From 41abdbcaef73e715a1307b514b33453202e827ba Mon Sep 17 00:00:00 2001
From: Brian Warner <warner@lothar.com>
Date: Wed, 5 Feb 2020 13:11:38 -0800
Subject: [PATCH] zeroize Key and derived keys upon drop

refs #63
---
 Cargo.toml          | 1 +
 src/core/events.rs  | 4 +++-
 src/core/receive.rs | 8 ++++++--
 src/core/send.rs    | 7 +++++--
 4 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index cd8f7200..b246e70a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -29,6 +29,7 @@ hex = "0.4"
 rand = "0.7"
 regex = "1.0"
 log = "0.4"
+zeroize = { version = "1.1", features = ["zeroize_derive"] }
 
 # for "io_blocking" feature
 ws = { version = "0.9", optional = true }
diff --git a/src/core/events.rs b/src/core/events.rs
index b9c1c756..1c96c30e 100644
--- a/src/core/events.rs
+++ b/src/core/events.rs
@@ -10,6 +10,7 @@ use super::api::{APIAction, IOAction, Mood};
 use super::timing::TimingLogEvent;
 use super::util::maybe_utf8;
 use crate::core::util::random_bytes;
+use zeroize::Zeroize;
 
 pub use super::wordlist::Wordlist;
 
@@ -23,7 +24,8 @@ impl<'a> From<&'a str> for AppID {
     }
 }
 
-#[derive(PartialEq, Eq, Clone)]
+#[derive(PartialEq, Eq, Clone, Zeroize)]
+#[zeroize(drop)]
 pub struct Key(pub Vec<u8>);
 impl Deref for Key {
     type Target = Vec<u8>;
diff --git a/src/core/receive.rs b/src/core/receive.rs
index 212b2877..f17898ec 100644
--- a/src/core/receive.rs
+++ b/src/core/receive.rs
@@ -1,6 +1,8 @@
 use super::events::{Events, Key, Phase, TheirSide};
 use super::key;
 use log::trace;
+use zeroize::Zeroize;
+
 // we process these
 use super::events::ReceiveEvent;
 // we emit these
@@ -104,8 +106,10 @@ impl ReceiveMachine {
         phase: &Phase,
         body: &[u8],
     ) -> Option<Vec<u8>> {
-        let data_key = key::derive_phase_key(&side, &key, &phase);
-        key::decrypt_data(&data_key, body)
+        let mut data_key = key::derive_phase_key(&side, &key, &phase);
+        let data = key::decrypt_data(&data_key, body);
+        data_key.zeroize();
+        data
     }
 }
 
diff --git a/src/core/send.rs b/src/core/send.rs
index 3882db9d..59331238 100644
--- a/src/core/send.rs
+++ b/src/core/send.rs
@@ -1,6 +1,7 @@
 use super::events::{Events, Key, MySide, Phase};
 use super::key;
 use log::trace;
+use zeroize::Zeroize;
 // we process these
 use super::events::SendEvent;
 // we emit these
@@ -42,10 +43,11 @@ impl SendMachine {
                 match event {
                     GotVerifiedKey(ref key) => {
                         for (phase, plaintext) in self.queue.drain(..) {
-                            let data_key =
+                            let mut data_key =
                                 key::derive_phase_key(&self.side, &key, &phase);
                             let (_nonce, encrypted) =
                                 key::encrypt_data(&data_key, &plaintext);
+                            data_key.zeroize();
                             actions.push(M_AddMessage(phase, encrypted));
                         }
                         S1HaveVerifiedKey(key.clone())
@@ -61,10 +63,11 @@ impl SendMachine {
             S1HaveVerifiedKey(ref key) => match event {
                 GotVerifiedKey(_) => panic!(),
                 Send(phase, plaintext) => {
-                    let data_key =
+                    let mut data_key =
                         key::derive_phase_key(&self.side, &key, &phase);
                     let (_nonce, encrypted) =
                         key::encrypt_data(&data_key, &plaintext);
+                    data_key.zeroize();
                     actions.push(M_AddMessage(phase, encrypted));
                     S1HaveVerifiedKey(key.clone())
                 }