neoneo-go/pkg/crypto/keys/publickey.go

428 lines
11 KiB
Go

package keys
import (
"crypto/ecdsa"
"crypto/elliptic"
"crypto/x509"
"encoding/hex"
"encoding/json"
"fmt"
"math/big"
"github.com/btcsuite/btcd/btcec"
"github.com/nspcc-dev/neo-go/pkg/crypto/hash"
"github.com/nspcc-dev/neo-go/pkg/encoding/address"
"github.com/nspcc-dev/neo-go/pkg/io"
"github.com/nspcc-dev/neo-go/pkg/util"
"github.com/nspcc-dev/neo-go/pkg/vm/opcode"
"github.com/pkg/errors"
)
// coordLen is the number of bytes in serialized X or Y coordinate.
const coordLen = 32
// PublicKeys is a list of public keys.
type PublicKeys []*PublicKey
func (keys PublicKeys) Len() int { return len(keys) }
func (keys PublicKeys) Swap(i, j int) { keys[i], keys[j] = keys[j], keys[i] }
func (keys PublicKeys) Less(i, j int) bool {
return keys[i].Cmp(keys[j]) == -1
}
// DecodeBytes decodes a PublicKeys from the given slice of bytes.
func (keys *PublicKeys) DecodeBytes(data []byte) error {
b := io.NewBinReaderFromBuf(data)
b.ReadArray(keys)
return b.Err
}
// Contains checks whether passed param contained in PublicKeys.
func (keys PublicKeys) Contains(pKey *PublicKey) bool {
for _, key := range keys {
if key.Equal(pKey) {
return true
}
}
return false
}
// Unique returns set of public keys.
func (keys PublicKeys) Unique() PublicKeys {
unique := PublicKeys{}
for _, publicKey := range keys {
if !unique.Contains(publicKey) {
unique = append(unique, publicKey)
}
}
return unique
}
// PublicKey represents a public key and provides a high level
// API around the X/Y point.
type PublicKey struct {
X *big.Int
Y *big.Int
}
// Equal returns true in case public keys are equal.
func (p *PublicKey) Equal(key *PublicKey) bool {
return p.X.Cmp(key.X) == 0 && p.Y.Cmp(key.Y) == 0
}
// Cmp compares two keys.
func (p *PublicKey) Cmp(key *PublicKey) int {
xCmp := p.X.Cmp(key.X)
if xCmp != 0 {
return xCmp
}
return p.Y.Cmp(key.Y)
}
// NewPublicKeyFromString returns a public key created from the
// given hex string.
func NewPublicKeyFromString(s string) (*PublicKey, error) {
b, err := hex.DecodeString(s)
if err != nil {
return nil, err
}
pubKey := new(PublicKey)
r := io.NewBinReaderFromBuf(b)
pubKey.DecodeBinary(r)
if r.Err != nil {
return nil, r.Err
}
return pubKey, nil
}
// getBytes serializes X and Y using compressed or uncompressed format.
func (p *PublicKey) getBytes(compressed bool) []byte {
if p.IsInfinity() {
return []byte{0x00}
}
var resLen = 1 + coordLen
if !compressed {
resLen += coordLen
}
var res = make([]byte, resLen)
var prefix byte
xBytes := p.X.Bytes()
copy(res[1+coordLen-len(xBytes):], xBytes)
if compressed {
if p.Y.Bit(0) == 0 {
prefix = 0x02
} else {
prefix = 0x03
}
} else {
prefix = 0x04
yBytes := p.Y.Bytes()
copy(res[1+coordLen+coordLen-len(yBytes):], yBytes)
}
res[0] = prefix
return res
}
// Bytes returns byte array representation of the public key in compressed
// form (33 bytes with 0x02 or 0x03 prefix, except infinity which is always 0).
func (p *PublicKey) Bytes() []byte {
return p.getBytes(true)
}
// UncompressedBytes returns byte array representation of the public key in
// uncompressed form (65 bytes with 0x04 prefix, except infinity which is
// always 0).
func (p *PublicKey) UncompressedBytes() []byte {
return p.getBytes(false)
}
// NewPublicKeyFromASN1 returns a NEO PublicKey from the ASN.1 serialized key.
func NewPublicKeyFromASN1(data []byte) (*PublicKey, error) {
var (
err error
pubkey interface{}
)
if pubkey, err = x509.ParsePKIXPublicKey(data); err != nil {
return nil, err
}
pk, ok := pubkey.(*ecdsa.PublicKey)
if !ok {
return nil, errors.New("given bytes aren't ECDSA public key")
}
key := PublicKey{
X: pk.X,
Y: pk.Y,
}
return &key, nil
}
// decodeCompressedY performs decompression of Y coordinate for given X and Y's least significant bit.
// We use here a short-form Weierstrass curve (https://www.hyperelliptic.org/EFD/g1p/auto-shortw.html)
// y² = x³ + ax + b. Two types of elliptic curves are supported:
// 1. Secp256k1 (Koblitz curve): y² = x³ + b,
// 2. Secp256r1 (Random curve): y² = x³ - 3x + b.
// To decode compressed curve point we perform the following operation: y = sqrt(x³ + ax + b mod p)
// where `p` denotes the order of the underlying curve field
func decodeCompressedY(x *big.Int, ylsb uint, curve elliptic.Curve) (*big.Int, error) {
var a *big.Int
switch curve.(type) {
case *btcec.KoblitzCurve:
a = big.NewInt(0)
default:
a = big.NewInt(3)
}
cp := curve.Params()
xCubed := new(big.Int).Exp(x, big.NewInt(3), cp.P)
aX := new(big.Int).Mul(x, a)
aX.Mod(aX, cp.P)
ySquared := new(big.Int).Sub(xCubed, aX)
ySquared.Add(ySquared, cp.B)
ySquared.Mod(ySquared, cp.P)
y := new(big.Int).ModSqrt(ySquared, cp.P)
if y == nil {
return nil, errors.New("error computing Y for compressed point")
}
if y.Bit(0) != ylsb {
y.Neg(y)
y.Mod(y, cp.P)
}
return y, nil
}
// DecodeBytes decodes a PublicKey from the given slice of bytes.
func (p *PublicKey) DecodeBytes(data []byte) error {
l := len(data)
if !((l == 1 && data[0] == 0) ||
(l == 33 && (data[0] == 0x02 || data[0] == 0x03)) ||
(l == 65 && data[0] == 0x04)) {
return errors.New("invalid key size/prefix")
}
b := io.NewBinReaderFromBuf(data)
p.DecodeBinary(b)
return b.Err
}
// DecodeBinary decodes a PublicKey from the given BinReader.
func (p *PublicKey) DecodeBinary(r *io.BinReader) {
var prefix uint8
var x, y *big.Int
var err error
prefix = uint8(r.ReadB())
if r.Err != nil {
return
}
p256 := elliptic.P256()
p256Params := p256.Params()
// Infinity
switch prefix {
case 0x00:
// noop, initialized to nil
return
case 0x02, 0x03:
// Compressed public keys
xbytes := make([]byte, 32)
r.ReadBytes(xbytes)
if r.Err != nil {
return
}
x = new(big.Int).SetBytes(xbytes)
ylsb := uint(prefix & 0x1)
y, err = decodeCompressedY(x, ylsb, p256)
if err != nil {
r.Err = err
return
}
case 0x04:
xbytes := make([]byte, 32)
ybytes := make([]byte, 32)
r.ReadBytes(xbytes)
r.ReadBytes(ybytes)
if r.Err != nil {
return
}
x = new(big.Int).SetBytes(xbytes)
y = new(big.Int).SetBytes(ybytes)
if !p256.IsOnCurve(x, y) {
r.Err = errors.New("encoded point is not on the P256 curve")
return
}
default:
r.Err = errors.Errorf("invalid prefix %d", prefix)
return
}
if x.Cmp(p256Params.P) >= 0 || y.Cmp(p256Params.P) >= 0 {
r.Err = errors.New("enccoded point is not correct (X or Y is bigger than P")
return
}
p.X, p.Y = x, y
}
// EncodeBinary encodes a PublicKey to the given BinWriter.
func (p *PublicKey) EncodeBinary(w *io.BinWriter) {
w.WriteBytes(p.Bytes())
}
// GetVerificationScript returns NEO VM bytecode with CHECKSIG command for the
// public key.
func (p *PublicKey) GetVerificationScript() []byte {
b := p.Bytes()
b = append([]byte{byte(opcode.PUSHBYTES33)}, b...)
b = append(b, byte(opcode.CHECKSIG))
return b
}
// GetScriptHash returns a Hash160 of verification script for the key.
func (p *PublicKey) GetScriptHash() util.Uint160 {
return hash.Hash160(p.GetVerificationScript())
}
// Address returns a base58-encoded NEO-specific address based on the key hash.
func (p *PublicKey) Address() string {
return address.Uint160ToString(p.GetScriptHash())
}
// Verify returns true if the signature is valid and corresponds
// to the hash and public key.
func (p *PublicKey) Verify(signature []byte, hash []byte) bool {
publicKey := &ecdsa.PublicKey{}
publicKey.Curve = elliptic.P256()
publicKey.X = p.X
publicKey.Y = p.Y
if p.X == nil || p.Y == nil {
return false
}
rBytes := new(big.Int).SetBytes(signature[0:32])
sBytes := new(big.Int).SetBytes(signature[32:64])
return ecdsa.Verify(publicKey, hash, rBytes, sBytes)
}
// IsInfinity checks if the key is infinite (null, basically).
func (p *PublicKey) IsInfinity() bool {
return p.X == nil && p.Y == nil
}
// String implements the Stringer interface.
func (p *PublicKey) String() string {
if p.IsInfinity() {
return "00"
}
bx := hex.EncodeToString(p.X.Bytes())
by := hex.EncodeToString(p.Y.Bytes())
return fmt.Sprintf("%s%s", bx, by)
}
// MarshalJSON implements the json.Marshaler interface.
func (p PublicKey) MarshalJSON() ([]byte, error) {
return json.Marshal(hex.EncodeToString(p.Bytes()))
}
// UnmarshalJSON implements json.Unmarshaler interface.
func (p *PublicKey) UnmarshalJSON(data []byte) error {
l := len(data)
if l < 2 || data[0] != '"' || data[l-1] != '"' {
return errors.New("wrong format")
}
bytes := make([]byte, hex.DecodedLen(l-2))
_, err := hex.Decode(bytes, data[1:l-1])
if err != nil {
return err
}
err = p.DecodeBytes(bytes)
if err != nil {
return err
}
return nil
}
// KeyRecover recovers public key from the given signature (r, s) on the given message hash using given elliptic curve.
// Algorithm source: SEC 1 Ver 2.0, section 4.1.6, pages 47-48 (https://www.secg.org/sec1-v2.pdf).
// Flag isEven denotes Y's least significant bit in decompression algorithm.
func KeyRecover(curve elliptic.Curve, r, s *big.Int, messageHash []byte, isEven bool) (PublicKey, error) {
var (
res PublicKey
err error
)
if r.Cmp(big.NewInt(1)) == -1 || s.Cmp(big.NewInt(1)) == -1 {
return res, errors.New("invalid signature")
}
params := curve.Params()
// Calculate h = (Q + 1 + 2 * Sqrt(Q)) / N
// num := new(big.Int).Add(new(big.Int).Add(params.P, big.NewInt(1)), new(big.Int).Mul(big.NewInt(2), new(big.Int).Sqrt(params.P)))
// h := new(big.Int).Div(num, params.N)
// We are skipping this step for secp256k1 and secp256r1 because we know cofactor of these curves (h=1)
// (see section 2.4 of http://www.secg.org/sec2-v2.pdf)
h := 1
for i := 0; i <= h; i++ {
// Step 1.1: x = (n * i) + r
Rx := new(big.Int).Mul(params.N, big.NewInt(int64(i)))
Rx.Add(Rx, r)
if Rx.Cmp(params.P) == 1 {
break
}
// Steps 1.2 and 1.3: get point R (Ry)
var R *big.Int
if isEven {
R, err = decodeCompressedY(Rx, 0, curve)
} else {
R, err = decodeCompressedY(Rx, 1, curve)
}
if err != nil {
return res, err
}
// Step 1.4: check n*R is point at infinity
nRx, nR := curve.ScalarMult(Rx, R, params.N.Bytes())
if nRx.Sign() != 0 || nR.Sign() != 0 {
continue
}
// Step 1.5: compute e
e := hashToInt(messageHash, curve)
// Step 1.6: Q = r^-1 (sR-eG)
invr := new(big.Int).ModInverse(r, params.N)
// First term.
invrS := new(big.Int).Mul(invr, s)
invrS.Mod(invrS, params.N)
sRx, sR := curve.ScalarMult(Rx, R, invrS.Bytes())
// Second term.
e.Neg(e)
e.Mod(e, params.N)
e.Mul(e, invr)
e.Mod(e, params.N)
minuseGx, minuseGy := curve.ScalarBaseMult(e.Bytes())
Qx, Qy := curve.Add(sRx, sR, minuseGx, minuseGy)
res.X = Qx
res.Y = Qy
}
return res, nil
}
// copied from crypto/ecdsa
func hashToInt(hash []byte, c elliptic.Curve) *big.Int {
orderBits := c.Params().N.BitLen()
orderBytes := (orderBits + 7) / 8
if len(hash) > orderBytes {
hash = hash[:orderBytes]
}
ret := new(big.Int).SetBytes(hash)
excess := len(hash)*8 - orderBits
if excess > 0 {
ret.Rsh(ret, uint(excess))
}
return ret
}