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Arbitrary labels for extended keys (u32, H256 built-in) (#4438)

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* extend derivatino to arbitrary labels

* fix review

* fix more obsolete comments

* hard test for h256

* fix using only 4 bytes from hash
This commit is contained in:
Nikolay Volf 2017-02-09 18:44:28 +03:00 committed by Gav Wood
parent 3da3e8453b
commit fea76c07f0
1 changed files with 112 additions and 42 deletions
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154
ethkey/src/extended.rs
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@ -21,6 +21,53 @@ use Public;
use bigint::hash::{H256, FixedHash};
pub use self::derivation::Error as DerivationError;
/// Represents label that can be stored as a part of key derivation
pub trait Label {
/// Length of the data that label occupies
fn len() -> usize;
/// Store label data to the key derivation sequence
/// Must not use more than `len()` bytes from slice
fn store(&self, target: &mut [u8]);
}
impl Label for u32 {
fn len() -> usize { 4 }
fn store(&self, target: &mut [u8]) {
use byteorder::{BigEndian, ByteOrder};
BigEndian::write_u32(&mut target[0..4], *self);
}
}
/// Key derivation over generic label `T`
pub enum Derivation<T: Label> {
/// Soft key derivation (allow proof of parent)
Soft(T),
/// Hard key derivation (does not allow proof of parent)
Hard(T),
}
impl From<u32> for Derivation<u32> {
fn from(index: u32) -> Self {
if index < (2 << 30) {
Derivation::Soft(index)
}
else {
Derivation::Hard(index)
}
}
}
impl Label for H256 {
fn len() -> usize { 32 }
fn store(&self, target: &mut [u8]) {
self.copy_to(&mut target[0..32]);
}
}
/// Extended secret key, allows deterministic derivation of subsequent keys.
pub struct ExtendedSecret {
secret: Secret,
@ -49,7 +96,7 @@ impl ExtendedSecret {
}
/// Derive new private key
pub fn derive(&self, index: u32) -> ExtendedSecret {
pub fn derive<T>(&self, index: Derivation<T>) -> ExtendedSecret where T: Label {
let (derived_key, next_chain_code) = derivation::private(*self.secret, self.chain_code, index);
let derived_secret = Secret::from_slice(&*derived_key)
@ -88,7 +135,7 @@ impl ExtendedPublic {
/// Derive new public key
/// Operation is defined only for index belongs [0..2^31)
pub fn derive(&self, index: u32) -> Result<Self, DerivationError> {
pub fn derive<T>(&self, index: Derivation<T>) -> Result<Self, DerivationError> where T: Label {
let (derived_key, next_chain_code) = derivation::public(self.public, self.chain_code, index)?;
Ok(ExtendedPublic::new(derived_key, next_chain_code))
}
@ -147,7 +194,7 @@ impl ExtendedKeyPair {
&self.public
}
pub fn derive(&self, index: u32) -> Result<Self, DerivationError> {
pub fn derive<T>(&self, index: Derivation<T>) -> Result<Self, DerivationError> where T: Label {
let derived = self.secret.derive(index);
Ok(ExtendedKeyPair {
@ -167,11 +214,11 @@ mod derivation {
use rcrypto::sha2::Sha512;
use bigint::hash::{H512, H256, FixedHash};
use bigint::prelude::{U256, U512, Uint};
use byteorder::{BigEndian, ByteOrder};
use secp256k1;
use secp256k1::key::{SecretKey, PublicKey};
use SECP256K1;
use keccak;
use super::{Label, Derivation};
#[derive(Debug)]
pub enum Error {
@ -183,20 +230,18 @@ mod derivation {
// Deterministic derivation of the key using secp256k1 elliptic curve.
// Derivation can be either hardened or not.
// For hardened derivation, pass index at least 2^31
// For hardened derivation, pass u32 index at least 2^31 or custom Derivation::Hard(T) enum
//
// Can panic if passed `private_key` is not a valid secp256k1 private key
// (outside of (0..curve_n()]) field
pub fn private(private_key: H256, chain_code: H256, index: u32) -> (H256, H256) {
if index < (2 << 30) {
private_soft(private_key, chain_code, index)
}
else {
private_hard(private_key, chain_code, index)
pub fn private<T>(private_key: H256, chain_code: H256, index: Derivation<T>) -> (H256, H256) where T: Label {
match index {
Derivation::Soft(index) => private_soft(private_key, chain_code, index),
Derivation::Hard(index) => private_hard(private_key, chain_code, index),
}
}
fn hmac_pair(data: [u8; 37], private_key: H256, chain_code: H256) -> (H256, H256) {
fn hmac_pair(data: &[u8], private_key: H256, chain_code: H256) -> (H256, H256) {
let private: U256 = private_key.into();
// produces 512-bit derived hmac (I)
@ -216,8 +261,8 @@ mod derivation {
// Can panic if passed `private_key` is not a valid secp256k1 private key
// (outside of (0..curve_n()]) field
fn private_soft(private_key: H256, chain_code: H256, index: u32) -> (H256, H256) {
let mut data = [0u8; 37];
fn private_soft<T>(private_key: H256, chain_code: H256, index: T) -> (H256, H256) where T: Label {
let mut data = vec![0u8; 33 + T::len()];
let sec_private = SecretKey::from_slice(&SECP256K1, &*private_key)
.expect("Caller should provide valid private key");
@ -226,26 +271,26 @@ mod derivation {
let public_serialized = sec_public.serialize_vec(&SECP256K1, true);
// curve point (compressed public key) -- index
// 0.33 -- 33..37
// 0.33 -- 33..end
data[0..33].copy_from_slice(&public_serialized);
BigEndian::write_u32(&mut data[33..37], index);
index.store(&mut data[33..]);
hmac_pair(data, private_key, chain_code)
hmac_pair(&data, private_key, chain_code)
}
// Deterministic derivation of the key using secp256k1 elliptic curve
// This is hardened derivation and does not allow to associate
// corresponding public keys of the original and derived private keys
fn private_hard(private_key: H256, chain_code: H256, index: u32) -> (H256, H256) {
let mut data = [0u8; 37];
fn private_hard<T>(private_key: H256, chain_code: H256, index: T) -> (H256, H256) where T: Label {
let mut data: Vec<u8> = vec![0u8; 33 + T::len()];
let private: U256 = private_key.into();
// 0x00 (padding) -- private_key -- index
// 0 -- 1..33 -- 33..37
// 0 -- 1..33 -- 33..end
private.to_big_endian(&mut data[1..33]);
BigEndian::write_u32(&mut data[33..37], index);
index.store(&mut data[33..(33 + T::len())]);
hmac_pair(data, private_key, chain_code)
hmac_pair(&data, private_key, chain_code)
}
fn private_add(k1: U256, k2: U256) -> U256 {
@ -266,11 +311,11 @@ mod derivation {
H256::from_slice(&secp256k1::constants::CURVE_ORDER).into()
}
pub fn public(public_key: H512, chain_code: H256, index: u32) -> Result<(H512, H256), Error> {
if index >= (2 << 30) {
// public derivation is only defined on 'soft' index space [0..2^31)
return Err(Error::InvalidHardenedUse)
}
pub fn public<T>(public_key: H512, chain_code: H256, derivation: Derivation<T>) -> Result<(H512, H256), Error> where T: Label {
let index = match derivation {
Derivation::Soft(index) => index,
Derivation::Hard(_) => { return Err(Error::InvalidHardenedUse); }
};
let mut public_sec_raw = [0u8; 65];
public_sec_raw[0] = 4;
@ -278,11 +323,11 @@ mod derivation {
let public_sec = PublicKey::from_slice(&SECP256K1, &public_sec_raw).map_err(|_| Error::InvalidPoint)?;
let public_serialized = public_sec.serialize_vec(&SECP256K1, true);
let mut data = [0u8; 37];
let mut data = vec![0u8; 33 + T::len()];
// curve point (compressed public key) -- index
// 0.33 -- 33..37
// 0.33 -- 33..end
data[0..33].copy_from_slice(&public_serialized);
BigEndian::write_u32(&mut data[33..37], index);
index.store(&mut data[33..(33 + T::len())]);
// HMAC512SHA produces [derived private(256); new chain code(256)]
let mut hmac = Hmac::new(Sha512::new(), &*chain_code);
@ -351,7 +396,7 @@ mod tests {
use secret::Secret;
use std::str::FromStr;
use bigint::hash::{H128, H256};
use super::derivation;
use super::{derivation, Derivation};
fn master_chain_basic() -> (H256, H256) {
let seed = H128::from_str("000102030405060708090a0b0c0d0e0f")
@ -375,23 +420,48 @@ mod tests {
// hardened
assert_eq!(&**extended_secret.secret(), &*secret);
assert_eq!(&**extended_secret.derive(2147483648).secret(), &"0927453daed47839608e414a3738dfad10aed17c459bbd9ab53f89b026c834b6".into());
assert_eq!(&**extended_secret.derive(2147483649).secret(), &"44238b6a29c6dcbe9b401364141ba11e2198c289a5fed243a1c11af35c19dc0f".into());
assert_eq!(&**extended_secret.derive(2147483648.into()).secret(), &"0927453daed47839608e414a3738dfad10aed17c459bbd9ab53f89b026c834b6".into());
assert_eq!(&**extended_secret.derive(2147483649.into()).secret(), &"44238b6a29c6dcbe9b401364141ba11e2198c289a5fed243a1c11af35c19dc0f".into());
// normal
assert_eq!(&**extended_secret.derive(0).secret(), &"bf6a74e3f7b36fc4c96a1e12f31abc817f9f5904f5a8fc27713163d1f0b713f6".into());
assert_eq!(&**extended_secret.derive(1).secret(), &"bd4fca9eb1f9c201e9448c1eecd66e302d68d4d313ce895b8c134f512205c1bc".into());
assert_eq!(&**extended_secret.derive(2).secret(), &"86932b542d6cab4d9c65490c7ef502d89ecc0e2a5f4852157649e3251e2a3268".into());
assert_eq!(&**extended_secret.derive(0.into()).secret(), &"bf6a74e3f7b36fc4c96a1e12f31abc817f9f5904f5a8fc27713163d1f0b713f6".into());
assert_eq!(&**extended_secret.derive(1.into()).secret(), &"bd4fca9eb1f9c201e9448c1eecd66e302d68d4d313ce895b8c134f512205c1bc".into());
assert_eq!(&**extended_secret.derive(2.into()).secret(), &"86932b542d6cab4d9c65490c7ef502d89ecc0e2a5f4852157649e3251e2a3268".into());
let extended_public = ExtendedPublic::from_secret(&extended_secret).expect("Extended public should be created");
let derived_public = extended_public.derive(0).expect("First derivation of public should succeed");
let derived_public = extended_public.derive(0.into()).expect("First derivation of public should succeed");
assert_eq!(&*derived_public.public(), &"f7b3244c96688f92372bfd4def26dc4151529747bab9f188a4ad34e141d47bd66522ff048bc6f19a0a4429b04318b1a8796c000265b4fa200dae5f6dda92dd94".into());
let keypair = ExtendedKeyPair::with_secret(
Secret::from_str("a100df7a048e50ed308ea696dc600215098141cb391e9527329df289f9383f65").unwrap(),
064.into(),
);
assert_eq!(&**keypair.derive(2147483648).expect("Derivation of keypair should succeed").secret().secret(), &"edef54414c03196557cf73774bc97a645c9a1df2164ed34f0c2a78d1375a930c".into());
assert_eq!(&**keypair.derive(2147483648u32.into()).expect("Derivation of keypair should succeed").secret().secret(), &"edef54414c03196557cf73774bc97a645c9a1df2164ed34f0c2a78d1375a930c".into());
}
#[test]
fn h256_soft_match() {
let secret = Secret::from_str("a100df7a048e50ed308ea696dc600215098141cb391e9527329df289f9383f65").unwrap();
let derivation_secret = H256::from_str("51eaf04f9dbbc1417dc97e789edd0c37ecda88bac490434e367ea81b71b7b015").unwrap();
let extended_secret = ExtendedSecret::with_code(secret.clone(), 0u64.into());
let extended_public = ExtendedPublic::from_secret(&extended_secret).expect("Extended public should be created");
let derived_secret0 = extended_secret.derive(Derivation::Soft(derivation_secret));
let derived_public0 = extended_public.derive(Derivation::Soft(derivation_secret)).expect("First derivation of public should succeed");
let public_from_secret0 = ExtendedPublic::from_secret(&derived_secret0).expect("Extended public should be created");
assert_eq!(public_from_secret0.public(), derived_public0.public());
}
#[test]
fn h256_hard() {
let secret = Secret::from_str("a100df7a048e50ed308ea696dc600215098141cb391e9527329df289f9383f65").unwrap();
let derivation_secret = H256::from_str("51eaf04f9dbbc1417dc97e789edd0c37ecda88bac490434e367ea81b71b7b015").unwrap();
let extended_secret = ExtendedSecret::with_code(secret.clone(), 1u64.into());
assert_eq!(&**extended_secret.derive(Derivation::Hard(derivation_secret)).secret(), &"2bc2d696fb744d77ff813b4a1ef0ad64e1e5188b622c54ba917acc5ebc7c5486".into());
}
#[test]
@ -400,8 +470,8 @@ mod tests {
let extended_secret = ExtendedSecret::with_code(secret.clone(), 1.into());
let extended_public = ExtendedPublic::from_secret(&extended_secret).expect("Extended public should be created");
let derived_secret0 = extended_secret.derive(0);
let derived_public0 = extended_public.derive(0).expect("First derivation of public should succeed");
let derived_secret0 = extended_secret.derive(0.into());
let derived_public0 = extended_public.derive(0.into()).expect("First derivation of public should succeed");
let public_from_secret0 = ExtendedPublic::from_secret(&derived_secret0).expect("Extended public should be created");
@ -429,7 +499,7 @@ mod tests {
/// xprv9uHRZZhk6KAJC1avXpDAp4MDc3sQKNxDiPvvkX8Br5ngLNv1TxvUxt4cV1rGL5hj6KCesnDYUhd7oWgT11eZG7XnxHrnYeSvkzY7d2bhkJ7
/// H(0)
test_extended(
|secret| secret.derive(2147483648),
|secret| secret.derive(2147483648.into()),
H256::from_str("edb2e14f9ee77d26dd93b4ecede8d16ed408ce149b6cd80b0715a2d911a0afea")
.expect("Private should be decoded ok")
);
@ -440,7 +510,7 @@ mod tests {
/// xprv9wTYmMFdV23N2TdNG573QoEsfRrWKQgWeibmLntzniatZvR9BmLnvSxqu53Kw1UmYPxLgboyZQaXwTCg8MSY3H2EU4pWcQDnRnrVA1xe8fs
/// H(0)/1
test_extended(
|secret| secret.derive(2147483648).derive(1),
|secret| secret.derive(2147483648.into()).derive(1.into()),
H256::from_str("3c6cb8d0f6a264c91ea8b5030fadaa8e538b020f0a387421a12de9319dc93368")
.expect("Private should be decoded ok")
);