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