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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 enode
import (
"crypto/ecdsa"
"fmt"
"io"
"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/p2p/enr"
"github.com/ethereum/go-ethereum/rlp"
)
// List of known secure identity schemes.
var ValidSchemes = enr.SchemeMap{
"v4": V4ID{},
}
var ValidSchemesForTesting = enr.SchemeMap{
"v4": V4ID{},
"null": NullID{},
}
// v4ID is the "v4" identity scheme.
type V4ID struct{}
// SignV4 signs a record using the v4 scheme.
func SignV4(r *enr.Record, privkey *ecdsa.PrivateKey) error {
// Copy r to avoid modifying it if signing fails.
cpy := *r
cpy.Set(enr.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(V4ID{}, sig); err == nil {
*r = cpy
}
return err
}
func (V4ID) Verify(r *enr.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 enr.ErrInvalidSig
}
return nil
}
func (V4ID) NodeAddr(r *enr.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)
}
// Secp256k1 is the "secp256k1" key, which holds a public key.
type Secp256k1 ecdsa.PublicKey
func (v Secp256k1) ENRKey() string { return "secp256k1" }
// EncodeRLP implements rlp.Encoder.
func (v Secp256k1) EncodeRLP(w io.Writer) error {
return rlp.Encode(w, crypto.CompressPubkey((*ecdsa.PublicKey)(&v)))
}
// DecodeRLP implements rlp.Decoder.
func (v *Secp256k1) DecodeRLP(s *rlp.Stream) error {
buf, err := s.Bytes()
if err != nil {
return err
}
pk, err := crypto.DecompressPubkey(buf)
if err != nil {
return err
}
*v = (Secp256k1)(*pk)
return nil
}
// s256raw is an unparsed secp256k1 public key entry.
type s256raw []byte
func (s256raw) ENRKey() string { return "secp256k1" }
// v4CompatID is a weaker and insecure version of the "v4" scheme which only checks for the
// presence of a secp256k1 public key, but doesn't verify the signature.
type v4CompatID struct {
V4ID
}
func (v4CompatID) Verify(r *enr.Record, sig []byte) error {
var pubkey Secp256k1
return r.Load(&pubkey)
}
func signV4Compat(r *enr.Record, pubkey *ecdsa.PublicKey) {
r.Set((*Secp256k1)(pubkey))
if err := r.SetSig(v4CompatID{}, []byte{}); err != nil {
panic(err)
}
}
// NullID is the "null" ENR identity scheme. This scheme stores the node
// ID in the record without any signature.
type NullID struct{}
func (NullID) Verify(r *enr.Record, sig []byte) error {
return nil
}
func (NullID) NodeAddr(r *enr.Record) []byte {
var id ID
r.Load(enr.WithEntry("nulladdr", &id))
return id[:]
}
func SignNull(r *enr.Record, id ID) *Node {
r.Set(enr.ID("null"))
r.Set(enr.WithEntry("nulladdr", id))
if err := r.SetSig(NullID{}, []byte{}); err != nil {
panic(err)
}
return &Node{r: *r, id: id}
}
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