From 6ab78a00913642d33c9c6d9582683f763eda87e3 Mon Sep 17 00:00:00 2001
From: Gav Wood <gavin@ethcore.io>
Date: Wed, 10 Aug 2016 21:23:17 +0200
Subject: [PATCH] RPC for deriving address from phrase.

Fixed #1911
---
 rpc/src/v1/impls/ethcore.rs  | 11 +++++++++--
 rpc/src/v1/traits/ethcore.rs |  4 ++++
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/rpc/src/v1/impls/ethcore.rs b/rpc/src/v1/impls/ethcore.rs
index 117228fcc..93544aaf0 100644
--- a/rpc/src/v1/impls/ethcore.rs
+++ b/rpc/src/v1/impls/ethcore.rs
@@ -15,7 +15,7 @@
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.
 
 //! Ethcore-specific rpc implementation.
-use util::{RotatingLogger};
+use util::{RotatingLogger, KeyPair};
 use util::misc::version_data;
 use std::sync::{Arc, Weak};
 use std::collections::{BTreeMap};
@@ -24,7 +24,7 @@ use ethcore::client::{MiningBlockChainClient};
 use jsonrpc_core::*;
 use ethcore::miner::MinerService;
 use v1::traits::Ethcore;
-use v1::types::{Bytes, U256};
+use v1::types::{Bytes, U256, H160};
 use v1::helpers::{errors, SigningQueue, ConfirmationsQueue, NetworkSettings};
 use v1::helpers::params::expect_no_params;
 
@@ -173,4 +173,11 @@ impl<C, M> Ethcore for EthcoreClient<C, M> where M: MinerService + 'static, C: M
 
 		to_value(&random_phrase(12))
 	}
+
+	fn phrase_to_address(&self, params: Params) -> Result<Value, Error> {
+		try!(self.active());
+		from_params::<(String,)>(params).and_then(|(phrase,)|
+			to_value(&H160::from(KeyPair::from_phrase(&phrase).address()))
+		)
+	}
 }
diff --git a/rpc/src/v1/traits/ethcore.rs b/rpc/src/v1/traits/ethcore.rs
index 73411a584..2419c55dd 100644
--- a/rpc/src/v1/traits/ethcore.rs
+++ b/rpc/src/v1/traits/ethcore.rs
@@ -70,6 +70,9 @@ pub trait Ethcore: Sized + Send + Sync + 'static {
 	/// Returns a cryptographically random phrase sufficient for securely seeding a secret key.
 	fn generate_secret_phrase(&self, _: Params) -> Result<Value, Error>;
 
+	/// Returns whatever address would be derived from the given phrase if it were to seed a brainwallet.
+	fn phrase_to_address(&self, _: Params) -> Result<Value, Error>;
+
 	/// Should be used to convert object to io delegate.
 	fn to_delegate(self) -> IoDelegate<Self> {
 		let mut delegate = IoDelegate::new(Arc::new(self));
@@ -90,6 +93,7 @@ pub trait Ethcore: Sized + Send + Sync + 'static {
 		delegate.add_method("ethcore_gasPriceStatistics", Ethcore::gas_price_statistics);
 		delegate.add_method("ethcore_unsignedTransactionsCount", Ethcore::unsigned_transactions_count);
 		delegate.add_method("ethcore_generateSecretPhrase", Ethcore::generate_secret_phrase);
+		delegate.add_method("ethcore_phraseToAddress", Ethcore::phrase_to_address);
 
 		delegate
 	}