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// Copyright 2018 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package enr
import (
"crypto/ecdsa"
"fmt"
"sync"
"github.com/ethereum/go-ethereum/common/math"
"github.com/ethereum/go-ethereum/crypto"
"github.com/ethereum/go-ethereum/crypto/sha3"
"github.com/ethereum/go-ethereum/rlp"
)
// Registry of known identity schemes.
var schemes sync.Map
// An IdentityScheme is capable of verifying record signatures and
// deriving node addresses.
type IdentityScheme interface {
Verify(r *Record, sig []byte) error
NodeAddr(r *Record) []byte
}
// RegisterIdentityScheme adds an identity scheme to the global registry.
func RegisterIdentityScheme(name string, scheme IdentityScheme) {
if _, loaded := schemes.LoadOrStore(name, scheme); loaded {
panic("identity scheme " + name + " already registered")
}
}
// FindIdentityScheme resolves name to an identity scheme in the global registry.
func FindIdentityScheme(name string) IdentityScheme {
s, ok := schemes.Load(name)
if !ok {
return nil
}
return s.(IdentityScheme)
}
// v4ID is the "v4" identity scheme.
type v4ID struct{}
func init() {
RegisterIdentityScheme("v4", v4ID{})
}
// SignV4 signs a record using the v4 scheme.
func SignV4(r *Record, privkey *ecdsa.PrivateKey) error {
// Copy r to avoid modifying it if signing fails.
cpy := *r
cpy.Set(ID("v4"))
cpy.Set(Secp256k1(privkey.PublicKey))
h := sha3.NewKeccak256()
rlp.Encode(h, cpy.AppendElements(nil))
sig, err := crypto.Sign(h.Sum(nil), privkey)
if err != nil {
return err
}
sig = sig[:len(sig)-1] // remove v
if err = cpy.SetSig("v4", sig); err == nil {
*r = cpy
}
return err
}
// s256raw is an unparsed secp256k1 public key entry.
type s256raw []byte
func (s256raw) ENRKey() string { return "secp256k1" }
func (v4ID) Verify(r *Record, sig []byte) error {
var entry s256raw
if err := r.Load(&entry); err != nil {
return err
} else if len(entry) != 33 {
return fmt.Errorf("invalid public key")
}
h := sha3.NewKeccak256()
rlp.Encode(h, r.AppendElements(nil))
if !crypto.VerifySignature(entry, h.Sum(nil), sig) {
return errInvalidSig
}
return nil
}
func (v4ID) NodeAddr(r *Record) []byte {
var pubkey Secp256k1
err := r.Load(&pubkey)
if err != nil {
return nil
}
buf := make([]byte, 64)
math.ReadBits(pubkey.X, buf[:32])
math.ReadBits(pubkey.Y, buf[32:])
return crypto.Keccak256(buf)
}