// Copyright 2019 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 pss
import (
"crypto/ecdsa"
"errors"
"fmt"
"sync"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/crypto"
"github.com/ethereum/go-ethereum/metrics"
"github.com/ethereum/go-ethereum/swarm/log"
whisper "github.com/ethereum/go-ethereum/whisper/whisperv6"
)
type KeyStore struct {
w *whisper.Whisper // key and encryption backend
mx sync.RWMutex
pubKeyPool map[string]map[Topic]*pssPeer // mapping of hex public keys to peer address by topic.
symKeyPool map[string]map[Topic]*pssPeer // mapping of symkeyids to peer address by topic.
symKeyDecryptCache []*string // fast lookup of symkeys recently used for decryption; last used is on top of stack
symKeyDecryptCacheCursor int // modular cursor pointing to last used, wraps on symKeyDecryptCache array
}
func loadKeyStore() *KeyStore {
return &KeyStore{
w: whisper.New(&whisper.DefaultConfig),
pubKeyPool: make(map[string]map[Topic]*pssPeer),
symKeyPool: make(map[string]map[Topic]*pssPeer),
symKeyDecryptCache: make([]*string, defaultSymKeyCacheCapacity),
}
}
func (ks *KeyStore) isSymKeyStored(key string) bool {
ks.mx.RLock()
defer ks.mx.RUnlock()
var ok bool
_, ok = ks.symKeyPool[key]
return ok
}
func (ks *KeyStore) isPubKeyStored(key string) bool {
ks.mx.RLock()
defer ks.mx.RUnlock()
var ok bool
_, ok = ks.pubKeyPool[key]
return ok
}
func (ks *KeyStore) getPeerSym(symkeyid string, topic Topic) (*pssPeer, bool) {
ks.mx.RLock()
defer ks.mx.RUnlock()
psp, ok := ks.symKeyPool[symkeyid][topic]
return psp, ok
}
func (ks *KeyStore) getPeerPub(pubkeyid string, topic Topic) (*pssPeer, bool) {
ks.mx.RLock()
defer ks.mx.RUnlock()
psp, ok := ks.pubKeyPool[pubkeyid][topic]
return psp, ok
}
// Links a peer ECDSA public key to a topic.
// This is required for asymmetric message exchange on the given topic.
// The value in `address` will be used as a routing hint for the public key / topic association.
func (ks *KeyStore) SetPeerPublicKey(pubkey *ecdsa.PublicKey, topic Topic, address PssAddress) error {
if err := validateAddress(address); err != nil {
return err
}
pubkeybytes := crypto.FromECDSAPub(pubkey)
if len(pubkeybytes) == 0 {
return fmt.Errorf("invalid public key: %v", pubkey)
}
pubkeyid := common.ToHex(pubkeybytes)
psp := &pssPeer{
address: address,
}
ks.mx.Lock()
if _, ok := ks.pubKeyPool[pubkeyid]; !ok {
ks.pubKeyPool[pubkeyid] = make(map[Topic]*pssPeer)
}
ks.pubKeyPool[pubkeyid][topic] = psp
ks.mx.Unlock()
log.Trace("added pubkey", "pubkeyid", pubkeyid, "topic", topic, "address", address)
return nil
}
// adds a symmetric key to the pss key pool, and optionally adds the key to the
// collection of keys used to attempt symmetric decryption of incoming messages
func (ks *KeyStore) addSymmetricKeyToPool(keyid string, topic Topic, address PssAddress, addtocache bool, protected bool) {
psp := &pssPeer{
address: address,
protected: protected,
}
ks.mx.Lock()
if _, ok := ks.symKeyPool[keyid]; !ok {
ks.symKeyPool[keyid] = make(map[Topic]*pssPeer)
}
ks.symKeyPool[keyid][topic] = psp
ks.mx.Unlock()
if addtocache {
ks.symKeyDecryptCacheCursor++
ks.symKeyDecryptCache[ks.symKeyDecryptCacheCursor%cap(ks.symKeyDecryptCache)] = &keyid
}
}
// Returns all recorded topic and address combination for a specific public key
func (ks *KeyStore) GetPublickeyPeers(keyid string) (topic []Topic, address []PssAddress, err error) {
ks.mx.RLock()
defer ks.mx.RUnlock()
for t, peer := range ks.pubKeyPool[keyid] {
topic = append(topic, t)
address = append(address, peer.address)
}
return topic, address, nil
}
func (ks *KeyStore) getPeerAddress(keyid string, topic Topic) (PssAddress, error) {
ks.mx.RLock()
defer ks.mx.RUnlock()
if peers, ok := ks.pubKeyPool[keyid]; ok {
if t, ok := peers[topic]; ok {
return t.address, nil
}
}
return nil, fmt.Errorf("peer with pubkey %s, topic %x not found", keyid, topic)
}
// Attempt to decrypt, validate and unpack a symmetrically encrypted message.
// If successful, returns the unpacked whisper ReceivedMessage struct
// encapsulating the decrypted message, and the whisper backend id
// of the symmetric key used to decrypt the message.
// It fails if decryption of the message fails or if the message is corrupted.
func (ks *KeyStore) processSym(envelope *whisper.Envelope) (*whisper.ReceivedMessage, string, PssAddress, error) {
metrics.GetOrRegisterCounter("pss.process.sym", nil).Inc(1)
for i := ks.symKeyDecryptCacheCursor; i > ks.symKeyDecryptCacheCursor-cap(ks.symKeyDecryptCache) && i > 0; i-- {
symkeyid := ks.symKeyDecryptCache[i%cap(ks.symKeyDecryptCache)]
symkey, err := ks.w.GetSymKey(*symkeyid)
if err != nil {
continue
}
recvmsg, err := envelope.OpenSymmetric(symkey)
if err != nil {
continue
}
if !recvmsg.ValidateAndParse() {
return nil, "", nil, errors.New("symmetrically encrypted message has invalid signature or is corrupt")
}
var from PssAddress
ks.mx.RLock()
if ks.symKeyPool[*symkeyid][Topic(envelope.Topic)] != nil {
from = ks.symKeyPool[*symkeyid][Topic(envelope.Topic)].address
}
ks.mx.RUnlock()
ks.symKeyDecryptCacheCursor++
ks.symKeyDecryptCache[ks.symKeyDecryptCacheCursor%cap(ks.symKeyDecryptCache)] = symkeyid
return recvmsg, *symkeyid, from, nil
}
return nil, "", nil, errors.New("could not decrypt message")
}
// Attempt to decrypt, validate and unpack an asymmetrically encrypted message.
// If successful, returns the unpacked whisper ReceivedMessage struct
// encapsulating the decrypted message, and the byte representation of
// the public key used to decrypt the message.
// It fails if decryption of message fails, or if the message is corrupted.
func (ks *Pss) processAsym(envelope *whisper.Envelope) (*whisper.ReceivedMessage, string, PssAddress, error) {
metrics.GetOrRegisterCounter("pss.process.asym", nil).Inc(1)
recvmsg, err := envelope.OpenAsymmetric(ks.privateKey)
if err != nil {
return nil, "", nil, fmt.Errorf("could not decrypt message: %s", err)
}
// check signature (if signed), strip padding
if !recvmsg.ValidateAndParse() {
return nil, "", nil, errors.New("invalid message")
}
pubkeyid := common.ToHex(crypto.FromECDSAPub(recvmsg.Src))
var from PssAddress
ks.mx.RLock()
if ks.pubKeyPool[pubkeyid][Topic(envelope.Topic)] != nil {
from = ks.pubKeyPool[pubkeyid][Topic(envelope.Topic)].address
}
ks.mx.RUnlock()
return recvmsg, pubkeyid, from, nil
}
// Symkey garbage collection
// a key is removed if:
// - it is not marked as protected
// - it is not in the incoming decryption cache
func (ks *Pss) cleanKeys() (count int) {
for keyid, peertopics := range ks.symKeyPool {
var expiredtopics []Topic
for topic, psp := range peertopics {
if psp.protected {
continue
}
var match bool
for i := ks.symKeyDecryptCacheCursor; i > ks.symKeyDecryptCacheCursor-cap(ks.symKeyDecryptCache) && i > 0; i-- {
cacheid := ks.symKeyDecryptCache[i%cap(ks.symKeyDecryptCache)]
if *cacheid == keyid {
match = true
}
}
if !match {
expiredtopics = append(expiredtopics, topic)
}
}
for _, topic := range expiredtopics {
ks.mx.Lock()
delete(ks.symKeyPool[keyid], topic)
log.Trace("symkey cleanup deletion", "symkeyid", keyid, "topic", topic, "val", ks.symKeyPool[keyid])
ks.mx.Unlock()
count++
}
}
return count
}
// Automatically generate a new symkey for a topic and address hint
func (ks *KeyStore) GenerateSymmetricKey(topic Topic, address PssAddress, addToCache bool) (string, error) {
keyid, err := ks.w.GenerateSymKey()
if err == nil {
ks.addSymmetricKeyToPool(keyid, topic, address, addToCache, false)
}
return keyid, err
}
// Returns a symmetric key byte sequence stored in the whisper backend by its unique id.
// Passes on the error value from the whisper backend.
func (ks *KeyStore) GetSymmetricKey(symkeyid string) ([]byte, error) {
return ks.w.GetSymKey(symkeyid)
}
// Links a peer symmetric key (arbitrary byte sequence) to a topic.
//
// This is required for symmetrically encrypted message exchange on the given topic.
//
// The key is stored in the whisper backend.
//
// If addtocache is set to true, the key will be added to the cache of keys
// used to attempt symmetric decryption of incoming messages.
//
// Returns a string id that can be used to retrieve the key bytes
// from the whisper backend (see pss.GetSymmetricKey())
func (ks *KeyStore) SetSymmetricKey(key []byte, topic Topic, address PssAddress, addtocache bool) (string, error) {
if err := validateAddress(address); err != nil {
return "", err
}
return ks.setSymmetricKey(key, topic, address, addtocache, true)
}
func (ks *KeyStore) setSymmetricKey(key []byte, topic Topic, address PssAddress, addtocache bool, protected bool) (string, error) {
keyid, err := ks.w.AddSymKeyDirect(key)
if err == nil {
ks.addSymmetricKeyToPool(keyid, topic, address, addtocache, protected)
}
return keyid, err
}
