// newHandshakeState returns a new instance of the handshake state initialized
// with the prologue and protocol name. If this is the respodner's handshake
// state, then the remotePub can be nil.
func newHandshakeState(initiator bool, prologue []byte,
localPub *btcec.PrivateKey, remotePub *btcec.PublicKey) handshakeState {
h := handshakeState{
initiator: initiator,
localStatic: localPub,
remoteStatic: remotePub,
}
// Set the current chainking key and handshake digest to the hash of
// the protocol name, and additionally mix in the prologue. If either
// sides disagree about the prologue or protocol name, then the
// handshake will fail.
h.InitializeSymmetric([]byte(protocolName))
h.mixHash(prologue)
// In Noise_XK, then initiator should know the responder's static
// public key, therefore we include the responder's static key in the
// handshake digest. If the initiator gets this value wrong, then the
// handshake will fail.
if initiator {
h.mixHash(remotePub.SerializeCompressed())
} else {
h.mixHash(localPub.PubKey().SerializeCompressed())
}
return h
}
// FetchOpenChannel returns all stored currently active/open channels
// associated with the target nodeID. In the case that no active channels are
// known to have been created with this node, then a zero-length slice is
// returned.
func (d *DB) FetchOpenChannels(nodeID *btcec.PublicKey) ([]*OpenChannel, error) {
var channels []*OpenChannel
err := d.store.View(func(tx *bolt.Tx) error {
// Get the bucket dedicated to storing the meta-data for open
// channels.
openChanBucket := tx.Bucket(openChannelBucket)
if openChanBucket == nil {
return nil
}
// Within this top level bucket, fetch the bucket dedicated to storing
// open channel data specific to the remote node.
pub := nodeID.SerializeCompressed()
nodeChanBucket := openChanBucket.Bucket(pub)
if nodeChanBucket == nil {
return nil
}
// Finally, we both of the necessary buckets retrieved, fetch
// all the active channels related to this node.
nodeChannels, err := d.fetchNodeChannels(openChanBucket,
nodeChanBucket)
if err != nil {
return err
}
channels = nodeChannels
return nil
})
return channels, err
}
// commitScriptToSelf constructs the public key script for the output on the
// commitment transaction paying to the "owner" of said commitment transaction.
// If the other party learns of the pre-image to the revocation hash, then they
// can claim all the settled funds in the channel, plus the unsettled funds.
//
// Possible Input Scripts:
// REVOKE: <sig> 1
// SENDRSWEEP: <sig> 0
//
// Output Script:
// OP_IF
// <revokeKey> OP_CHECKSIG
// OP_ELSE
// <timeKey> OP_CHECKSIGVERIFY
// <numRelativeBlocks> OP_CHECKSEQUENCEVERIFY
// OP_ENDIF
func commitScriptToSelf(csvTimeout uint32, selfKey, revokeKey *btcec.PublicKey) ([]byte, error) {
// This script is spendable under two conditions: either the 'csvTimeout'
// has passed and we can redeem our funds, or they can produce a valid
// signature with the revocation public key. The revocation public key
// will *only* be known to the other party if we have divulged the
// revocation hash, allowing them to homomorphically derive the proper
// private key which corresponds to the revoke public key.
builder := txscript.NewScriptBuilder()
builder.AddOp(txscript.OP_IF)
// If a valid signature using the revocation key is presented, then
// allow an immediate spend provided the proper signature.
builder.AddData(revokeKey.SerializeCompressed())
builder.AddOp(txscript.OP_CHECKSIG)
builder.AddOp(txscript.OP_ELSE)
// Otherwise, we can re-claim our funds after a CSV delay of
// 'csvTimeout' timeout blocks, and a valid signature.
builder.AddData(selfKey.SerializeCompressed())
builder.AddOp(txscript.OP_CHECKSIGVERIFY)
builder.AddInt64(int64(csvTimeout))
builder.AddOp(OP_CHECKSEQUENCEVERIFY)
builder.AddOp(txscript.OP_ENDIF)
return builder.Script()
}
// commitScriptUnencumbered constructs the public key script on the commitment
// transaction paying to the "other" party. The constructed output is a normal
// p2wkh output spendable immediately, requiring no contestation period.
func commitScriptUnencumbered(key *btcec.PublicKey) ([]byte, error) {
// This script goes to the "other" party, and it spendable immediately.
builder := txscript.NewScriptBuilder()
builder.AddOp(txscript.OP_0)
builder.AddData(btcutil.Hash160(key.SerializeCompressed()))
return builder.Script()
}
// computeBlindingFactor for the next hop given the ephemeral pubKey and
// sharedSecret for this hop. The blinding factor is computed as the
// sha-256(pubkey || sharedSecret).
func computeBlindingFactor(hopPubKey *btcec.PublicKey, hopSharedSecret []byte) [sha256.Size]byte {
sha := sha256.New()
sha.Write(hopPubKey.SerializeCompressed())
sha.Write(hopSharedSecret)
var hash [sha256.Size]byte
copy(hash[:], sha.Sum(nil))
return hash
}
// UnregisterLink requets the htlcSwitch to unregiser the new active link. An
// unregistered link will no longer be considered a candidate to forward
// HTLC's.
func (h *htlcSwitch) UnregisterLink(remotePub *btcec.PublicKey, chanPoint *wire.OutPoint) {
done := make(chan struct{}, 1)
rawPub := remotePub.SerializeCompressed()
h.linkControl <- &unregisterLinkMsg{
chanInterface: fastsha256.Sum256(rawPub),
chanPoint: chanPoint,
remoteID: rawPub,
done: done,
}
<-done
}
// fetchPrivKey attempts to retrieve the raw private key coresponding to the
// passed public key.
// TODO(roasbeef): alternatively can extract all the data pushes within the
// script, then attempt to match keys one by one
func (b *BtcWallet) fetchPrivKey(pub *btcec.PublicKey) (*btcec.PrivateKey, error) {
hash160 := btcutil.Hash160(pub.SerializeCompressed())
addr, err := btcutil.NewAddressWitnessPubKeyHash(hash160, b.netParams)
if err != nil {
return nil, err
}
walletddr, err := b.wallet.Manager.Address(addr)
if err != nil {
return nil, err
}
return walletddr.(waddrmgr.ManagedPubKeyAddress).PrivKey()
}
// deriveElkremRoot derives an elkrem root unique to a channel given the
// private key for our public key in the 2-of-2 multi-sig, and the remote
// node's multi-sig public key. The root is derived using the HKDF[1][2]
// instantiated with sha-256. The secret data used is our multi-sig private
// key, with the salt being the remote node's public key.
//
// [1]: https://eprint.iacr.org/2010/264.pdf
// [2]: https://tools.ietf.org/html/rfc5869
func deriveElkremRoot(elkremDerivationRoot *btcec.PrivateKey,
localMultiSigKey *btcec.PublicKey,
remoteMultiSigKey *btcec.PublicKey) wire.ShaHash {
secret := elkremDerivationRoot.Serialize()
salt := localMultiSigKey.SerializeCompressed()
info := remoteMultiSigKey.SerializeCompressed()
rootReader := hkdf.New(sha256.New, secret, salt, info)
// It's safe to ignore the error her as we know for sure that we won't
// be draining the HKDF past its available entropy horizon.
// TODO(roasbeef): revisit...
var elkremRoot wire.ShaHash
rootReader.Read(elkremRoot[:])
return elkremRoot
}
// FetchLinkNode attempts to lookup the data for a LinkNode based on a target
// identity public key. If a particular LinkNode for the passed identity public
// key cannot be found, then ErrNodeNotFound if returned.
func (db *DB) FetchLinkNode(identity *btcec.PublicKey) (*LinkNode, error) {
var (
node *LinkNode
err error
)
err = db.store.View(func(tx *bolt.Tx) error {
// First fetch the bucket for storing node meta-data, bailing
// out early if it hasn't been created yet.
nodeMetaBucket := tx.Bucket(nodeInfoBucket)
if nodeInfoBucket == nil {
return fmt.Errorf("node bucket not created")
}
// If a link node for that particular public key cannot be
// located, then exit early with a ErrNodeNotFound.
pubKey := identity.SerializeCompressed()
nodeBytes := nodeMetaBucket.Get(pubKey)
if nodeBytes == nil {
return ErrNodeNotFound
}
// Finally, decode an allocate a fresh LinkNode object to be
// returned to the caller.
nodeReader := bytes.NewReader(nodeBytes)
node, err = deserializeLinkNode(nodeReader)
if err != nil {
return err
}
return nil
})
if err != nil {
return nil, err
}
return node, nil
}
// newManagedAddressWithoutPrivKey returns a new managed address based on the
// passed account, public key, and whether or not the public key should be
// compressed.
func newManagedAddressWithoutPrivKey(m *Manager, account uint32, pubKey *btcec.PublicKey,
compressed bool, addrType addressType) (*managedAddress, error) {
// Create a pay-to-pubkey-hash address from the public key.
var pubKeyHash []byte
if compressed {
pubKeyHash = btcutil.Hash160(pubKey.SerializeCompressed())
} else {
pubKeyHash = btcutil.Hash160(pubKey.SerializeUncompressed())
}
var address btcutil.Address
var err error
switch addrType {
// TODO(roasbeef): only use these types in the db?
case adtChainNestedWitness:
// For this address type we'l generate an address which is
// backwards compatible to Bitcoin nodes running 0.6.0 onwards, but
// allows us to take advantage of segwit's scripting improvments,
// and malleability fixes.
// First, we'll generate a normal p2wkh address from the pubkey hash.
witAddr, err := btcutil.NewAddressWitnessPubKeyHash(pubKeyHash, m.chainParams)
if err != nil {
return nil, err
}
// Next we'll generate the witness program which can be used as a
// pkScript to pay to this generated address.
witnessProgram, err := txscript.PayToAddrScript(witAddr)
if err != nil {
return nil, err
}
// Finally, we'll use the witness program itself as the pre-image
// to a p2sh address. In order to spend, we first use the
// witnessProgram as the sigScript, then present the proper
// <sig, pubkey> pair as the witness.
address, err = btcutil.NewAddressScriptHash(witnessProgram, m.chainParams)
if err != nil {
return nil, err
}
case adtImport:
// TODO(roasbeef): truly proper?
fallthrough
case adtChain:
address, err = btcutil.NewAddressPubKeyHash(pubKeyHash, m.chainParams)
if err != nil {
return nil, err
}
case adtChainWitness:
address, err = btcutil.NewAddressWitnessPubKeyHash(pubKeyHash, m.chainParams)
if err != nil {
return nil, err
}
}
return &managedAddress{
manager: m,
address: address,
account: account,
imported: false,
internal: false,
addrType: addrType,
compressed: compressed,
pubKey: pubKey,
privKeyEncrypted: nil,
privKeyCT: nil,
}, nil
}
// receiverHTLCScript constructs the public key script for an incoming HTLC
// output payment for the receiver's version of the commitment transaction:
//
// Possible Input Scripts:
// RECVR: <sig> <preimage> 1
// REVOK: <sig> <preimage> 1 0
// SENDR: <sig> 0 0
//
// OP_IF
// //Receiver
// OP_SIZE 32 OP_EQUALVERIFY
// OP_SHA256
// <payment hash> OP_EQUALVERIFY
// <relative blockheight> OP_CHECKSEQUENCEVERIFY OP_DROP
// <receiver key> OP_CHECKSIG
// OP_ELSE
// //Sender
// OP_IF
// //Revocation
// OP_SHA256
// <revoke hash> OP_EQUALVERIFY
// OP_ELSE
// //Refund
// <absolute blockehight> OP_CHECKLOCKTIMEVERIFY OP_DROP
// OP_ENDIF
// <sender key> OP_CHECKSIG
// OP_ENDIF
// TODO(roasbeef): go back to revocation keys in the HTLC outputs?
// * also could combine pre-image with their key?
func receiverHTLCScript(absoluteTimeout, relativeTimeout uint32, senderKey,
receiverKey *btcec.PublicKey, revokeHash, paymentHash []byte) ([]byte, error) {
builder := txscript.NewScriptBuilder()
// The receiver of the script will place a 1 as the first item of the
// witness stack forcing Script execution to enter the "if" clause of
// the main body of the script.
builder.AddOp(txscript.OP_IF)
// In this clause, the receiver can redeem the HTLC after a relative timeout.
// This added delay gives the sender (at this time) an opportunity to
// re-claim the pending HTLC in the event that the receiver
// (at this time) broadcasts this old commitment transaction after it
// has been revoked. Additionally, we require that the pre-image is
// exactly 32-bytes in order to avoid undesirable redemption
// asymmerties in the multi-hop scenario.
builder.AddOp(txscript.OP_SIZE)
builder.AddInt64(32)
builder.AddOp(txscript.OP_EQUALVERIFY)
builder.AddOp(txscript.OP_SHA256)
builder.AddData(paymentHash)
builder.AddOp(txscript.OP_EQUALVERIFY)
builder.AddInt64(int64(relativeTimeout))
builder.AddOp(OP_CHECKSEQUENCEVERIFY)
builder.AddOp(txscript.OP_DROP)
builder.AddData(receiverKey.SerializeCompressed())
builder.AddOp(txscript.OP_CHECKSIG)
// Otherwise, the sender will place a 0 as the first item of the
// witness stack forcing exeuction to enter the "else" clause of the
// main body of the script.
builder.AddOp(txscript.OP_ELSE)
// The sender will place a 1 as the second item of the witness stack
// in the scenario that the receiver broadcasts an invalidated
// commitment transaction, allowing the sender to sweep all the
// receiver's funds.
builder.AddOp(txscript.OP_IF)
builder.AddOp(txscript.OP_SHA256)
builder.AddData(revokeHash)
builder.AddOp(txscript.OP_EQUALVERIFY)
// If not, then the sender needs to wait for the HTLC timeout. This
// clause may be executed if the receiver fails to present the r-value
// in time. This prevents the pending funds from being locked up
// indefinately.
// The sender will place a 0 as the second item of the witness stack if
// they wish to sweep the HTLC after an absolute refund timeout. This
// time out clause prevents the pending funds from being locked up
// indefinately.
builder.AddOp(txscript.OP_ELSE)
builder.AddInt64(int64(absoluteTimeout))
builder.AddOp(txscript.OP_CHECKLOCKTIMEVERIFY)
builder.AddOp(txscript.OP_DROP)
builder.AddOp(txscript.OP_ENDIF)
// In either case, we also require a valid signature with the sender's
// commitment private key.
builder.AddData(senderKey.SerializeCompressed())
builder.AddOp(txscript.OP_CHECKSIG)
builder.AddOp(txscript.OP_ENDIF)
return builder.Script()
}
// senderHTLCScript constructs the public key script for an outgoing HTLC
// output payment for the sender's version of the commitment transaction:
//
// Possible Input Scripts:
// SENDR: <sig> 0
// RECVR: <sig> <preimage> 0 1
// REVOK: <sig <preimage> 1 1
// * receiver revoke
//
// OP_IF
// //Receiver
// OP_IF
// //Revoke
// <revocation hash>
// OP_ELSE
// //Receive
// OP_SIZE 32 OP_EQUALVERIFY
// <payment hash>
// OP_ENDIF
// OP_SWAP
// OP_SHA256 OP_EQUALVERIFY
// <recv key> OP_CHECKSIG
// OP_ELSE
// //Sender
// <absolute blockheight> OP_CHECKLOCKTIMEVERIFY
// <relative blockheight> OP_CHECKSEQUENCEVERIFY
// OP_2DROP
// <sendr key> OP_CHECKSIG
// OP_ENDIF
func senderHTLCScript(absoluteTimeout, relativeTimeout uint32, senderKey,
receiverKey *btcec.PublicKey, revokeHash, paymentHash []byte) ([]byte, error) {
builder := txscript.NewScriptBuilder()
// The receiver of the HTLC places a 1 as the first item in the witness
// stack, forcing Script execution to enter the "if" clause within the
// main body of the script.
builder.AddOp(txscript.OP_IF)
// The receiver will place a 1 as the second item of the witness stack
// in the case the sender broadcasts a revoked commitment transaction.
// Executing this branch allows the receiver to claim the sender's
// funds as a result of their contract violation.
builder.AddOp(txscript.OP_IF)
builder.AddData(revokeHash)
// Alternatively, the receiver can place a 0 as the second item of the
// witness stack if they wish to claim the HTLC with the proper
// pre-image as normal. In order to prevent an over-sized pre-image
// attack (which can create undesirable redemption asymmerties), we
// strongly require that all HTLC pre-images are exactly 32 bytes.
builder.AddOp(txscript.OP_ELSE)
builder.AddOp(txscript.OP_SIZE)
builder.AddInt64(32)
builder.AddOp(txscript.OP_EQUALVERIFY)
builder.AddData(paymentHash)
builder.AddOp(txscript.OP_ENDIF)
builder.AddOp(txscript.OP_SWAP)
builder.AddOp(txscript.OP_SHA256)
builder.AddOp(txscript.OP_EQUALVERIFY)
// In either case, we require a valid signature by the receiver.
builder.AddData(receiverKey.SerializeCompressed())
builder.AddOp(txscript.OP_CHECKSIG)
// Otherwise, the sender of the HTLC will place a 0 as the first item
// of the witness stack in order to sweep the funds back after the HTLC
// times out.
builder.AddOp(txscript.OP_ELSE)
// In this case, the sender will need to wait for an absolute HTLC
// timeout, then afterwards a relative timeout before we claim re-claim
// the unsettled funds. This delay gives the other party a chance to
// present the pre-image to the revocation hash in the event that the
// sender (at this time) broadcasts this commitment transaction after
// it has been revoked.
builder.AddInt64(int64(absoluteTimeout))
builder.AddOp(txscript.OP_CHECKLOCKTIMEVERIFY)
builder.AddInt64(int64(relativeTimeout))
builder.AddOp(OP_CHECKSEQUENCEVERIFY)
builder.AddOp(txscript.OP_2DROP)
builder.AddData(senderKey.SerializeCompressed())
builder.AddOp(txscript.OP_CHECKSIG)
builder.AddOp(txscript.OP_ENDIF)
return builder.Script()
}