[ep-core] introduce Bip340 struct (#350)

* [ep-core] introduce Bip340 struct

* fix unused imports

* fix no-std

* fix no-std 2

* fix no-std 3

* fix no-std 4

* fix no-std 5

* fix no-std in democracy

* fix no-std final

* fix clippy

(cherry picked from commit 94cbcca)

primitives/core/Cargo.toml

@@ -4,6 +4,7 @@ name = "ep-core"
 version = "1.2.0"
 
 [dependencies]
+array-bytes = "6.1.0"
 codec = { package = "parity-scale-codec", version = "3.6.1", default-features = false, features = [
     "derive",
 ] }

primitives/core/src/bip340.rs

@@ -0,0 +1,202 @@
+use codec::{Decode, Encode, MaxEncodedLen};
+use scale_info::TypeInfo;
+use sp_core::{
+	crypto::{AccountId32, ByteArray},
+	ed25519, sr25519,
+};
+
+/// An opaque 32-byte cryptographic identifier.
+///
+/// Very similar to the `AccountId32`, but it is purposely different
+/// as it does not implement the SS58 codec.
+#[derive(Clone, Eq, PartialEq, Ord, PartialOrd, Encode, Decode, MaxEncodedLen, TypeInfo)]
+pub struct Bip340([u8; 32]);
+
+impl Bip340 {
+	/// Create a new instance from its raw inner byte value.
+	///
+	/// Equivalent to this types `From<[u8; 32]>` implementation. For the lack of const
+	/// support in traits we have this constructor.
+	pub const fn new(inner: [u8; 32]) -> Self {
+		Self(inner)
+	}
+}
+
+impl ByteArray for Bip340 {
+	const LEN: usize = 32;
+}
+
+impl AsRef<[u8]> for Bip340 {
+	fn as_ref(&self) -> &[u8] {
+		&self.0[..]
+	}
+}
+
+impl AsMut<[u8]> for Bip340 {
+	fn as_mut(&mut self) -> &mut [u8] {
+		&mut self.0[..]
+	}
+}
+
+impl AsRef<[u8; 32]> for Bip340 {
+	fn as_ref(&self) -> &[u8; 32] {
+		&self.0
+	}
+}
+
+impl AsMut<[u8; 32]> for Bip340 {
+	fn as_mut(&mut self) -> &mut [u8; 32] {
+		&mut self.0
+	}
+}
+
+impl From<[u8; 32]> for Bip340 {
+	fn from(x: [u8; 32]) -> Self {
+		Self::new(x)
+	}
+}
+
+impl<'a> TryFrom<&'a [u8]> for Bip340 {
+	type Error = ();
+	fn try_from(x: &'a [u8]) -> Result<Bip340, ()> {
+		if x.len() == 32 {
+			let mut data = [0; 32];
+			data.copy_from_slice(x);
+			Ok(Bip340(data))
+		} else {
+			Err(())
+		}
+	}
+}
+
+impl From<Bip340> for [u8; 32] {
+	fn from(x: Bip340) -> [u8; 32] {
+		x.0
+	}
+}
+
+impl From<Bip340> for AccountId32 {
+	fn from(x: Bip340) -> AccountId32 {
+		x.0.into()
+	}
+}
+
+impl From<sr25519::Public> for Bip340 {
+	fn from(k: sr25519::Public) -> Self {
+		k.0.into()
+	}
+}
+
+impl From<ed25519::Public> for Bip340 {
+	fn from(k: ed25519::Public) -> Self {
+		k.0.into()
+	}
+}
+
+impl core::fmt::Display for Bip340 {
+	fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
+		write!(f, "0x{}", sp_core::hexdisplay::HexDisplay::from(&self.0))
+	}
+}
+
+impl core::fmt::Debug for Bip340 {
+	fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
+		write!(f, "0x{}", sp_core::hexdisplay::HexDisplay::from(&self.0))
+	}
+}
+
+#[cfg(feature = "serde_derive")]
+impl serde::Serialize for Bip340 {
+	fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+	where
+		S: serde::Serializer,
+	{
+		#[cfg(not(feature = "std"))]
+		use codec::alloc::string::ToString;
+		serializer.serialize_str(&self.to_string())
+	}
+}
+
+#[cfg(feature = "serde_derive")]
+impl<'de> serde::Deserialize<'de> for Bip340 {
+	fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+	where
+		D: serde::Deserializer<'de>,
+	{
+		#[cfg(not(feature = "std"))]
+		use codec::alloc::string::String;
+		sp_std::str::FromStr::from_str(&String::deserialize(deserializer)?)
+			.map_err(serde::de::Error::custom)
+	}
+}
+
+impl sp_std::str::FromStr for Bip340 {
+	type Err = &'static str;
+
+	fn from_str(s: &str) -> Result<Self, Self::Err> {
+		array_bytes::hex_n_into(s.trim_start_matches("0x")).map_err(|_| "invalid hex address.")
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use crate::bip340::Bip340;
+	use sp_core::{sr25519, Pair};
+	use std::str::FromStr;
+
+	#[test]
+	pub fn bip340_to_string_works() {
+		let zero_key = Bip340::new([0u8; 32]);
+		let zero_key_str = zero_key.to_string();
+
+		assert_eq!(zero_key_str.len(), 66);
+		assert_eq!(
+			zero_key_str,
+			"0x0000000000000000000000000000000000000000000000000000000000000000"
+		);
+	}
+
+	#[test]
+	pub fn bip340_from_str_works() {
+		let zero_key_str = "0x0000000000000000000000000000000000000000000000000000000000000000";
+		let zero_key: Bip340 = Bip340::from_str(&zero_key_str).unwrap();
+		assert_eq!(zero_key, Bip340::new([0u8; 32]));
+	}
+
+	#[test]
+	pub fn bip340_serialize_works() {
+		let zero_key = Bip340::new([0u8; 32]);
+		let zero_key_str = serde_json::to_string(&zero_key).unwrap();
+
+		// contains leading and trailing ".
+		assert_eq!(zero_key_str.len(), 68);
+		assert_eq!(
+			zero_key_str,
+			"\"0x0000000000000000000000000000000000000000000000000000000000000000\""
+		);
+	}
+
+	#[test]
+	pub fn bip340_deserialize_works() {
+		let zero_key_str = "\"0x0000000000000000000000000000000000000000000000000000000000000000\"";
+		let zero_key: Bip340 = serde_json::from_str(&zero_key_str).unwrap();
+		assert_eq!(zero_key, Bip340::new([0u8; 32]));
+	}
+
+	#[test]
+	pub fn bip340_deserialize_without_prefix_works() {
+		let zero_key_str = "\"0000000000000000000000000000000000000000000000000000000000000000\"";
+		let zero_key: Bip340 = serde_json::from_str(&zero_key_str).unwrap();
+		assert_eq!(zero_key, Bip340::new([0u8; 32]));
+	}
+
+	#[test]
+	pub fn bip340_deserialize_alice_works() {
+		let alice_str = "\"0xd43593c715fdd31c61141abd04a99fd6822c8558854ccde39a5684e7a56da27d\"";
+		let alice: Bip340 = serde_json::from_str(alice_str).unwrap();
+		assert_eq!(
+			alice,
+			Bip340::from(sr25519::Pair::from_string_with_seed("//Alice", None).unwrap().0.public())
+		);
+	}
+}

primitives/core/src/lib.rs

@@ -16,6 +16,7 @@
 
 #![cfg_attr(not(feature = "std"), no_std)]
 
+pub mod bip340;
 pub mod bs58_verify;
 pub mod math;
 pub mod random_number_generator;

primitives/src/communities.rs

@@ -18,7 +18,7 @@ use crate::common::FromStr as CrateFromStr;
 use bs58;
 use codec::{Decode, Encode, MaxEncodedLen};
 use crc::{Crc, CRC_32_CKSUM};
-use ep_core::fixed::types::I64F64;
+use ep_core::{bip340::Bip340, fixed::types::I64F64};
 use geohash::GeoHash as GeohashGeneric;
 use scale_info::TypeInfo;
 use sp_core::RuntimeDebug;
@@ -235,7 +235,7 @@ impl Location {
 #[cfg_attr(feature = "serde_derive", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "serde_derive", serde(rename_all = "camelCase"))]
 pub enum AnnouncementSigner {
-	Bip340([u8; 32]),
+	Bip340(Bip340),
 }
 
 #[derive(