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

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package keys
import (
"bytes"
"crypto/ecdsa"
"crypto/elliptic"
"crypto/x509"
"encoding/hex"
"fmt"
"math/big"
"github.com/CityOfZion/neo-go/pkg/crypto/hash"
"github.com/CityOfZion/neo-go/pkg/encoding/address"
"github.com/CityOfZion/neo-go/pkg/io"
"github.com/CityOfZion/neo-go/pkg/vm/opcode"
"github.com/pkg/errors"
)
// 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
}
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// 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)
}
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// 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
}
// Bytes returns the byte array representation of the public key.
func (p *PublicKey) Bytes() []byte {
if p.IsInfinity() {
return []byte{0x00}
}
var (
x = p.X.Bytes()
paddedX = append(bytes.Repeat([]byte{0x00}, 32-len(x)), x...)
prefix = byte(0x03)
)
if p.Y.Bit(0) == 0 {
prefix = byte(0x02)
}
return append([]byte{prefix}, paddedX...)
}
// 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
}
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// decodeCompressedY performs decompression of Y coordinate for given X and Y's least significant bit.
func decodeCompressedY(x *big.Int, ylsb uint) (*big.Int, error) {
c := elliptic.P256()
cp := c.Params()
three := big.NewInt(3)
/* y**2 = x**3 + a*x + b % p */
xCubed := new(big.Int).Exp(x, three, cp.P)
threeX := new(big.Int).Mul(x, three)
threeX.Mod(threeX, cp.P)
ySquared := new(big.Int).Sub(xCubed, threeX)
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 {
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)
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r.ReadBytes(xbytes)
if r.Err != nil {
return
}
x = new(big.Int).SetBytes(xbytes)
ylsb := uint(prefix & 0x1)
y, err = decodeCompressedY(x, ylsb)
if err != nil {
r.Err = err
return
}
case 0x04:
xbytes := make([]byte, 32)
ybytes := make([]byte, 32)
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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
}
// Signature returns a NEO-specific hash of the key.
func (p *PublicKey) Signature() []byte {
sig := hash.Hash160(p.GetVerificationScript())
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return sig.BytesBE()
}
// Address returns a base58-encoded NEO-specific address based on the key hash.
func (p *PublicKey) Address() string {
sig := hash.Hash160(p.GetVerificationScript())
return address.Uint160ToString(sig)
}
// Verify returns true if the signature is valid and corresponds
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// 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)
}