feature: allow signature to recover typed_data payloads (#2120)

* feature: allow signature to recover typed_data payloads

* fix: under feature flag and Changelog

* fix: undo accidental doc mangling

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 ### Unreleased
 
+- Add `Signature::recover_typed_data` [#2120](https://github.com/gakonst/ethers-rs/pull/2120)
 - Add `abi::encode_packed` [#2104](https://github.com/gakonst/ethers-rs/pull/2104)
 - Add support for custom JavaScript tracer to `debug_traceCall` and `debug_traceTransaction` [#2064](https://github.com/gakonst/ethers-rs/pull/2064)
 - Add a `Send` bound to the `IntoFuture` implementation of `ContractCall` [#2083](https://github.com/gakonst/ethers-rs/pull/2083)

ethers-core/src/types/signature.rs

@@ -69,6 +69,22 @@ impl fmt::Display for Signature {
     }
 }
 
+#[cfg(feature = "eip712")]
+impl Signature {
+    /// Recovers the ethereum address which was used to sign a given EIP712
+    /// typed data payload.
+    ///
+    /// Recovery signature data uses 'Electrum' notation, this means the `v`
+    /// value is expected to be either `27` or `28`.
+    pub fn recover_typed_data<T>(&self, payload: T) -> Result<Address, SignatureError>
+    where
+        T: super::transaction::eip712::Eip712,
+    {
+        let encoded = payload.encode_eip712().map_err(|_| SignatureError::RecoveryError)?;
+        self.recover(encoded)
+    }
+}
+
 impl Signature {
     /// Verifies that signature on `message` was produced by `address`
     pub fn verify<M, A>(&self, message: M, address: A) -> Result<(), SignatureError>