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promise.go
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promise.go
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/* Mysterium network payment library.
*
* Copyright (C) 2020 BlockDev AG
*
* This program 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.
* This program 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 General Public License for more details.
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
package crypto
import (
"encoding/binary"
"encoding/hex"
"fmt"
"math/big"
"github.com/ethereum/go-ethereum/accounts"
"github.com/ethereum/go-ethereum/accounts/keystore"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/common/math"
"github.com/ethereum/go-ethereum/crypto"
"github.com/pkg/errors"
)
// Promise is payment promise object
type Promise struct {
ChannelID []byte
ChainID int64
Amount *big.Int
Fee *big.Int
Hashlock []byte
R []byte
Signature []byte
}
// CreatePromise creates and signs new payment promise
func CreatePromise(channelID string, chainID int64, amount *big.Int, fee *big.Int, hashlock string, ks hashSigner, signer common.Address) (*Promise, error) {
if hasHexPrefix(channelID) {
channelID = channelID[2:]
}
if hasHexPrefix(hashlock) {
hashlock = hashlock[2:]
}
if !isHex(channelID) || !isHex(hashlock) {
return nil, errors.New("channelID and hashlock have to be proper hex strings")
}
chID, err := hex.DecodeString(channelID)
if err != nil {
return nil, errors.Wrap(err, "Problem in decoding channelID")
}
hl, err := hex.DecodeString(hashlock)
if err != nil {
return nil, errors.Wrap(err, "Problem in decoding hashlock")
}
promise := Promise{
ChannelID: chID,
Amount: amount,
Fee: fee,
Hashlock: hl,
ChainID: chainID,
}
signature, err := promise.CreateSignature(ks, signer)
if err != nil {
return nil, err
}
if err := ReformatSignatureVForBC(signature); err != nil {
return nil, fmt.Errorf("failed to reformat signature: %w", err)
}
promise.Signature = signature
return &promise, nil
}
// NewPromise will create new promise,
// signature can be empty and be created later using `Sign()` method.
func NewPromise(chainID int64, channelID string, amount, fee *big.Int, preimage string, signature string) (*Promise, error) {
if hasHexPrefix(channelID) {
channelID = channelID[2:]
}
if hasHexPrefix(preimage) {
preimage = preimage[2:]
}
chID, err := hex.DecodeString(channelID)
if err != nil {
return nil, errors.Wrap(err, "Problem in decoding channelID")
}
r, err := hex.DecodeString(preimage)
if err != nil {
return nil, errors.Wrap(err, "Problem in decoding preimage")
}
sig, err := hex.DecodeString(signature)
if err != nil {
return nil, errors.Wrap(err, "Problem in decoding signature")
}
// hashlock := crypto.Keccak256(r)
promise := Promise{
ChannelID: chID,
Amount: new(big.Int).Set(amount),
Fee: new(big.Int).Set(fee),
Hashlock: crypto.Keccak256(r),
R: r,
Signature: sig,
ChainID: chainID,
}
return &promise, nil
}
// NewRawPromise creates a promise from given params. The promise has no R.
func NewRawPromise(chainID int64, channelID string, amount, fee *big.Int, hashlock string, signature string) (*Promise, error) {
if hasHexPrefix(channelID) {
channelID = channelID[2:]
}
if hasHexPrefix(hashlock) {
hashlock = hashlock[2:]
}
chID, err := hex.DecodeString(channelID)
if err != nil {
return nil, errors.Wrap(err, "Problem in decoding channelID")
}
hl, err := hex.DecodeString(hashlock)
if err != nil {
return nil, errors.Wrap(err, "Problem in decoding preimage")
}
sig, err := hex.DecodeString(signature)
if err != nil {
return nil, errors.Wrap(err, "Problem in decoding signature")
}
promise := Promise{
ChannelID: chID,
Amount: new(big.Int).Set(amount),
Fee: new(big.Int).Set(fee),
Hashlock: hl,
Signature: sig,
ChainID: chainID,
}
return &promise, nil
}
// Sign signs promise with given keystore and signer
func (p *Promise) Sign(ks *keystore.KeyStore, signer common.Address) error {
signature, err := p.CreateSignature(ks, signer)
if err != nil {
return err
}
if err := ReformatSignatureVForBC(signature); err != nil {
return fmt.Errorf("failed to reformat signature: %w", err)
}
p.Signature = signature
return nil
}
// GetMessage forms the message of payment promise
func (p Promise) GetMessage() []byte {
message := []byte{}
b := make([]byte, 8)
binary.BigEndian.PutUint64(b, uint64(p.ChainID))
message = append(message, Pad(b, 32)...)
message = append(message, Pad(p.ChannelID, 32)...)
message = append(message, Pad(math.U256(p.Amount).Bytes(), 32)...)
message = append(message, Pad(math.U256(p.Fee).Bytes(), 32)...)
message = append(message, Pad(p.Hashlock, 32)...)
return message
}
// GetHash returns a keccak of payment promise message
func (p Promise) GetHash() []byte {
return crypto.Keccak256(p.GetMessage())
}
// CreateSignature signs promise using keystore
func (p Promise) CreateSignature(ks hashSigner, signer common.Address) ([]byte, error) {
message := p.GetMessage()
hash := crypto.Keccak256(message)
return ks.SignHash(
accounts.Account{Address: signer},
hash,
)
}
// GetSignatureHexString returns signature in hex sting format
func (p Promise) GetSignatureHexString() string {
return "0x" + hex.EncodeToString(p.Signature)
}
// IsPromiseValid validates if given promise params are properly signed
func (p Promise) IsPromiseValid(expectedSigner common.Address) bool {
sig := make([]byte, 65)
copy(sig, p.Signature)
err := ReformatSignatureVForRecovery(sig)
if err != nil {
return false
}
recoveredSigner, err := RecoverAddress(p.GetMessage(), sig)
if err != nil {
return false
}
return recoveredSigner == expectedSigner
}
// RecoverSigner recovers signer address out of promise signature
func (p Promise) RecoverSigner() (common.Address, error) {
sig := make([]byte, 65)
copy(sig, p.Signature)
err := ReformatSignatureVForRecovery(sig)
if err != nil {
return common.Address{}, err
}
return RecoverAddress(p.GetMessage(), sig)
}