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package secp256k1
import (
"bytes"
"crypto/sha256"
"crypto/subtle"
"fmt"
"io"
secp256k1 "github.com/tendermint/btcd/btcec"
amino "github.com/tendermint/go-amino"
"golang.org/x/crypto/ripemd160"
"github.com/tendermint/tendermint/crypto"
)
//-------------------------------------
const (
PrivKeyAminoRoute = "tendermint/PrivKeySecp256k1"
PubKeyAminoRoute = "tendermint/PubKeySecp256k1"
)
var cdc = amino.NewCodec()
func init() {
cdc.RegisterInterface((*crypto.PubKey)(nil), nil)
cdc.RegisterConcrete(PubKeySecp256k1{},
PubKeyAminoRoute, nil)
cdc.RegisterInterface((*crypto.PrivKey)(nil), nil)
cdc.RegisterConcrete(PrivKeySecp256k1{},
PrivKeyAminoRoute, nil)
}
//-------------------------------------
var _ crypto.PrivKey = PrivKeySecp256k1{}
// PrivKeySecp256k1 implements PrivKey.
type PrivKeySecp256k1 [32]byte
// Bytes marshalls the private key using amino encoding.
func (privKey PrivKeySecp256k1) Bytes() []byte {
return cdc.MustMarshalBinaryBare(privKey)
}
// Sign creates an ECDSA signature on curve Secp256k1, using SHA256 on the msg.
func (privKey PrivKeySecp256k1) Sign(msg []byte) ([]byte, error) {
priv, _ := secp256k1.PrivKeyFromBytes(secp256k1.S256(), privKey[:])
sig, err := priv.Sign(crypto.Sha256(msg))
if err != nil {
return nil, err
}
return sig.Serialize(), nil
}
// PubKey performs the point-scalar multiplication from the privKey on the
// generator point to get the pubkey.
func (privKey PrivKeySecp256k1) PubKey() crypto.PubKey {
_, pubkeyObject := secp256k1.PrivKeyFromBytes(secp256k1.S256(), privKey[:])
var pubkeyBytes PubKeySecp256k1
copy(pubkeyBytes[:], pubkeyObject.SerializeCompressed())
return pubkeyBytes
}
// Equals - you probably don't need to use this.
// Runs in constant time based on length of the keys.
func (privKey PrivKeySecp256k1) Equals(other crypto.PrivKey) bool {
if otherSecp, ok := other.(PrivKeySecp256k1); ok {
return subtle.ConstantTimeCompare(privKey[:], otherSecp[:]) == 1
}
return false
}
// GenPrivKey generates a new ECDSA private key on curve secp256k1 private key.
// It uses OS randomness in conjunction with the current global random seed
// in tendermint/libs/common to generate the private key.
func GenPrivKey() PrivKeySecp256k1 {
return genPrivKey(crypto.CReader())
}
// genPrivKey generates a new secp256k1 private key using the provided reader.
func genPrivKey(rand io.Reader) PrivKeySecp256k1 {
privKeyBytes := [32]byte{}
_, err := io.ReadFull(rand, privKeyBytes[:])
if err != nil {
panic(err)
}
// crypto.CRandBytes is guaranteed to be 32 bytes long, so it can be
// casted to PrivKeySecp256k1.
return PrivKeySecp256k1(privKeyBytes)
}
// GenPrivKeySecp256k1 hashes the secret with SHA2, and uses
// that 32 byte output to create the private key.
// NOTE: secret should be the output of a KDF like bcrypt,
// if it's derived from user input.
func GenPrivKeySecp256k1(secret []byte) PrivKeySecp256k1 {
privKey32 := sha256.Sum256(secret)
// sha256.Sum256() is guaranteed to be 32 bytes long, so it can be
// casted to PrivKeySecp256k1.
return PrivKeySecp256k1(privKey32)
}
//-------------------------------------
var _ crypto.PubKey = PubKeySecp256k1{}
// PubKeySecp256k1Size is comprised of 32 bytes for one field element
// (the x-coordinate), plus one byte for the parity of the y-coordinate.
const PubKeySecp256k1Size = 33
// PubKeySecp256k1 implements crypto.PubKey.
// It is the compressed form of the pubkey. The first byte depends is a 0x02 byte
// if the y-coordinate is the lexicographically largest of the two associated with
// the x-coordinate. Otherwise the first byte is a 0x03.
// This prefix is followed with the x-coordinate.
type PubKeySecp256k1 [PubKeySecp256k1Size]byte
// Address returns a Bitcoin style addresses: RIPEMD160(SHA256(pubkey))
func (pubKey PubKeySecp256k1) Address() crypto.Address {
hasherSHA256 := sha256.New()
hasherSHA256.Write(pubKey[:]) // does not error
sha := hasherSHA256.Sum(nil)
hasherRIPEMD160 := ripemd160.New()
hasherRIPEMD160.Write(sha) // does not error
return crypto.Address(hasherRIPEMD160.Sum(nil))
}
// Bytes returns the pubkey marshalled with amino encoding.
func (pubKey PubKeySecp256k1) Bytes() []byte {
bz, err := cdc.MarshalBinaryBare(pubKey)
if err != nil {
panic(err)
}
return bz
}
func (pubKey PubKeySecp256k1) VerifyBytes(msg []byte, sig []byte) bool {
pub, err := secp256k1.ParsePubKey(pubKey[:], secp256k1.S256())
if err != nil {
return false
}
parsedSig, err := secp256k1.ParseSignature(sig[:], secp256k1.S256())
if err != nil {
return false
}
// Underlying library ensures that this signature is in canonical form, to
// prevent Secp256k1 malleability from altering the sign of the s term.
return parsedSig.Verify(crypto.Sha256(msg), pub)
}
func (pubKey PubKeySecp256k1) String() string {
return fmt.Sprintf("PubKeySecp256k1{%X}", pubKey[:])
}
func (pubKey PubKeySecp256k1) Equals(other crypto.PubKey) bool {
if otherSecp, ok := other.(PubKeySecp256k1); ok {
return bytes.Equal(pubKey[:], otherSecp[:])
}
return false
}