From 8bf03bb8ff334e0a0b2929c13a35b581f86af7b8 Mon Sep 17 00:00:00 2001
From: Gav Wood <gav@ethcore.io>
Date: Wed, 6 Jan 2016 13:53:23 +0100
Subject: [PATCH] Secure trie functions & structs.

---
 src/rlp/tests.rs      |  2 +-
 src/trie/mod.rs       |  4 ++++
 src/trie/triedbmut.rs | 24 ++++++++++++------------
 src/triehash.rs       | 35 +++++++++++++++++++++++++++++++++++
 4 files changed, 52 insertions(+), 13 deletions(-)

diff --git a/src/rlp/tests.rs b/src/rlp/tests.rs
index b4a60a3de..39af862ff 100644
--- a/src/rlp/tests.rs
+++ b/src/rlp/tests.rs
@@ -4,7 +4,7 @@ use self::json_tests::rlp as rlptest;
 use std::{fmt, cmp};
 use std::str::FromStr;
 use rlp;
-use rlp::{UntrustedRlp, RlpStream, Decodable, View, Stream, Encodable};
+use rlp::{UntrustedRlp, RlpStream, View, Stream};
 use uint::U256;
 
 #[test]
diff --git a/src/trie/mod.rs b/src/trie/mod.rs
index 4469926d5..1b5919bd4 100644
--- a/src/trie/mod.rs
+++ b/src/trie/mod.rs
@@ -4,8 +4,12 @@ pub mod journal;
 pub mod node;
 pub mod triedb;
 pub mod triedbmut;
+pub mod sectriedb;
+pub mod sectriedbmut;
 
 pub use self::trietraits::*;
 pub use self::standardmap::*;
 pub use self::triedbmut::*;
 pub use self::triedb::*;
+pub use self::sectriedbmut::*;
+pub use self::sectriedb::*;
diff --git a/src/trie/triedbmut.rs b/src/trie/triedbmut.rs
index 004912a4c..4c78e7667 100644
--- a/src/trie/triedbmut.rs
+++ b/src/trie/triedbmut.rs
@@ -9,18 +9,6 @@ use super::node::*;
 use super::journal::*;
 use super::trietraits::*;
 
-pub struct TrieDBMut<'db> {
-	db: &'db mut HashDB,
-	root: &'db mut H256,
-	pub hash_count: usize,
-}
-
-/// Option-like type allowing either a Node object passthrough or Bytes in the case of data alteration.
-enum MaybeChanged<'a> {
-	Same(Node<'a>),
-	Changed(Bytes),
-}
-
 /// A `Trie` implementation using a generic `HashDB` backing database.
 /// 
 /// Use it as a `Trie` trait object. You can use `db()` to get the backing database object, `keys`
@@ -52,6 +40,18 @@ enum MaybeChanged<'a> {
 ///   assert!(t.db_items_remaining().is_empty());
 /// }
 /// ```
+pub struct TrieDBMut<'db> {
+	db: &'db mut HashDB,
+	root: &'db mut H256,
+	pub hash_count: usize,
+}
+
+/// Option-like type allowing either a Node object passthrough or Bytes in the case of data alteration.
+enum MaybeChanged<'a> {
+	Same(Node<'a>),
+	Changed(Bytes),
+}
+
 impl<'db> TrieDBMut<'db> {
 	/// Create a new trie with the backing database `db` and empty `root`
 	/// Initialise to the state entailed by the genesis block.
diff --git a/src/triehash.rs b/src/triehash.rs
index 67ffcc666..74900971c 100644
--- a/src/triehash.rs
+++ b/src/triehash.rs
@@ -77,6 +77,41 @@ pub fn trie_root(input: Vec<(Vec<u8>, Vec<u8>)>) -> H256 {
 	gen_trie_root(gen_input)
 }
 
+/// Generates a key-hashed (secure) trie root hash for a vector of key-values.
+///
+/// ```rust
+/// extern crate ethcore_util as util;
+/// use std::str::FromStr;
+/// use util::triehash::*;
+/// use util::hash::*;
+/// 
+/// fn main() {
+/// 	let v = vec![
+/// 		(From::from("doe"), From::from("reindeer")),
+/// 		(From::from("dog"), From::from("puppy")),
+/// 		(From::from("dogglesworth"), From::from("cat")),
+/// 	];
+///
+/// 	let root = "d4cd937e4a4368d7931a9cf51686b7e10abb3dce38a39000fd7902a092b64585";
+/// 	assert_eq!(sec_trie_root(v), H256::from_str(root).unwrap());
+/// }
+/// ```
+pub fn sec_trie_root(input: Vec<(Vec<u8>, Vec<u8>)>) -> H256 {
+	let gen_input = input
+		// first put elements into btree to sort them and to remove duplicates
+		.into_iter()
+		.fold(BTreeMap::new(), | mut acc, (k, v) | {
+			acc.insert(k.sha3().to_vec(), v);
+			acc
+		})
+		// then move them to a vector
+		.into_iter()
+		.map(|(k, v)| (as_nibbles(&k), v) )
+		.collect();
+
+	gen_trie_root(gen_input)
+}
+
 fn gen_trie_root(input: Vec<(Vec<u8>, Vec<u8>)>) -> H256 {
 	let mut stream = RlpStream::new();
 	hash256rlp(&input, 0, &mut stream);