'll use for the
	// multi-sig funding transaction.
	privKey, pubKey := btcec.PrivKeyFromBytes(btcec.S256(), bobsPrivKey)

	// Next, generate an output redeemable by bob.
	bobAddr, err := btcutil.NewAddressPubKey(privKey.PubKey().SerializeCompressed(),
		ActiveNetParams)
	if err != nil {
		return nil, err
	}
	bobAddrScript, err := txscript.PayToAddrScript(bobAddr.AddressPubKeyHash())
	if err != nil {
		return nil, err
	}
	prevOut := wire.NewOutPoint(&wire.ShaHash{}, ^uint32(0))
	// TODO(roasbeef): When the chain rpc is hooked in, assert bob's output
	// actually exists and it unspent in the chain.
	bobTxIn := wire.NewTxIn(prevOut, nil)

	// Using bobs priv key above, create a change address he can spend.
	bobChangeOutput := wire.NewTxOut(2*1e8, bobAddrScript)

	// Bob's initial revocation hash is just his private key with the first
	// byte changed...
	var revocation [20]byte
	copy(revocation[:], bobsPrivKey)
	revocation[0] = 0xff

	// His ID is just as creative...
	var id [wire.HashSize]byte
	id[0] = 0xff

	return &bobNode{
		id:               id,
		privKey:          privKey,
		channelKey:       pubKey,
		deliveryAddress:  bobAddr,
		revocation:       revocation,
		delay:            5,
		availableOutputs: []*wire.TxIn{bobTxIn},
		changeOutputs:    []*wire.TxOut{bobChangeOutput},
	}, nil
}