Make coin a dedicated library

Closes https://github.com/serai-dex/serai/issues/128.

coin/Cargo.toml

@@ -0,0 +1,41 @@
+[package]
+name = "serai-coin"
+version = "0.1.0"
+description = "Abstract interface to represent a coin"
+license = "MIT"
+repository = "https://github.com/serai-dex/serai"
+authors = ["Luke Parker <lukeparker5132@gmail.com>"]
+keywords = []
+edition = "2021"
+publish = false
+
+[dependencies]
+async-trait = "0.1"
+thiserror = "1"
+
+curve25519-dalek = { version = "3", features = ["std"] }
+
+transcript = { package = "flexible-transcript", path = "../crypto/transcript", features = ["recommended"] }
+dalek-ff-group = { path = "../crypto/dalek-ff-group" }
+frost = { package = "modular-frost", path = "../crypto/frost", features = ["secp256k1", "ed25519"] }
+
+monero-serai = { path = "../coins/monero", features = ["multisig"] }
+
+# Test Dependencies
+rand_core = { version = "0.6", optional = true }
+
+group = { version = "0.12", optional = true }
+
+serde = { version = "1.0", features = ["derive"], optional = true }
+serde_json = { version = "1.0", optional = true }
+
+[dev-dependencies]
+rand_core = "0.6"
+
+group = "0.12"
+
+serde = { version = "1.0", features = ["derive"] }
+serde_json = "1.0"
+
+[features]
+test = ["rand_core", "group", "serde", "serde_json"]

coin/LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2022 Luke Parker
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

coin/src/lib.rs

@@ -0,0 +1,92 @@
+use std::marker::Send;
+
+use async_trait::async_trait;
+use thiserror::Error;
+
+use transcript::RecommendedTranscript;
+use frost::{curve::Curve, FrostKeys, sign::PreprocessMachine};
+
+pub(crate) mod utils;
+
+pub mod monero;
+pub use self::monero::Monero;
+
+#[derive(Clone, Error, Debug)]
+pub enum CoinError {
+  #[error("failed to connect to coin daemon")]
+  ConnectionError,
+}
+
+pub trait Output: Sized + Clone {
+  type Id: AsRef<[u8]>;
+
+  fn id(&self) -> Self::Id;
+  fn amount(&self) -> u64;
+
+  fn serialize(&self) -> Vec<u8>;
+  fn deserialize<R: std::io::Read>(reader: &mut R) -> std::io::Result<Self>;
+}
+
+#[async_trait]
+pub trait Coin {
+  type Curve: Curve;
+
+  type Fee: Copy;
+  type Transaction;
+  type Block;
+
+  type Output: Output;
+  type SignableTransaction;
+  type TransactionMachine: PreprocessMachine<Signature = Self::Transaction>;
+
+  type Address: Send;
+
+  const ID: &'static [u8];
+  const CONFIRMATIONS: usize;
+  const MAX_INPUTS: usize;
+  const MAX_OUTPUTS: usize; // TODO: Decide if this includes change or not
+
+  // Doesn't have to take self, enables some level of caching which is pleasant
+  fn address(&self, key: <Self::Curve as Curve>::G) -> Self::Address;
+
+  async fn get_latest_block_number(&self) -> Result<usize, CoinError>;
+  async fn get_block(&self, number: usize) -> Result<Self::Block, CoinError>;
+  async fn get_outputs(
+    &self,
+    block: &Self::Block,
+    key: <Self::Curve as Curve>::G,
+  ) -> Result<Vec<Self::Output>, CoinError>;
+
+  // TODO: Remove
+  async fn is_confirmed(&self, tx: &[u8]) -> Result<bool, CoinError>;
+
+  async fn prepare_send(
+    &self,
+    keys: FrostKeys<Self::Curve>,
+    transcript: RecommendedTranscript,
+    block_number: usize,
+    inputs: Vec<Self::Output>,
+    payments: &[(Self::Address, u64)],
+    fee: Self::Fee,
+  ) -> Result<Self::SignableTransaction, CoinError>;
+
+  async fn attempt_send(
+    &self,
+    transaction: Self::SignableTransaction,
+    included: &[u16],
+  ) -> Result<Self::TransactionMachine, CoinError>;
+
+  async fn publish_transaction(
+    &self,
+    tx: &Self::Transaction,
+  ) -> Result<(Vec<u8>, Vec<<Self::Output as Output>::Id>), CoinError>;
+
+  #[cfg(any(test, feature = "test"))]
+  async fn get_fee(&self) -> Self::Fee;
+
+  #[cfg(any(test, feature = "test"))]
+  async fn mine_block(&self);
+
+  #[cfg(any(test, feature = "test"))]
+  async fn test_send(&self, key: Self::Address);
+}

coin/src/monero.rs

@@ -0,0 +1,269 @@
+use async_trait::async_trait;
+
+use curve25519_dalek::scalar::Scalar;
+
+use dalek_ff_group as dfg;
+use transcript::RecommendedTranscript;
+use frost::{curve::Ed25519, FrostKeys};
+
+use monero_serai::{
+  transaction::Transaction,
+  block::Block,
+  rpc::Rpc,
+  wallet::{
+    ViewPair, Scanner,
+    address::{Network, Address},
+    Fee, SpendableOutput, SignableTransaction as MSignableTransaction, TransactionMachine,
+  },
+};
+
+use crate::{CoinError, Output as OutputTrait, Coin, utils::additional_key};
+
+#[derive(Clone, Debug)]
+pub struct Output(SpendableOutput);
+impl From<SpendableOutput> for Output {
+  fn from(output: SpendableOutput) -> Output {
+    Output(output)
+  }
+}
+
+impl OutputTrait for Output {
+  // While we could use (tx, o), using the key ensures we won't be susceptible to the burning bug.
+  // While the Monero library offers a variant which allows senders to ensure their TXs have unique
+  // output keys, Serai can still be targeted using the classic burning bug
+  type Id = [u8; 32];
+
+  fn id(&self) -> Self::Id {
+    self.0.output.data.key.compress().to_bytes()
+  }
+
+  fn amount(&self) -> u64 {
+    self.0.commitment().amount
+  }
+
+  fn serialize(&self) -> Vec<u8> {
+    self.0.serialize()
+  }
+
+  fn deserialize<R: std::io::Read>(reader: &mut R) -> std::io::Result<Self> {
+    SpendableOutput::deserialize(reader).map(Output)
+  }
+}
+
+#[derive(Debug)]
+pub struct SignableTransaction {
+  keys: FrostKeys<Ed25519>,
+  transcript: RecommendedTranscript,
+  // Monero height, defined as the length of the chain
+  height: usize,
+  actual: MSignableTransaction,
+}
+
+#[derive(Clone, Debug)]
+pub struct Monero {
+  pub(crate) rpc: Rpc,
+  view: Scalar,
+}
+
+impl Monero {
+  pub async fn new(url: String) -> Monero {
+    Monero { rpc: Rpc::new(url), view: additional_key::<Monero>(0).0 }
+  }
+
+  fn scanner(&self, spend: dfg::EdwardsPoint) -> Scanner {
+    Scanner::from_view(ViewPair::new(spend.0, self.view), Network::Mainnet, None)
+  }
+
+  #[cfg(any(test, feature = "test"))]
+  fn empty_scanner() -> Scanner {
+    use group::Group;
+    Scanner::from_view(
+      ViewPair::new(*dfg::EdwardsPoint::generator(), Scalar::one()),
+      Network::Mainnet,
+      Some(std::collections::HashSet::new()),
+    )
+  }
+
+  #[cfg(any(test, feature = "test"))]
+  fn empty_address() -> Address {
+    Self::empty_scanner().address()
+  }
+}
+
+#[async_trait]
+impl Coin for Monero {
+  type Curve = Ed25519;
+
+  type Fee = Fee;
+  type Transaction = Transaction;
+  type Block = Block;
+
+  type Output = Output;
+  type SignableTransaction = SignableTransaction;
+  type TransactionMachine = TransactionMachine;
+
+  type Address = Address;
+
+  const ID: &'static [u8] = b"Monero";
+  const CONFIRMATIONS: usize = 10;
+  // Testnet TX bb4d188a4c571f2f0de70dca9d475abc19078c10ffa8def26dd4f63ce1bcfd79 uses 146 inputs
+  // while using less than 100kb of space, albeit with just 2 outputs (though outputs share a BP)
+  // The TX size limit is half the contextual median block weight, where said weight is >= 300,000
+  // This means any TX which fits into 150kb will be accepted by Monero
+  // 128, even with 16 outputs, should fit into 100kb. Further efficiency by 192 may be viable
+  // TODO: Get hard numbers and tune
+  const MAX_INPUTS: usize = 128;
+  const MAX_OUTPUTS: usize = 16;
+
+  fn address(&self, key: dfg::EdwardsPoint) -> Self::Address {
+    self.scanner(key).address()
+  }
+
+  async fn get_latest_block_number(&self) -> Result<usize, CoinError> {
+    // Monero defines height as chain length, so subtract 1 for block number
+    Ok(self.rpc.get_height().await.map_err(|_| CoinError::ConnectionError)? - 1)
+  }
+
+  async fn get_block(&self, number: usize) -> Result<Self::Block, CoinError> {
+    self.rpc.get_block(number).await.map_err(|_| CoinError::ConnectionError)
+  }
+
+  async fn get_outputs(
+    &self,
+    block: &Self::Block,
+    key: dfg::EdwardsPoint,
+  ) -> Result<Vec<Self::Output>, CoinError> {
+    Ok(
+      self
+        .scanner(key)
+        .scan(&self.rpc, block)
+        .await
+        .map_err(|_| CoinError::ConnectionError)?
+        .iter()
+        .flat_map(|outputs| outputs.not_locked())
+        .map(Output::from)
+        .collect(),
+    )
+  }
+
+  async fn is_confirmed(&self, tx: &[u8]) -> Result<bool, CoinError> {
+    let tx_block_number =
+      self.rpc.get_transaction_block_number(tx).await.map_err(|_| CoinError::ConnectionError)?;
+    Ok((self.get_latest_block_number().await?.saturating_sub(tx_block_number) + 1) >= 10)
+  }
+
+  async fn prepare_send(
+    &self,
+    keys: FrostKeys<Ed25519>,
+    transcript: RecommendedTranscript,
+    block_number: usize,
+    mut inputs: Vec<Output>,
+    payments: &[(Address, u64)],
+    fee: Fee,
+  ) -> Result<SignableTransaction, CoinError> {
+    let spend = keys.group_key();
+    Ok(SignableTransaction {
+      keys,
+      transcript,
+      height: block_number + 1,
+      actual: MSignableTransaction::new(
+        self.rpc.get_protocol().await.unwrap(), // TODO: Make this deterministic
+        inputs.drain(..).map(|input| input.0).collect(),
+        payments.to_vec(),
+        Some(self.address(spend)),
+        None,
+        fee,
+      )
+      .map_err(|_| CoinError::ConnectionError)?,
+    })
+  }
+
+  async fn attempt_send(
+    &self,
+    transaction: SignableTransaction,
+    included: &[u16],
+  ) -> Result<Self::TransactionMachine, CoinError> {
+    transaction
+      .actual
+      .clone()
+      .multisig(
+        &self.rpc,
+        transaction.keys.clone(),
+        transaction.transcript.clone(),
+        transaction.height,
+        included.to_vec(),
+      )
+      .await
+      .map_err(|_| CoinError::ConnectionError)
+  }
+
+  async fn publish_transaction(
+    &self,
+    tx: &Self::Transaction,
+  ) -> Result<(Vec<u8>, Vec<<Self::Output as OutputTrait>::Id>), CoinError> {
+    self.rpc.publish_transaction(tx).await.map_err(|_| CoinError::ConnectionError)?;
+
+    Ok((tx.hash().to_vec(), tx.prefix.outputs.iter().map(|output| output.key.to_bytes()).collect()))
+  }
+
+  #[cfg(any(test, feature = "test"))]
+  async fn get_fee(&self) -> Self::Fee {
+    self.rpc.get_fee().await.unwrap()
+  }
+
+  #[cfg(any(test, feature = "test"))]
+  async fn mine_block(&self) {
+    #[derive(serde::Deserialize, Debug)]
+    struct EmptyResponse {}
+    let _: EmptyResponse = self
+      .rpc
+      .rpc_call(
+        "json_rpc",
+        Some(serde_json::json!({
+          "method": "generateblocks",
+          "params": {
+            "wallet_address": Self::empty_address().to_string(),
+            "amount_of_blocks": 10
+          },
+        })),
+      )
+      .await
+      .unwrap();
+  }
+
+  #[cfg(any(test, feature = "test"))]
+  async fn test_send(&self, address: Self::Address) {
+    use rand_core::OsRng;
+
+    let new_block = self.get_latest_block_number().await.unwrap() + 1;
+
+    self.mine_block().await;
+    for _ in 0 .. 7 {
+      self.mine_block().await;
+    }
+
+    let outputs = Self::empty_scanner()
+      .scan(&self.rpc, &self.rpc.get_block(new_block).await.unwrap())
+      .await
+      .unwrap()
+      .swap_remove(0)
+      .ignore_timelock();
+
+    let amount = outputs[0].commitment().amount;
+    let fee = 3000000000; // TODO
+    let tx = MSignableTransaction::new(
+      self.rpc.get_protocol().await.unwrap(),
+      outputs,
+      vec![(address, amount - fee)],
+      Some(Self::empty_address()),
+      None,
+      self.rpc.get_fee().await.unwrap(),
+    )
+    .unwrap()
+    .sign(&mut OsRng, &self.rpc, &Scalar::one())
+    .await
+    .unwrap();
+    self.rpc.publish_transaction(&tx).await.unwrap();
+    self.mine_block().await;
+  }
+}

coin/src/utils.rs

@@ -0,0 +1,11 @@
+use frost::curve::Curve;
+
+use crate::Coin;
+
+// Generate a static additional key for a given chain in a globally consistent manner
+// Doesn't consider the current group key to increase the simplicity of verifying Serai's status
+// Takes an index, k, to support protocols which use multiple secondary keys
+// Presumably a view key
+pub(crate) fn additional_key<C: Coin>(k: u64) -> <C::Curve as Curve>::F {
+  C::Curve::hash_to_F(b"Serai DEX Additional Key", &[C::ID, &k.to_le_bytes()].concat())
+}