Implement Guaranteed Addresses

Closes https://github.com/serai-dex/serai/issues/27.

monero-rs is now solely used for Extra encoding.

coins/monero/src/wallet/address.rs

@@ -0,0 +1,152 @@
+use std::string::ToString;
+
+use thiserror::Error;
+
+use curve25519_dalek::{constants::ED25519_BASEPOINT_TABLE, edwards::{EdwardsPoint, CompressedEdwardsY}};
+
+use base58_monero::base58::{encode_check, decode_check};
+
+use crate::wallet::ViewPair;
+
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
+pub enum Network {
+  Mainnet,
+  Testnet,
+  Stagenet
+}
+
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
+pub enum AddressType {
+  Standard,
+  Integrated([u8; 8]),
+  Subaddress
+}
+
+impl AddressType {
+  fn network_bytes(network: Network) -> (u8, u8, u8) {
+    match network {
+      Network::Mainnet => (18, 19, 42),
+      Network::Testnet => (53, 54, 63),
+      Network::Stagenet => (24, 25, 36)
+    }
+  }
+}
+
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
+pub struct AddressMeta {
+  pub network: Network,
+  pub kind: AddressType,
+  pub guaranteed: bool
+}
+
+#[derive(Clone, Error, Debug)]
+pub enum AddressError {
+  #[error("invalid address byte")]
+  InvalidByte,
+  #[error("invalid address encoding")]
+  InvalidEncoding,
+  #[error("invalid length")]
+  InvalidLength,
+  #[error("different network than expected")]
+  DifferentNetwork,
+  #[error("invalid key")]
+  InvalidKey
+}
+
+impl AddressMeta {
+  fn to_byte(&self) -> u8 {
+    let bytes = AddressType::network_bytes(self.network);
+    let byte = match self.kind {
+      AddressType::Standard => bytes.0,
+      AddressType::Integrated(_) => bytes.1,
+      AddressType::Subaddress => bytes.2
+    };
+    byte | (if self.guaranteed { 1 << 7 } else { 0 })
+  }
+
+  // Returns an incomplete type in the case of Integrated addresses
+  fn from_byte(byte: u8) -> Result<AddressMeta, AddressError> {
+    let actual = byte & 0b01111111;
+    let guaranteed = (byte >> 7) == 1;
+
+    let mut meta = None;
+    for network in [Network::Mainnet, Network::Testnet, Network::Stagenet] {
+      let (standard, integrated, subaddress) = AddressType::network_bytes(network);
+      if let Some(kind) = match actual {
+        _ if actual == standard => Some(AddressType::Standard),
+        _ if actual == integrated => Some(AddressType::Integrated([0; 8])),
+        _ if actual == subaddress => Some(AddressType::Subaddress),
+        _ => None
+      } {
+        meta = Some(AddressMeta { network, kind, guaranteed });
+        break;
+      }
+    }
+
+    meta.ok_or(AddressError::InvalidByte)
+  }
+}
+
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
+pub struct Address {
+  pub meta: AddressMeta,
+  pub spend: EdwardsPoint,
+  pub view: EdwardsPoint
+}
+
+impl ViewPair {
+  pub fn address(&self, network: Network, kind: AddressType, guaranteed: bool) -> Address {
+    Address {
+      meta: AddressMeta {
+        network,
+        kind,
+        guaranteed
+      },
+      spend: self.spend,
+      view: &self.view * &ED25519_BASEPOINT_TABLE
+    }
+  }
+}
+
+impl ToString for Address {
+  fn to_string(&self) -> String {
+    let mut data = vec![self.meta.to_byte()];
+    data.extend(self.spend.compress().to_bytes());
+    data.extend(self.view.compress().to_bytes());
+    if let AddressType::Integrated(id) = self.meta.kind {
+      data.extend(id);
+    }
+    encode_check(&data).unwrap()
+  }
+}
+
+impl Address {
+  pub fn from_str(s: &str, network: Network) -> Result<Self, AddressError> {
+    let raw = decode_check(s).map_err(|_| AddressError::InvalidEncoding)?;
+    if raw.len() == 1 {
+      Err(AddressError::InvalidLength)?;
+    }
+
+    let mut meta = AddressMeta::from_byte(raw[0])?;
+    if meta.network != network {
+      Err(AddressError::DifferentNetwork)?;
+    }
+
+    let len = match meta.kind {
+      AddressType::Standard | AddressType::Subaddress => 65,
+      AddressType::Integrated(_) => 73
+    };
+    if raw.len() != len {
+      Err(AddressError::InvalidLength)?;
+    }
+
+    let spend = CompressedEdwardsY(raw[1 .. 33].try_into().unwrap()).decompress().ok_or(AddressError::InvalidKey)?;
+    let view = CompressedEdwardsY(raw[33 .. 65].try_into().unwrap()).decompress().ok_or(AddressError::InvalidKey)?;
+
+    if let AddressType::Integrated(ref mut payment_id) = meta.kind {
+      payment_id.copy_from_slice(&raw[65 .. 73]);
+    }
+
+    Ok(Address { meta, spend, view })
+  }
+}