Remove secp256k1 from WASM build (#5187)

* Remove `secp256k1` from WASM build

* Bring back full public key parse on native

* Add extra method to create from a full public key

substrate/primitives/core/Cargo.toml

@@ -33,7 +33,6 @@ parking_lot = { version = "0.10.0", optional = true }
 sp-debug-derive = { version = "2.0.0-alpha.2", path = "../debug-derive" }
 sp-externalities = { version = "0.8.0-alpha.2", optional = true, path = "../externalities" }
 sp-storage = { version = "2.0.0-alpha.2", default-features = false, path = "../storage" }
-libsecp256k1 = { version = "0.3.2", default-features = false, features = ["hmac"] }
 parity-util-mem = { version = "0.5.1", default-features = false, features = ["primitive-types"] }
 
 # full crypto
@@ -44,6 +43,7 @@ schnorrkel = { version = "0.8.5", features = ["preaudit_deprecated", "u64_backen
 sha2 = { version = "0.8.0", default-features = false, optional = true }
 hex = { version = "0.4", default-features = false, optional = true }
 twox-hash = { version = "1.5.0", default-features = false, optional = true }
+libsecp256k1 = { version = "0.3.2", default-features = false, features = ["hmac"], optional = true }
 
 sp-runtime-interface = { version = "2.0.0-alpha.2", default-features = false, path = "../runtime-interface" }
 
@@ -116,5 +116,6 @@ full_crypto = [
 	"hex",
 	"sha2",
 	"twox-hash",
+	"libsecp256k1",
 	"sp-runtime-interface/disable_target_static_assertions",
 ]

substrate/primitives/core/src/ecdsa.rs

@@ -92,6 +92,17 @@ impl Public {
 	pub fn from_raw(data: [u8; 33]) -> Self {
 		Self(data)
 	}
+
+	/// Create a new instance from the given full public key.
+	///
+	/// This will convert the full public key into the compressed format.
+	#[cfg(feature = "std")]
+	pub fn from_full(full: &[u8]) -> Result<Self, ()> {
+		secp256k1::PublicKey::parse_slice(full, None)
+			.map(|k| k.serialize_compressed())
+			.map(Self)
+			.map_err(|_| ())
+	}
 }
 
 impl TraitPublic for Public {
@@ -133,10 +144,8 @@ impl sp_std::convert::TryFrom<&[u8]> for Public {
 		if data.len() == 33 {
 			Ok(Self::from_slice(data))
 		} else {
-			secp256k1::PublicKey::parse_slice(data, None)
+
-				.map(|k| k.serialize_compressed())
+			Err(())
-				.map(Self)
-				.map_err(|_| ())
 		}
 	}
 }
@@ -544,7 +553,7 @@ mod test {
 		let public = pair.public();
 		assert_eq!(
 			public,
-			Public::try_from(
+			Public::from_full(
 				&hex!("8db55b05db86c0b1786ca49f095d76344c9e6056b2f02701a7e7f3c20aabfd913ebbe148dd17c56551a52952371071a6c604b3f3abe8f2c8fa742158ea6dd7d4")[..],
 			).unwrap(),
 		);
@@ -564,7 +573,7 @@ mod test {
 		let public = pair.public();
 		assert_eq!(
 			public,
-			Public::try_from(
+			Public::from_full(
 				&hex!("8db55b05db86c0b1786ca49f095d76344c9e6056b2f02701a7e7f3c20aabfd913ebbe148dd17c56551a52952371071a6c604b3f3abe8f2c8fa742158ea6dd7d4")[..],
 			).unwrap(),
 		);
@@ -591,7 +600,7 @@ mod test {
 		let public = pair.public();
 		assert_eq!(
 			public,
-			Public::try_from(
+			Public::from_full(
 				&hex!("5676109c54b9a16d271abeb4954316a40a32bcce023ac14c8e26e958aa68fba995840f3de562156558efbfdac3f16af0065e5f66795f4dd8262a228ef8c6d813")[..],
 			).unwrap(),
 		);