Generate Bulletproofs(+) generators at compile time

Creates a new monero-generators crate so the monero crate can run the 
code in question at build time.

Saves several seconds from running the tests.

Closes https://github.com/serai-dex/serai/issues/101.

Cargo.lock

@@ -4583,6 +4583,18 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "monero-generators"
+version = "0.1.0"
+dependencies = [
+ "curve25519-dalek 3.2.0",
+ "dalek-ff-group",
+ "group",
+ "lazy_static",
+ "subtle",
+ "tiny-keccak",
+]
+
 [[package]]
 name = "monero-serai"
 version = "0.1.0"
@@ -4600,6 +4612,7 @@ dependencies = [
  "modular-frost",
  "monero",
  "monero-epee-bin-serde",
+ "monero-generators",
  "multiexp",
  "rand 0.8.5",
  "rand_chacha 0.3.1",
@@ -4608,7 +4621,6 @@ dependencies = [
  "reqwest",
  "serde",
  "serde_json",
- "sha2 0.10.2",
  "subtle",
  "thiserror",
  "tiny-keccak",

Cargo.toml

@@ -9,6 +9,7 @@ members = [
   "crypto/frost",
 
   "coins/ethereum",
+  "coins/monero/generators",
   "coins/monero",
 
   "processor",

coins/monero/.gitignore

@@ -0,0 +1 @@
+.generators

coins/monero/Cargo.toml

@@ -32,6 +32,8 @@ transcript = { package = "flexible-transcript", path = "../../crypto/transcript"
 frost = { package = "modular-frost", path = "../../crypto/frost", features = ["ed25519"], optional = true }
 dleq = { path = "../../crypto/dleq", features = ["serialize"], optional = true }
 
+monero-generators = { path = "generators" }
+
 hex = "0.4"
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
@@ -45,6 +47,9 @@ reqwest = { version = "0.11", features = ["json"] }
 [features]
 multisig = ["rand_chacha", "blake2", "transcript", "frost", "dleq"]
 
+[build-dependencies]
+dalek-ff-group = { path = "../../crypto/dalek-ff-group" }
+monero-generators = { path = "generators" }
+
 [dev-dependencies]
-sha2 = "0.10"
 tokio = { version = "1", features = ["full"] }

coins/monero/build.rs

@@ -0,0 +1,67 @@
+use std::{
+  io::Write,
+  path::Path,
+  fs::{File, remove_file},
+};
+
+use dalek_ff_group::EdwardsPoint;
+
+use monero_generators::bulletproofs_generators;
+
+fn serialize(generators_string: &mut String, points: &[EdwardsPoint]) {
+  for generator in points {
+    generators_string.extend(
+      format!(
+        "
+          dalek_ff_group::EdwardsPoint(
+            curve25519_dalek::edwards::CompressedEdwardsY({:?}).decompress().unwrap()
+          ),
+        ",
+        generator.compress().to_bytes()
+      )
+      .chars(),
+    );
+  }
+}
+
+fn generators(prefix: &'static str, path: &str) {
+  let generators = bulletproofs_generators(prefix.as_bytes());
+  #[allow(non_snake_case)]
+  let mut G_str = "".to_string();
+  serialize(&mut G_str, &generators.G);
+  #[allow(non_snake_case)]
+  let mut H_str = "".to_string();
+  serialize(&mut H_str, &generators.H);
+
+  let path = Path::new(".generators").join(path);
+  let _ = remove_file(&path);
+  File::create(&path)
+    .unwrap()
+    .write_all(
+      format!(
+        "
+          lazy_static! {{
+            static ref GENERATORS: Generators = Generators {{
+              G: [
+                {}
+              ],
+              H: [
+                {}
+              ],
+            }};
+          }}
+        ",
+        G_str, H_str,
+      )
+      .as_bytes(),
+    )
+    .unwrap();
+}
+
+fn main() {
+  // For some reason, filtering off .generators does not work. This prevents re-building overall
+  println!("cargo:rerun-if-changed=build.rs");
+
+  generators("bulletproof", "generators.rs");
+  generators("bulletproof_plus", "generators_plus.rs");
+}

coins/monero/generators/Cargo.toml

@@ -0,0 +1,19 @@
+[package]
+name = "monero-generators"
+version = "0.1.0"
+description = "Monero's hash_to_point and generators"
+license = "MIT"
+authors = ["Luke Parker <lukeparker5132@gmail.com>"]
+edition = "2021"
+
+[dependencies]
+lazy_static = "1"
+
+subtle = "2.4"
+
+tiny-keccak = { version = "2", features = ["keccak"] }
+
+curve25519-dalek = { version = "3", features = ["std"] }
+
+group = { version = "0.12" }
+dalek-ff-group = { path = "../../../crypto/dalek-ff-group" }

coins/monero/generators/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.

coins/monero/generators/src/hash_to_point.rs

@@ -0,0 +1,51 @@
+use subtle::ConditionallySelectable;
+
+use curve25519_dalek::edwards::{EdwardsPoint, CompressedEdwardsY};
+
+use group::ff::{Field, PrimeField};
+use dalek_ff_group::field::FieldElement;
+
+use crate::hash;
+
+#[allow(dead_code)]
+pub fn hash_to_point(bytes: [u8; 32]) -> EdwardsPoint {
+  #[allow(non_snake_case)]
+  let A = FieldElement::from(486662u64);
+
+  let v = FieldElement::from_square(hash(&bytes)).double();
+  let w = v + FieldElement::one();
+  let x = w.square() + (-A.square() * v);
+
+  // This isn't the complete X, yet its initial value
+  // We don't calculate the full X, and instead solely calculate Y, letting dalek reconstruct X
+  // While inefficient, it solves API boundaries and reduces the amount of work done here
+  #[allow(non_snake_case)]
+  let X = {
+    let u = w;
+    let v = x;
+    let v3 = v * v * v;
+    let uv3 = u * v3;
+    let v7 = v3 * v3 * v;
+    let uv7 = u * v7;
+    uv3 * uv7.pow((-FieldElement::from(5u8)) * FieldElement::from(8u8).invert().unwrap())
+  };
+  let x = X.square() * x;
+
+  let y = w - x;
+  let non_zero_0 = !y.is_zero();
+  let y_if_non_zero_0 = w + x;
+  let sign = non_zero_0 & (!y_if_non_zero_0.is_zero());
+
+  let mut z = -A;
+  z *= FieldElement::conditional_select(&v, &FieldElement::from(1u8), sign);
+  #[allow(non_snake_case)]
+  let Z = z + w;
+  #[allow(non_snake_case)]
+  let mut Y = z - w;
+
+  Y *= Z.invert().unwrap();
+  let mut bytes = Y.to_repr();
+  bytes[31] |= sign.unwrap_u8() << 7;
+
+  CompressedEdwardsY(bytes).decompress().unwrap().mul_by_cofactor()
+}

coins/monero/generators/src/lib.rs

@@ -0,0 +1,61 @@
+use lazy_static::lazy_static;
+
+use tiny_keccak::{Hasher, Keccak};
+
+use curve25519_dalek::{
+  constants::ED25519_BASEPOINT_POINT,
+  edwards::{EdwardsPoint as DalekPoint, CompressedEdwardsY},
+};
+
+use group::Group;
+use dalek_ff_group::EdwardsPoint;
+
+mod varint;
+use varint::write_varint;
+
+mod hash_to_point;
+pub use hash_to_point::hash_to_point;
+
+fn hash(data: &[u8]) -> [u8; 32] {
+  let mut keccak = Keccak::v256();
+  keccak.update(data);
+  let mut res = [0; 32];
+  keccak.finalize(&mut res);
+  res
+}
+
+lazy_static! {
+  pub static ref H: DalekPoint =
+    CompressedEdwardsY(hash(&ED25519_BASEPOINT_POINT.compress().to_bytes()))
+      .decompress()
+      .unwrap()
+      .mul_by_cofactor();
+}
+
+const MAX_M: usize = 16;
+const N: usize = 64;
+const MAX_MN: usize = MAX_M * N;
+
+#[allow(non_snake_case)]
+pub struct Generators {
+  pub G: [EdwardsPoint; MAX_MN],
+  pub H: [EdwardsPoint; MAX_MN],
+}
+
+pub fn bulletproofs_generators(prefix: &'static [u8]) -> Generators {
+  let mut res =
+    Generators { G: [EdwardsPoint::identity(); MAX_MN], H: [EdwardsPoint::identity(); MAX_MN] };
+  for i in 0 .. MAX_MN {
+    let i = 2 * i;
+
+    let mut even = H.compress().to_bytes().to_vec();
+    even.extend(prefix);
+    let mut odd = even.clone();
+
+    write_varint(&i.try_into().unwrap(), &mut even).unwrap();
+    write_varint(&(i + 1).try_into().unwrap(), &mut odd).unwrap();
+    res.H[i / 2] = EdwardsPoint(hash_to_point(hash(&even)));
+    res.G[i / 2] = EdwardsPoint(hash_to_point(hash(&odd)));
+  }
+  res
+}

coins/monero/generators/src/varint.rs

@@ -0,0 +1,16 @@
+use std::io;
+
+const VARINT_CONTINUATION_MASK: u8 = 0b1000_0000;
+pub(crate) fn write_varint<W: io::Write>(varint: &u64, w: &mut W) -> io::Result<()> {
+  let mut varint = *varint;
+  while {
+    let mut b = u8::try_from(varint & u64::from(!VARINT_CONTINUATION_MASK)).unwrap();
+    varint >>= 7;
+    if varint != 0 {
+      b |= VARINT_CONTINUATION_MASK;
+    }
+    w.write_all(&[b])?;
+    varint != 0
+  } {}
+  Ok(())
+}

coins/monero/src/lib.rs

@@ -6,11 +6,13 @@ use zeroize::{Zeroize, ZeroizeOnDrop};
 use tiny_keccak::{Hasher, Keccak};
 
 use curve25519_dalek::{
-  constants::{ED25519_BASEPOINT_POINT, ED25519_BASEPOINT_TABLE},
+  constants::ED25519_BASEPOINT_TABLE,
   scalar::Scalar,
-  edwards::{EdwardsPoint, EdwardsBasepointTable, CompressedEdwardsY},
+  edwards::{EdwardsPoint, EdwardsBasepointTable},
 };
 
+pub use monero_generators::H;
+
 #[cfg(feature = "multisig")]
 pub mod frost;
 
@@ -54,11 +56,6 @@ impl Protocol {
 }
 
 lazy_static! {
-  static ref H: EdwardsPoint =
-    CompressedEdwardsY(hash(&ED25519_BASEPOINT_POINT.compress().to_bytes()))
-      .decompress()
-      .unwrap()
-      .mul_by_cofactor();
   static ref H_TABLE: EdwardsBasepointTable = EdwardsBasepointTable::create(&H);
 }
 

coins/monero/src/ringct/bulletproofs/core.rs

@@ -13,10 +13,9 @@ use dalek_ff_group::{Scalar, EdwardsPoint};
 
 use multiexp::multiexp as multiexp_const;
 
-use crate::{
-  H as DALEK_H, Commitment, hash, hash_to_scalar as dalek_hash,
-  ringct::hash_to_point::raw_hash_to_point, serialize::write_varint,
-};
+pub(crate) use monero_generators::Generators;
+
+use crate::{H as DALEK_H, Commitment, hash_to_scalar as dalek_hash};
 pub(crate) use crate::ringct::bulletproofs::scalar_vector::*;
 
 // Bring things into ff/group
@@ -33,29 +32,6 @@ pub(crate) fn hash_to_scalar(data: &[u8]) -> Scalar {
 pub(crate) const MAX_M: usize = 16;
 pub(crate) const LOG_N: usize = 6; // 2 << 6 == N
 pub(crate) const N: usize = 64;
-pub(crate) const MAX_MN: usize = MAX_M * N;
-
-pub(crate) struct Generators {
-  pub(crate) G: Vec<EdwardsPoint>,
-  pub(crate) H: Vec<EdwardsPoint>,
-}
-
-pub(crate) fn generators_core(prefix: &'static [u8]) -> Generators {
-  let mut res = Generators { G: Vec::with_capacity(MAX_MN), H: Vec::with_capacity(MAX_MN) };
-  for i in 0 .. MAX_MN {
-    let i = 2 * i;
-
-    let mut even = (*H).compress().to_bytes().to_vec();
-    even.extend(prefix);
-    let mut odd = even.clone();
-
-    write_varint(&i.try_into().unwrap(), &mut even).unwrap();
-    write_varint(&(i + 1).try_into().unwrap(), &mut odd).unwrap();
-    res.H.push(EdwardsPoint(raw_hash_to_point(hash(&even))));
-    res.G.push(EdwardsPoint(raw_hash_to_point(hash(&odd))));
-  }
-  res
-}
 
 pub(crate) fn prove_multiexp(pairs: &[(Scalar, EdwardsPoint)]) -> EdwardsPoint {
   multiexp_const(pairs) * *INV_EIGHT
@@ -153,12 +129,6 @@ lazy_static! {
   pub(crate) static ref TWO_N: ScalarVector = ScalarVector::powers(Scalar::from(2u8), N);
 }
 
-pub(crate) fn init() {
-  let _ = &*INV_EIGHT;
-  let _ = &*H;
-  let _ = &*TWO_N;
-}
-
 pub(crate) fn challenge_products(w: &[Scalar], winv: &[Scalar]) -> Vec<Scalar> {
   let mut products = vec![Scalar::zero(); 1 << w.len()];
   products[0] = winv[0];

coins/monero/src/ringct/bulletproofs/mod.rs

@@ -43,14 +43,6 @@ impl Bulletproofs {
     len + clawback
   }
 
-  pub fn init(plus: bool) {
-    if !plus {
-      OriginalStruct::init();
-    } else {
-      PlusStruct::init();
-    }
-  }
-
   pub fn prove<R: RngCore + CryptoRng>(
     rng: &mut R,
     outputs: &[Commitment],

coins/monero/src/ringct/bulletproofs/original.rs

@@ -12,8 +12,9 @@ use multiexp::BatchVerifier;
 
 use crate::{Commitment, ringct::bulletproofs::core::*};
 
+include!("../../../.generators/generators.rs");
+
 lazy_static! {
-  static ref GENERATORS: Generators = generators_core(b"bulletproof");
   static ref ONE_N: ScalarVector = ScalarVector(vec![Scalar::one(); N]);
   static ref IP12: Scalar = inner_product(&ONE_N, &TWO_N);
 }
@@ -34,13 +35,6 @@ pub struct OriginalStruct {
 }
 
 impl OriginalStruct {
-  pub(crate) fn init() {
-    init();
-    let _ = &*GENERATORS;
-    let _ = &*ONE_N;
-    let _ = &*IP12;
-  }
-
   pub(crate) fn prove<R: RngCore + CryptoRng>(
     rng: &mut R,
     commitments: &[Commitment],

coins/monero/src/ringct/bulletproofs/plus.rs

@@ -15,8 +15,9 @@ use crate::{
   ringct::{hash_to_point::raw_hash_to_point, bulletproofs::core::*},
 };
 
+include!("../../../.generators/generators_plus.rs");
+
 lazy_static! {
-  static ref GENERATORS: Generators = generators_core(b"bulletproof_plus");
   static ref TRANSCRIPT: [u8; 32] =
     EdwardsPoint(raw_hash_to_point(hash(b"bulletproof_plus_transcript"))).compress().to_bytes();
 }
@@ -52,12 +53,6 @@ pub struct PlusStruct {
 }
 
 impl PlusStruct {
-  pub(crate) fn init() {
-    init();
-    let _ = &*GENERATORS;
-    let _ = &*TRANSCRIPT;
-  }
-
   pub(crate) fn prove<R: RngCore + CryptoRng>(
     rng: &mut R,
     commitments: &[Commitment],

coins/monero/src/ringct/hash_to_point.rs

@@ -1,54 +1,6 @@
-use subtle::ConditionallySelectable;
+use curve25519_dalek::edwards::EdwardsPoint;
 
-use curve25519_dalek::edwards::{CompressedEdwardsY, EdwardsPoint};
-
-use group::ff::{Field, PrimeField};
-use dalek_ff_group::field::FieldElement;
-
-use crate::hash;
-
-#[allow(dead_code)]
-pub(crate) fn raw_hash_to_point(bytes: [u8; 32]) -> EdwardsPoint {
-  #[allow(non_snake_case)]
-  let A = FieldElement::from(486662u64);
-
-  let v = FieldElement::from_square(hash(&bytes)).double();
-  let w = v + FieldElement::one();
-  let x = w.square() + (-A.square() * v);
-
-  // This isn't the complete X, yet its initial value
-  // We don't calculate the full X, and instead solely calculate Y, letting dalek reconstruct X
-  // While inefficient, it solves API boundaries and reduces the amount of work done here
-  #[allow(non_snake_case)]
-  let X = {
-    let u = w;
-    let v = x;
-    let v3 = v * v * v;
-    let uv3 = u * v3;
-    let v7 = v3 * v3 * v;
-    let uv7 = u * v7;
-    uv3 * uv7.pow((-FieldElement::from(5u8)) * FieldElement::from(8u8).invert().unwrap())
-  };
-  let x = X.square() * x;
-
-  let y = w - x;
-  let non_zero_0 = !y.is_zero();
-  let y_if_non_zero_0 = w + x;
-  let sign = non_zero_0 & (!y_if_non_zero_0.is_zero());
-
-  let mut z = -A;
-  z *= FieldElement::conditional_select(&v, &FieldElement::from(1u8), sign);
-  #[allow(non_snake_case)]
-  let Z = z + w;
-  #[allow(non_snake_case)]
-  let mut Y = z - w;
-
-  Y *= Z.invert().unwrap();
-  let mut bytes = Y.to_repr();
-  bytes[31] |= sign.unwrap_u8() << 7;
-
-  CompressedEdwardsY(bytes).decompress().unwrap().mul_by_cofactor()
-}
+pub(crate) use monero_generators::{hash_to_point as raw_hash_to_point};
 
 pub fn hash_to_point(key: EdwardsPoint) -> EdwardsPoint {
   raw_hash_to_point(key.compress().to_bytes())

coins/monero/src/tests/bulletproofs.rs

@@ -57,12 +57,7 @@ fn bulletproofs_vector() {
 }
 
 macro_rules! bulletproofs_tests {
-  ($init: ident, $name: ident, $max: ident, $plus: literal) => {
-    #[test]
-    fn $init() {
-      Bulletproofs::init($plus);
-    }
-
+  ($name: ident, $max: ident, $plus: literal) => {
     #[test]
     fn $name() {
       // Create Bulletproofs for all possible output quantities
@@ -93,5 +88,5 @@ macro_rules! bulletproofs_tests {
   };
 }
 
-bulletproofs_tests!(bulletproofs_init, bulletproofs, bulletproofs_max, false);
-bulletproofs_tests!(bulletproofs_plus_init, bulletproofs_plus, bulletproofs_plus_max, true);
+bulletproofs_tests!(bulletproofs, bulletproofs_max, false);
+bulletproofs_tests!(bulletproofs_plus, bulletproofs_plus_max, true);

processor/src/coin/monero.rs

@@ -7,7 +7,6 @@ use transcript::RecommendedTranscript;
 use frost::{curve::Ed25519, FrostKeys};
 
 use monero_serai::{
-  ringct::bulletproofs::Bulletproofs,
   transaction::Transaction,
   rpc::Rpc,
   wallet::{
@@ -69,14 +68,7 @@ pub struct Monero {
 
 impl Monero {
   pub async fn new(url: String) -> Monero {
-    let view = view_key::<Monero>(0).0;
-    let res = Monero { rpc: Rpc::new(url), view };
-
-    // Initialize Bulletproofs now to prevent the first call from taking several seconds
-    // TODO: Do this for both, unless we're sure we're only working on a single protocol
-    Bulletproofs::init(res.rpc.get_protocol().await.unwrap().bp_plus());
-
-    res
+    Monero { rpc: Rpc::new(url), view: view_key::<Monero>(0).0 }
   }
 
   fn view_pair(&self, spend: dfg::EdwardsPoint) -> ViewPair {

processor/src/wallet.rs

@@ -86,7 +86,7 @@ impl CoinDb for MemCoinDb {
   fn add_output<O: Output>(&mut self, output: &O) -> bool {
     // This would be insecure as we're indexing by ID and this will replace the output as a whole
     // Multiple outputs may have the same ID in edge cases such as Monero, where outputs are ID'd
-    // by key image, not by hash + index
+    // by output key, not by hash + index
     // self.outputs.insert(output.id(), output).is_some()
     let id = output.id().as_ref().to_vec();
     if self.outputs.contains_key(&id) {