Move the Monero create to coins/

Includes misc bug fixes

coins/monero/src/lib.rs

@@ -0,0 +1,82 @@
+use lazy_static::lazy_static;
+use thiserror::Error;
+
+use rand_core::{RngCore, CryptoRng};
+
+use tiny_keccak::{Hasher, Keccak};
+
+use curve25519_dalek::{
+  constants::ED25519_BASEPOINT_TABLE,
+  scalar::Scalar,
+  edwards::{EdwardsPoint, EdwardsBasepointTable, CompressedEdwardsY}
+};
+
+use monero::util::key;
+
+#[cfg(feature = "multisig")]
+pub mod frost;
+
+pub mod key_image;
+pub mod clsag;
+
+#[link(name = "wrapper")]
+extern "C" {
+  fn c_hash_to_point(point: *const u8);
+  pub(crate) fn c_verify_clsag(
+    serialized_len: usize, serialized: *const u8, I: *const u8,
+    ring_size: u8, ring: *const u8, msg: *const u8, pseudo_out: *const u8
+  ) -> bool;
+}
+
+#[derive(Error, Debug)]
+pub enum SignError {
+  #[error("internal error ({0})")]
+  InternalError(String),
+  #[error("invalid discrete log equality proof")]
+  InvalidDLEqProof,
+  #[error("invalid key image {0}")]
+  InvalidKeyImage(usize),
+  #[error("invalid ring member (member {0}, ring size {1})")]
+  InvalidRingMember(u8, u8),
+  #[error("invalid secret for ring (index {0})")]
+  InvalidSecret(u8),
+  #[error("invalid commitment {0}")]
+  InvalidCommitment(usize),
+  #[error("invalid share {0}")]
+  InvalidShare(usize),
+  #[error("invalid signature")]
+  InvalidSignature
+}
+
+// Allows using a modern rand as dalek's is notoriously dated
+pub fn random_scalar<R: RngCore + CryptoRng>(rng: &mut R) -> Scalar {
+  let mut r = [0; 64];
+  rng.fill_bytes(&mut r);
+  Scalar::from_bytes_mod_order_wide(&r)
+}
+
+lazy_static! {
+  static ref H_TABLE: EdwardsBasepointTable = EdwardsBasepointTable::create(&key::H.point.decompress().unwrap());
+}
+
+// aG + bH
+pub fn commitment(randomness: &Scalar, amount: u64) -> EdwardsPoint {
+  (randomness * &ED25519_BASEPOINT_TABLE) + (&Scalar::from(amount) * &*H_TABLE)
+}
+
+pub fn hash_to_scalar(data: &[u8]) -> Scalar {
+  let mut keccak = Keccak::v256();
+  keccak.update(data);
+
+  let mut res = [0; 32];
+  keccak.finalize(&mut res);
+  Scalar::from_bytes_mod_order(res)
+}
+
+pub fn hash_to_point(point: &EdwardsPoint) -> EdwardsPoint {
+  let mut bytes = point.compress().to_bytes();
+  unsafe {
+    c_hash_to_point(bytes.as_mut_ptr());
+  }
+  CompressedEdwardsY::from_slice(&bytes).decompress().unwrap()
+}