hkd32: Add built-in bip39::Mnemonic support

Adds integrated support for deriving the HKD32 key hierarchy from a
BIP39 Mnemonic phrase.

Uses the `tiny-bip39` crate, a (maintained) fork of the `bip39` crate.

Author: tony-iqlusion

Cargo.lock

@@ -40,6 +40,7 @@ This repository contains the following crates:
 |-------------------|----------------------------|-------------|
 | [canonical-path]  | ![][canonical-path-crate]  | Canonical filesystem path support |
 | [gaunt]           | ![][gaunt-crate]           | Minimalist HTTP library |
+| [hkd32]           | ![][hkd32-crate]           | HMAC-based Hierarchical Key Derivation |
 | [secrecy]         | ![][secrecy-crate]         | Simple secret-keeping library |
 | [subtle-encoding] | ![][subtle-encoding-crate] | Hex, Bech32, and Base64 in constant-time(ish) |
 | [tai64]           | ![][tai64-crate]           | TAI64(N) timestamp format |
@@ -85,6 +86,8 @@ without any additional terms or conditions.
 [canonical-path-crate]: https://img.shields.io/crates/v/canonical-path.svg
 [gaunt]: https://github.com/iqlusioninc/crates/tree/develop/gaunt
 [gaunt-crate]: https://img.shields.io/crates/v/gaunt.svg
+[hkd32]: https://github.com/iqlusioninc/crates/tree/develop/hkd32
+[hkd32-crate]: https://img.shields.io/crates/v/hkd32.svg
 [secrecy]: https://github.com/iqlusioninc/crates/tree/develop/secrecy
 [secrecy-crate]: https://img.shields.io/crates/v/secrecy.svg
 [subtle-encoding]: https://github.com/iqlusioninc/crates/tree/develop/subtle-encoding

README.md

@@ -23,6 +23,7 @@ travis-ci = { repository = "iqlusioninc/crates", branch = "develop" }
 getrandom = { version = "0.1", optional = true }
 hmac = { version = "0.7", default-features = false }
 sha2 = { version = "0.8", default-features = false }
+tiny-bip39 = { version = "0.6", default-features = false, optional = true }
 
 [dependencies.zeroize]
 version = "0.9"
@@ -33,3 +34,7 @@ features = ["zeroize_derive"]
 [features]
 default = ["alloc", "getrandom"]
 alloc = []
+mnemonic = ["tiny-bip39"]
+
+[package.metadata.docs.rs]
+all-features = true

hkd32/Cargo.toml

@@ -14,7 +14,8 @@ symmetric key derivation construction inspired by
 [BIP-0032: Hierarchical Deterministic Wallets][bip32].
 
 It can be used to deterministically derive a hierarchy of symmetric keys
-from initial keying material through repeated applications of the
+from initial keying material (or when the `mnemonic` feature is enabled,
+through a 24-word [BIP39] passphrase) by repeatedly applying the
 Hash-based Message Authentication Code (HMAC).
 
 This construction is specialized for deriving 32-byte (256-bit) keys from
@@ -63,3 +64,4 @@ without any additional terms or conditions.
 [//]: # (general links)
 
 [bip32]: https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki
+[bip39]: https://github.com/bitcoin/bips/blob/master/bip-0039.mediawiki