path: root/p2p/enode/idscheme.go

// 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}
}