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lnwallet: move latest SignDescriptor + serialization

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This commit is contained in:
Conner Fromknecht 2017-07-31 18:42:32 -07:00 committed by Olaoluwa Osuntokun
parent b7e426ecdc
commit 438c6b9621
3 changed files with 72 additions and 77 deletions
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60
lnwallet/interface.go
View File

@ -224,66 +224,6 @@ type BlockChainIO interface {
GetBlock(blockHash *chainhash.Hash) (*wire.MsgBlock, error)
}
// SignDescriptor houses the necessary information required to successfully sign
// a given output. This struct is used by the Signer interface in order to gain
// access to critical data needed to generate a valid signature.
type SignDescriptor struct {
// Pubkey is the public key to which the signature should be generated
// over. The Signer should then generate a signature with the private
// key corresponding to this public key.
PubKey *btcec.PublicKey
// SingleTweak is a scalar value that will be added to the private key
// corresponding to the above public key to obtain the private key to
// be used to sign this input. This value is typically derived via the
// following computation:
//
// * derivedKey = privkey + sha256(perCommitmentPoint || pubKey) mod N
//
// NOTE: If this value is nil, then the input can be signed using only
// the above public key. Either a SingleTweak should be set or a
// DoubleTweak, not both.
SingleTweak []byte
// DoubleTweak is a private key that will be used in combination with
// its corresponding private key to derive the private key that is to
// be used to sign the target input. Within the Lightning protocol,
// this value is typically the commitment secret from a previously
// revoked commitment transaction. This value is in combination with
// two hash values, and the original private key to derive the private
// key to be used when signing.
//
// * k = (privKey*sha256(pubKey || tweakPub) +
// tweakPriv*sha256(tweakPub || pubKey)) mod N
//
// NOTE: If this value is nil, then the input can be signed using only
// the above public key. Either a SingleTweak should be set or a
// DoubleTweak, not both.
DoubleTweak *btcec.PrivateKey
// WitnessScript is the full script required to properly redeem the
// output. This field will only be populated if a p2wsh or a p2sh
// output is being signed.
WitnessScript []byte
// Output is the target output which should be signed. The PkScript and
// Value fields within the output should be properly populated,
// otherwise an invalid signature may be generated.
Output *wire.TxOut
// HashType is the target sighash type that should be used when
// generating the final sighash, and signature.
HashType txscript.SigHashType
// SigHashes is the pre-computed sighash midstate to be used when
// generating the final sighash for signing.
SigHashes *txscript.TxSigHashes
// InputIndex is the target input within the transaction that should be
// signed.
InputIndex int
}
// Signer represents an abstract object capable of generating raw signatures as
// well as full complete input scripts given a valid SignDescriptor and
// transaction. This interface fully abstracts away signing paving the way for

85
lnwallet/signdescriptor.go
View File

@ -2,6 +2,7 @@ package lnwallet
import (
"encoding/binary"
"errors"
"io"
"github.com/lightningnetwork/lnd/lnwire"
@ -10,6 +11,12 @@ import (
"github.com/roasbeef/btcd/wire"
)
var (
// ErrTweakOverdose signals a SignDescriptor is invalid because both of its
// SingleTweak and DoubleTweak are non-nil.
ErrTweakOverdose = errors.New("sign descriptor should only have one tweak")
)
// SignDescriptor houses the necessary information required to successfully sign
// a given output. This struct is used by the Signer interface in order to gain
// access to critical data needed to generate a valid signature.
@ -19,14 +26,33 @@ type SignDescriptor struct {
// key corresponding to this public key.
PubKey *btcec.PublicKey
// PrivateTweak is a scalar value that should be added to the private
// key corresponding to the above public key to obtain the private key
// to be used to sign this input. This value is typically a leaf node
// from the revocation tree.
// SingleTweak is a scalar value that will be added to the private key
// corresponding to the above public key to obtain the private key to
// be used to sign this input. This value is typically derived via the
// following computation:
//
// * derivedKey = privkey + sha256(perCommitmentPoint || pubKey) mod N
//
// NOTE: If this value is nil, then the input can be signed using only
// the above public key.
PrivateTweak []byte
// the above public key. Either a SingleTweak should be set or a
// DoubleTweak, not both.
SingleTweak []byte
// DoubleTweak is a private key that will be used in combination with
// its corresponding private key to derive the private key that is to
// be used to sign the target input. Within the Lightning protocol,
// this value is typically the commitment secret from a previously
// revoked commitment transaction. This value is in combination with
// two hash values, and the original private key to derive the private
// key to be used when signing.
//
// * k = (privKey*sha256(pubKey || tweakPub) +
// tweakPriv*sha256(tweakPub || pubKey)) mod N
//
// NOTE: If this value is nil, then the input can be signed using only
// the above public key. Either a SingleTweak should be set or a
// DoubleTweak, not both.
DoubleTweak *btcec.PrivateKey
// WitnessScript is the full script required to properly redeem the
// output. This field will only be populated if a p2wsh or a p2sh
@ -62,7 +88,15 @@ func WriteSignDescriptor(w io.Writer, sd *SignDescriptor) error {
return err
}
if err := wire.WriteVarBytes(w, 0, sd.PrivateTweak); err != nil {
if err := wire.WriteVarBytes(w, 0, sd.SingleTweak); err != nil {
return err
}
var doubleTweakBytes []byte
if sd.DoubleTweak != nil {
doubleTweakBytes = sd.DoubleTweak.Serialize()
}
if err := wire.WriteVarBytes(w, 0, doubleTweakBytes); err != nil {
return err
}
@ -96,20 +130,41 @@ func ReadSignDescriptor(r io.Reader, sd *SignDescriptor) error {
return err
}
privateTweak, err := wire.ReadVarBytes(r, 0, 32, "privateTweak")
singleTweak, err := wire.ReadVarBytes(r, 0, 32, "singleTweak")
if err != nil {
return err
}
// Serializing a SignDescriptor with a nil-valued PrivateTweak results in
// deserializing a zero-length slice. Since a nil-valued PrivateTweak has
// special meaning and a zero-length slice for a PrivateTweak is invalid,
// Serializing a SignDescriptor with a nil-valued SingleTweak results in
// deserializing a zero-length slice. Since a nil-valued SingleTweak has
// special meaning and a zero-length slice for a SingleTweak is invalid,
// we can use the zero-length slice as the flag for a nil-valued
// PrivateTweak.
if len(privateTweak) == 0 {
sd.PrivateTweak = nil
// SingleTweak.
if len(singleTweak) == 0 {
sd.SingleTweak = nil
} else {
sd.PrivateTweak = privateTweak
sd.SingleTweak = singleTweak
}
doubleTweakBytes, err := wire.ReadVarBytes(r, 0, 32, "doubleTweak")
if err != nil {
return err
}
// Serializing a SignDescriptor with a nil-valued DoubleTweak results in
// deserializing a zero-length slice. Since a nil-valued DoubleTweak has
// special meaning and a zero-length slice for a DoubleTweak is invalid,
// we can use the zero-length slice as the flag for a nil-valued
// DoubleTweak.
if len(doubleTweakBytes) == 0 {
sd.DoubleTweak = nil
} else {
sd.DoubleTweak, _ = btcec.PrivKeyFromBytes(btcec.S256(), doubleTweakBytes)
}
// Only one tweak should ever be set, fail if both are present.
if sd.SingleTweak != nil && sd.DoubleTweak != nil {
return ErrTweakOverdose
}
witnessScript, err := wire.ReadVarBytes(r, 0, 100, "witnessScript")

4
lnwallet/signdescriptor_test.go
View File

@ -34,7 +34,7 @@ func TestSignDescriptorSerialization(t *testing.T) {
signDescriptors := []SignDescriptor{
{
PrivateTweak: []byte{
SingleTweak: []byte{
0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02,
0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02,
0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02,
@ -66,7 +66,7 @@ func TestSignDescriptorSerialization(t *testing.T) {
// Test serializing a SignDescriptor with a nil-valued PrivateTweak
{
PrivateTweak: nil,
SingleTweak: nil,
WitnessScript: []byte{
0x00, 0x14, 0xee, 0x91, 0x41, 0x7e, 0x85, 0x6c, 0xde,
0x10, 0xa2, 0x91, 0x1e, 0xdc, 0xbd, 0xbd, 0x69, 0xe2,