xmr-btc-swap/swap/src/protocol/alice/state.rs
rishflab e5c0158597
Greatly reduce load onto the Electrum backend
We achieve our optimizations in three ways:

1. Batching calls instead of making them individually.

To get access to the batch calls, we replace all our
calls to the HTTP interface with RPC calls.

2. Never directly make network calls based on function
calls on the wallet.

Instead, inquiring about the status of a script always
just returns information based on local data. With every
call, we check when we last refreshed the local data and
do so if the data is considered to be too old. This
interval is configurable.

3. Use electrum's notification feature to get updated
with the latest blockheight.

Co-authored-by: Thomas Eizinger <thomas@eizinger.io>
Co-authored-by: Rishab Sharma <rishflab@hotmail.com>
2021-03-16 19:24:31 +11:00

364 lines
12 KiB
Rust

use crate::bitcoin::{
current_epoch, CancelTimelock, ExpiredTimelocks, PunishTimelock, TxCancel, TxPunish, TxRefund,
};
use crate::execution_params::ExecutionParams;
use crate::protocol::alice::{Message1, Message3};
use crate::protocol::bob::{Message0, Message2, Message4};
use crate::protocol::CROSS_CURVE_PROOF_SYSTEM;
use crate::{bitcoin, monero};
use anyhow::{anyhow, bail, Context, Result};
use libp2p::PeerId;
use monero_rpc::wallet::BlockHeight;
use rand::{CryptoRng, RngCore};
use serde::{Deserialize, Serialize};
use sigma_fun::ext::dl_secp256k1_ed25519_eq::CrossCurveDLEQProof;
use std::fmt;
#[derive(Debug)]
pub enum AliceState {
Started {
bob_peer_id: PeerId,
state3: Box<State3>,
},
BtcLocked {
bob_peer_id: PeerId,
state3: Box<State3>,
},
XmrLocked {
monero_wallet_restore_blockheight: BlockHeight,
state3: Box<State3>,
},
EncSigLearned {
monero_wallet_restore_blockheight: BlockHeight,
encrypted_signature: Box<bitcoin::EncryptedSignature>,
state3: Box<State3>,
},
BtcRedeemed,
BtcCancelled {
monero_wallet_restore_blockheight: BlockHeight,
tx_cancel: Box<TxCancel>,
state3: Box<State3>,
},
BtcRefunded {
monero_wallet_restore_blockheight: BlockHeight,
spend_key: monero::PrivateKey,
state3: Box<State3>,
},
BtcPunishable {
monero_wallet_restore_blockheight: BlockHeight,
tx_refund: Box<TxRefund>,
state3: Box<State3>,
},
XmrRefunded,
CancelTimelockExpired {
monero_wallet_restore_blockheight: BlockHeight,
state3: Box<State3>,
},
BtcPunished,
SafelyAborted,
}
impl fmt::Display for AliceState {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
AliceState::Started { .. } => write!(f, "started"),
AliceState::BtcLocked { .. } => write!(f, "btc is locked"),
AliceState::XmrLocked { .. } => write!(f, "xmr is locked"),
AliceState::EncSigLearned { .. } => write!(f, "encrypted signature is learned"),
AliceState::BtcRedeemed => write!(f, "btc is redeemed"),
AliceState::BtcCancelled { .. } => write!(f, "btc is cancelled"),
AliceState::BtcRefunded { .. } => write!(f, "btc is refunded"),
AliceState::BtcPunished => write!(f, "btc is punished"),
AliceState::SafelyAborted => write!(f, "safely aborted"),
AliceState::BtcPunishable { .. } => write!(f, "btc is punishable"),
AliceState::XmrRefunded => write!(f, "xmr is refunded"),
AliceState::CancelTimelockExpired { .. } => write!(f, "cancel timelock is expired"),
}
}
}
#[derive(Clone, Debug, Deserialize, Serialize, PartialEq)]
pub struct State0 {
pub a: bitcoin::SecretKey,
pub s_a: monero::Scalar,
pub v_a: monero::PrivateViewKey,
pub(crate) S_a_monero: monero::PublicKey,
pub(crate) S_a_bitcoin: bitcoin::PublicKey,
pub dleq_proof_s_a: CrossCurveDLEQProof,
#[serde(with = "::bitcoin::util::amount::serde::as_sat")]
pub btc: bitcoin::Amount,
pub xmr: monero::Amount,
pub cancel_timelock: CancelTimelock,
pub punish_timelock: PunishTimelock,
pub redeem_address: bitcoin::Address,
pub punish_address: bitcoin::Address,
}
impl State0 {
pub async fn new<R>(
btc: bitcoin::Amount,
xmr: monero::Amount,
execution_params: ExecutionParams,
bitcoin_wallet: &bitcoin::Wallet,
rng: &mut R,
) -> Result<Self>
where
R: RngCore + CryptoRng,
{
let a = bitcoin::SecretKey::new_random(rng);
let v_a = monero::PrivateViewKey::new_random(rng);
let redeem_address = bitcoin_wallet.new_address().await?;
let punish_address = redeem_address.clone();
let s_a = monero::Scalar::random(rng);
let (dleq_proof_s_a, (S_a_bitcoin, S_a_monero)) = CROSS_CURVE_PROOF_SYSTEM.prove(&s_a, rng);
Ok(Self {
a,
s_a,
v_a,
S_a_bitcoin: S_a_bitcoin.into(),
S_a_monero: monero::PublicKey {
point: S_a_monero.compress(),
},
dleq_proof_s_a,
redeem_address,
punish_address,
btc,
xmr,
cancel_timelock: execution_params.bitcoin_cancel_timelock,
punish_timelock: execution_params.bitcoin_punish_timelock,
})
}
pub fn receive(self, msg: Message0) -> Result<State1> {
let valid = CROSS_CURVE_PROOF_SYSTEM.verify(
&msg.dleq_proof_s_b,
(
msg.S_b_bitcoin.into(),
msg.S_b_monero
.point
.decompress()
.ok_or_else(|| anyhow!("S_b is not a monero curve point"))?,
),
);
if !valid {
bail!("Bob's dleq proof doesn't verify")
}
let v = self.v_a + msg.v_b;
Ok(State1 {
a: self.a,
B: msg.B,
s_a: self.s_a,
S_a_monero: self.S_a_monero,
S_a_bitcoin: self.S_a_bitcoin,
S_b_monero: msg.S_b_monero,
S_b_bitcoin: msg.S_b_bitcoin,
v,
v_a: self.v_a,
dleq_proof_s_a: self.dleq_proof_s_a,
btc: self.btc,
xmr: self.xmr,
cancel_timelock: self.cancel_timelock,
punish_timelock: self.punish_timelock,
refund_address: msg.refund_address,
redeem_address: self.redeem_address,
punish_address: self.punish_address,
})
}
}
#[derive(Clone, Debug, Deserialize, Serialize)]
pub struct State1 {
a: bitcoin::SecretKey,
B: bitcoin::PublicKey,
s_a: monero::Scalar,
S_a_monero: monero::PublicKey,
S_a_bitcoin: bitcoin::PublicKey,
S_b_monero: monero::PublicKey,
S_b_bitcoin: bitcoin::PublicKey,
v: monero::PrivateViewKey,
v_a: monero::PrivateViewKey,
dleq_proof_s_a: CrossCurveDLEQProof,
#[serde(with = "::bitcoin::util::amount::serde::as_sat")]
btc: bitcoin::Amount,
xmr: monero::Amount,
cancel_timelock: CancelTimelock,
punish_timelock: PunishTimelock,
refund_address: bitcoin::Address,
redeem_address: bitcoin::Address,
punish_address: bitcoin::Address,
}
impl State1 {
pub fn next_message(&self) -> Message1 {
Message1 {
A: self.a.public(),
S_a_monero: self.S_a_monero,
S_a_bitcoin: self.S_a_bitcoin,
dleq_proof_s_a: self.dleq_proof_s_a.clone(),
v_a: self.v_a,
redeem_address: self.redeem_address.clone(),
punish_address: self.punish_address.clone(),
}
}
pub fn receive(self, msg: Message2) -> State2 {
State2 {
a: self.a,
B: self.B,
s_a: self.s_a,
S_b_monero: self.S_b_monero,
S_b_bitcoin: self.S_b_bitcoin,
v: self.v,
btc: self.btc,
xmr: self.xmr,
cancel_timelock: self.cancel_timelock,
punish_timelock: self.punish_timelock,
refund_address: self.refund_address,
redeem_address: self.redeem_address,
punish_address: self.punish_address,
tx_lock: msg.tx_lock,
}
}
}
#[derive(Clone, Debug, Deserialize, Serialize)]
pub struct State2 {
a: bitcoin::SecretKey,
B: bitcoin::PublicKey,
s_a: monero::Scalar,
S_b_monero: monero::PublicKey,
S_b_bitcoin: bitcoin::PublicKey,
v: monero::PrivateViewKey,
#[serde(with = "::bitcoin::util::amount::serde::as_sat")]
btc: bitcoin::Amount,
xmr: monero::Amount,
cancel_timelock: CancelTimelock,
punish_timelock: PunishTimelock,
refund_address: bitcoin::Address,
redeem_address: bitcoin::Address,
punish_address: bitcoin::Address,
tx_lock: bitcoin::TxLock,
}
impl State2 {
pub fn next_message(&self) -> Message3 {
let tx_cancel =
bitcoin::TxCancel::new(&self.tx_lock, self.cancel_timelock, self.a.public(), self.B);
let tx_refund = bitcoin::TxRefund::new(&tx_cancel, &self.refund_address);
// Alice encsigns the refund transaction(bitcoin) digest with Bob's monero
// pubkey(S_b). The refund transaction spends the output of
// tx_lock_bitcoin to Bob's refund address.
// recover(encsign(a, S_b, d), sign(a, d), S_b) = s_b where d is a digest, (a,
// A) is alice's keypair and (s_b, S_b) is bob's keypair.
let tx_refund_encsig = self.a.encsign(self.S_b_bitcoin, tx_refund.digest());
let tx_cancel_sig = self.a.sign(tx_cancel.digest());
Message3 {
tx_refund_encsig,
tx_cancel_sig,
}
}
pub fn receive(self, msg: Message4) -> Result<State3> {
let tx_cancel =
bitcoin::TxCancel::new(&self.tx_lock, self.cancel_timelock, self.a.public(), self.B);
bitcoin::verify_sig(&self.B, &tx_cancel.digest(), &msg.tx_cancel_sig)
.context("Failed to verify cancel transaction")?;
let tx_punish =
bitcoin::TxPunish::new(&tx_cancel, &self.punish_address, self.punish_timelock);
bitcoin::verify_sig(&self.B, &tx_punish.digest(), &msg.tx_punish_sig)
.context("Failed to verify punish transaction")?;
Ok(State3 {
a: self.a,
B: self.B,
s_a: self.s_a,
S_b_monero: self.S_b_monero,
S_b_bitcoin: self.S_b_bitcoin,
v: self.v,
btc: self.btc,
xmr: self.xmr,
cancel_timelock: self.cancel_timelock,
punish_timelock: self.punish_timelock,
refund_address: self.refund_address,
redeem_address: self.redeem_address,
punish_address: self.punish_address,
tx_lock: self.tx_lock,
tx_punish_sig_bob: msg.tx_punish_sig,
tx_cancel_sig_bob: msg.tx_cancel_sig,
})
}
}
#[derive(Clone, Debug, Deserialize, Serialize, PartialEq)]
pub struct State3 {
pub a: bitcoin::SecretKey,
pub B: bitcoin::PublicKey,
pub s_a: monero::Scalar,
pub S_b_monero: monero::PublicKey,
pub S_b_bitcoin: bitcoin::PublicKey,
pub v: monero::PrivateViewKey,
#[serde(with = "::bitcoin::util::amount::serde::as_sat")]
pub btc: bitcoin::Amount,
pub xmr: monero::Amount,
pub cancel_timelock: CancelTimelock,
pub punish_timelock: PunishTimelock,
pub refund_address: bitcoin::Address,
pub redeem_address: bitcoin::Address,
pub punish_address: bitcoin::Address,
pub tx_lock: bitcoin::TxLock,
pub tx_punish_sig_bob: bitcoin::Signature,
pub tx_cancel_sig_bob: bitcoin::Signature,
}
impl State3 {
pub async fn wait_for_cancel_timelock_to_expire(
&self,
bitcoin_wallet: &bitcoin::Wallet,
) -> Result<()> {
bitcoin_wallet
.watch_until_status(
self.tx_lock.txid(),
self.tx_lock.script_pubkey(),
|status| status.is_confirmed_with(self.cancel_timelock),
)
.await?;
Ok(())
}
pub async fn expired_timelocks(
&self,
bitcoin_wallet: &bitcoin::Wallet,
) -> Result<ExpiredTimelocks> {
let tx_cancel = TxCancel::new(&self.tx_lock, self.cancel_timelock, self.a.public(), self.B);
let tx_lock_status = bitcoin_wallet
.status_of_script(&self.tx_lock.script_pubkey(), &self.tx_lock.txid())
.await?;
let tx_cancel_status = bitcoin_wallet
.status_of_script(&tx_cancel.script_pubkey(), &tx_cancel.txid())
.await?;
Ok(current_epoch(
self.cancel_timelock,
self.punish_timelock,
tx_lock_status,
tx_cancel_status,
))
}
pub fn tx_punish(&self) -> TxPunish {
let tx_cancel =
bitcoin::TxCancel::new(&self.tx_lock, self.cancel_timelock, self.a.public(), self.B);
bitcoin::TxPunish::new(&tx_cancel, &self.punish_address, self.punish_timelock)
}
}