Add Password type

Password is a newtype for String that zeros out memory when dropped.

Author: kseo

Cargo.lock

@@ -15,6 +15,7 @@ heapsize = "0.4"
 rlp = { path = "../util/rlp" }
 secp256k1 = { path = "../util/secp256k1" }
 serde = "1.0"
+serde_derive = "1.0"
 serde_json = "1.0"
 
 [features]

key/Cargo.toml

@@ -26,6 +26,8 @@ extern crate rustc_hex;
 extern crate rustc_serialize;
 extern crate secp256k1;
 extern crate serde;
+#[macro_use]
+extern crate serde_derive;
 extern crate serde_json;
 
 mod address;
@@ -35,6 +37,7 @@ mod error;
 mod exchange;
 mod keypair;
 mod network;
+mod password;
 mod private;
 mod random;
 #[cfg(feature = "schnorr")]
@@ -50,6 +53,7 @@ pub use error::Error;
 pub use exchange::exchange;
 pub use keypair::{public_to_address, KeyPair};
 pub use network::Network;
+pub use password::Password;
 use primitives::{H160, H256, H512};
 pub use private::Private;
 pub use random::Random;

key/src/lib.rs

@@ -0,0 +1,49 @@
+// Copyright 2018 Kodebox, Inc.
+// This file is part of CodeChain.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+use std::{fmt, ptr};
+
+#[derive(Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct Password(String);
+
+impl fmt::Debug for Password {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "Password(******)")
+    }
+}
+
+// Custom drop impl to zero out memory.
+impl Drop for Password {
+    fn drop(&mut self) {
+        unsafe {
+            for byte_ref in self.0.as_mut_vec() {
+                ptr::write_volatile(byte_ref, 0)
+            }
+        }
+    }
+}
+
+impl From<String> for Password {
+    fn from(s: String) -> Password {
+        Password(s)
+    }
+}
+
+impl<'a> From<&'a str> for Password {
+    fn from(s: &'a str) -> Password {
+        Password::from(String::from(s))
+    }
+}