hkd32: Merge code from tiny-bip39

All of the `bip39` code is high-sensitivity in that it deals with master
derivation passwords for secret keys. Unfortunately, the `bip39` crate
seems abandoned, which is not a good state for such a high-sensitivity
crate to be in.

This commit merges in the code from `tiny-bip39` as of the following
git commit bumping the version to v0.6.2:

> Version bump

maciejhirsz/tiny-bip39@dfcb9c9

This commit makes no other changes to the incorporated files, and they
have not been "wired up" to the rest of `hkd32` yet.

Author: tony-iqlusion

hkd32/Cargo.toml

@@ -14,7 +14,7 @@ homepage    = "https://github.com/iqlusioninc/crates/"
 repository  = "https://github.com/iqlusioninc/crates/tree/develop/hkd32"
 readme      = "README.md"
 categories  = ["cryptography", "no-std"]
-keywords    = ["bip32", "derivation", "hd", "hmac", "key"]
+keywords    = ["crypto", "bip32", "bip39", "derivation", "mnemonic"]
 
 [badges]
 maintenance = { status = "passively-maintained" }

hkd32/LICENSE-MIT

@@ -0,0 +1,19 @@
+The MIT License (MIT)
+Copyright (c) 2017-2018 Stephen Oliver
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

hkd32/README.md

@@ -4,7 +4,7 @@
 [![Crate][crate-image]][crate-link]
 [![Docs][docs-image]][docs-link]
 [![Apache 2.0 Licensed][license-image]][license-link]
-![Rust 1.36+][rustc-image]
+![MSRV][rustc-image]
 [![Build Status][build-image]][build-link]
 [![Gitter Chat][gitter-image]][gitter-link]
 
@@ -26,17 +26,14 @@ an initial 32-bytes of input key material.
 
 Copyright © 2019 iqlusion
 
-Licensed under the Apache License, Version 2.0 (the "License");
-you may not use this file except in compliance with the License.
-You may obtain a copy of the License at
+Includes code from the `bip39` crate. Copyright © 2017-2018 Stephen Oliver,
+with contributions by Maciej Hirsz.
 
-    https://www.apache.org/licenses/LICENSE-2.0
+**hkd32** is distributed under the terms of either the MIT license
+or the Apache License (Version 2.0), at your option.
 
-Unless required by applicable law or agreed to in writing, software
-distributed under the License is distributed on an "AS IS" BASIS,
-WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-See the License for the specific language governing permissions and
-limitations under the License.
+See [LICENSE] (Apache License, Version 2.0) file in the `iqlusioninc/crates`
+toplevel directory of this repository or [LICENSE-MIT] for details.
 
 ## Contribution
 
@@ -62,3 +59,5 @@ without any additional terms or conditions.
 
 [bip32]: https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki
 [bip39]: https://github.com/bitcoin/bips/blob/master/bip-0039.mediawiki
+[LICENSE]: https://github.com/iqlusioninc/crates/blob/develop/LICENSE
+[LICENSE-MIT]: https://github.com/iqlusioninc/crates/blob/develop/hkd32/LICENSE-MIT

hkd32/src/mnemonic/crypto.rs

@@ -0,0 +1,43 @@
+//! These are internal helper functions used when creating a new [`Mnemonic`][Mnemonic], and when turning a [`Mnemonic`][Mnemonic]
+//! into a [`Seed`][Seed].
+//!
+//! [Mnemonic]: ../mnemonic/struct.Mnemonic.html
+//! [Seed]: ../seed/struct.Seed.html
+//!
+
+extern crate rand;
+use self::rand::{ thread_rng, RngCore };
+use sha2::Digest;
+use hmac::Hmac;
+
+const PBKDF2_ROUNDS: usize = 2048;
+const PBKDF2_BYTES: usize = 64;
+
+/// SHA256 helper function, internal to the crate
+///
+pub(crate) fn sha256_first_byte(input: &[u8]) -> u8 {
+    sha2::Sha256::digest(input).as_ref()[0]
+}
+
+/// Random byte generator, used to create new mnemonics
+///
+pub(crate) fn gen_random_bytes(byte_length: usize) -> Vec<u8> {
+    let mut rng = thread_rng();
+    let mut bytes = vec![0u8; byte_length];
+
+    rng.fill_bytes(&mut bytes);
+
+    bytes
+}
+/// PBKDF2 helper, used to generate [`Seed`][Seed] from [`Mnemonic`][Mnemonic]
+///
+/// [Mnemonic]: ../mnemonic/struct.Mnemonic.html
+/// [Seed]: ../seed/struct.Seed.html
+///
+pub(crate) fn pbkdf2(input: &[u8], salt: &str) -> Vec<u8> {
+    let mut seed = vec![0u8; PBKDF2_BYTES];
+
+    pbkdf2::pbkdf2::<Hmac<sha2::Sha512>>(input, salt.as_bytes(), PBKDF2_ROUNDS, &mut seed);
+
+    seed
+}

hkd32/src/mnemonic/error.rs

@@ -0,0 +1,15 @@
+use mnemonic_type::MnemonicType;
+
+#[derive(Debug, Fail)]
+pub enum ErrorKind {
+	#[fail(display = "invalid checksum")]
+	InvalidChecksum,
+	#[fail(display = "invalid word in phrase")]
+	InvalidWord,
+	#[fail(display = "invalid keysize: {}", _0)]
+	InvalidKeysize(usize),
+	#[fail(display = "invalid number of words in phrase: {}", _0)]
+	InvalidWordLength(usize),
+	#[fail(display = "invalid entropy length {}bits for mnemonic type {:?}", _0, _1)]
+	InvalidEntropyLength(usize, MnemonicType),
+}