diff --git a/src/util/bip32.rs b/src/util/bip32.rs index 78c8e9f3..9926f8a2 100644 --- a/src/util/bip32.rs +++ b/src/util/bip32.rs @@ -90,18 +90,62 @@ pub struct ExtendedPubKey { /// A child number for a derived key #[derive(Copy, Clone, PartialEq, Eq, Debug)] pub enum ChildNumber { - /// Non-hardened key, within [0, 2^31 - 1] - Normal(u32), - /// Hardened key index, within [2^31, 2^32 - 1] - Hardened(u32), + /// Non-hardened key + Normal { + /// Key index, within [0, 2^31 - 1] + index: u32 + }, + /// Hardened key + Hardened { + /// Key index, within [0, 2^31 - 1] + index: u32 + }, +} + +impl ChildNumber { + /// Create a [`Normal`] from an index, panics if the index is not within + /// [0, 2^31 - 1]. + /// + /// [`Normal`]: #variant.Normal + pub fn from_normal_idx(index: u32) -> Self { + assert_eq!(index & (1 << 31), 0, "ChildNumber indices have to be within [0, 2^31 - 1], is: {}", index); + ChildNumber::Normal { index: index } + } + + /// Create a [`Hardened`] from an index, panics if the index is not within + /// [0, 2^31 - 1]. + /// + /// [`Hardened`]: #variant.Hardened + pub fn from_hardened_idx(index: u32) -> Self { + assert_eq!(index & (1 << 31), 0, "ChildNumber indices have to be within [0, 2^31 - 1], is: {}", index); + ChildNumber::Hardened { index: index } + } + + /// Returns `true` if the child number is a [`Normal`] value. + /// + /// [`Normal`]: #variant.Normal + pub fn is_normal(&self) -> bool { + !self.is_hardened() + } + + /// Returns `true` if the child number is a [`Hardened`] value. + /// + /// [`Hardened`]: #variant.Hardened + pub fn is_hardened(&self) -> bool { + match *self { + ChildNumber::Hardened {..} => true, + ChildNumber::Normal {..} => false, + } + } + } impl From for ChildNumber { - fn from(index: u32) -> Self { - if index & (1 << 31) != 0 { - ChildNumber::Hardened(index) + fn from(number: u32) -> Self { + if number & (1 << 31) != 0 { + ChildNumber::Hardened { index: number ^ (1 << 31) } } else { - ChildNumber::Normal(index) + ChildNumber::Normal { index: number } } } } @@ -109,8 +153,8 @@ impl From for ChildNumber { impl From for u32 { fn from(cnum: ChildNumber) -> Self { match cnum { - ChildNumber::Normal(index) => index, - ChildNumber::Hardened(index) => index, + ChildNumber::Normal { index } => index, + ChildNumber::Hardened { index } => index | (1 << 31), } } } @@ -118,31 +162,23 @@ impl From for u32 { impl fmt::Display for ChildNumber { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { match *self { - ChildNumber::Hardened(n) => write!(f, "{}h", n), - ChildNumber::Normal(n) => write!(f, "{}", n) + ChildNumber::Hardened { index } => write!(f, "{}'", index), + ChildNumber::Normal { index } => write!(f, "{}", index), } } } impl Serialize for ChildNumber { - fn serialize(&self, s: &mut S) -> Result<(), S::Error> - where S: Serializer { - match *self { - ChildNumber::Hardened(n) => (n + (1 << 31)).serialize(s), - ChildNumber::Normal(n) => n.serialize(s) - } + fn serialize(&self, s: &mut S) -> Result<(), S::Error> { + u32::from(*self).serialize(s) } } impl Deserialize for ChildNumber { - fn deserialize(d: &mut D) -> Result - where D: Deserializer { - let n: u32 = try!(Deserialize::deserialize(d)); - if n < (1 << 31) { - Ok(ChildNumber::Normal(n)) - } else { - Ok(ChildNumber::Hardened(n - (1 << 31))) - } + fn deserialize(d: &mut D) -> Result { + let n: u32 = Deserialize::deserialize(d)?; + + Ok(ChildNumber::from(n)) } } @@ -205,7 +241,7 @@ impl ExtendedPrivKey { network: network, depth: 0, parent_fingerprint: Default::default(), - child_number: ChildNumber::Normal(0), + child_number: ChildNumber::from_normal_idx(0), secret_key: try!(SecretKey::from_slice(secp, &result[..32]).map_err(Error::Ecdsa)), chain_code: ChainCode::from(&result[32..]) }) @@ -227,20 +263,18 @@ impl ExtendedPrivKey { let mut hmac = Hmac::new(Sha512::new(), &self.chain_code[..]); let mut be_n = [0; 4]; match i { - ChildNumber::Normal(n) => { - if n >= (1 << 31) { return Err(Error::InvalidChildNumber(i)) } + ChildNumber::Normal {..} => { // Non-hardened key: compute public data and use that hmac.input(&PublicKey::from_secret_key(secp, &self.secret_key).unwrap().serialize()[..]); - BigEndian::write_u32(&mut be_n, n); } - ChildNumber::Hardened(n) => { - if n >= (1 << 31) { return Err(Error::InvalidChildNumber(i)) } + ChildNumber::Hardened {..} => { // Hardened key: use only secret data to prevent public derivation hmac.input(&[0u8]); hmac.input(&self.secret_key[..]); - BigEndian::write_u32(&mut be_n, n + (1 << 31)); } } + BigEndian::write_u32(&mut be_n, u32::from(i)); + hmac.input(&be_n); hmac.raw_result(&mut result); let mut sk = try!(SecretKey::from_slice(secp, &result[..32]).map_err(Error::Ecdsa)); @@ -296,14 +330,10 @@ impl ExtendedPubKey { /// Compute the scalar tweak added to this key to get a child key pub fn ckd_pub_tweak(&self, secp: &Secp256k1, i: ChildNumber) -> Result<(SecretKey, ChainCode), Error> { match i { - ChildNumber::Hardened(n) => { - if n >= (1 << 31) { - Err(Error::InvalidChildNumber(i)) - } else { - Err(Error::CannotDeriveFromHardenedKey) - } + ChildNumber::Hardened {..} => { + Err(Error::CannotDeriveFromHardenedKey) } - ChildNumber::Normal(n) => { + ChildNumber::Normal { index: n } => { let mut hmac = Hmac::new(Sha512::new(), &self.chain_code[..]); hmac.input(&self.public_key.serialize()[..]); let mut be_n = [0; 4]; @@ -367,14 +397,9 @@ impl ToString for ExtendedPrivKey { }[..]); ret[4] = self.depth as u8; ret[5..9].copy_from_slice(&self.parent_fingerprint[..]); - match self.child_number { - ChildNumber::Hardened(n) => { - BigEndian::write_u32(&mut ret[9..13], n + (1 << 31)); - } - ChildNumber::Normal(n) => { - BigEndian::write_u32(&mut ret[9..13], n); - } - } + + BigEndian::write_u32(&mut ret[9..13], u32::from(self.child_number)); + ret[13..45].copy_from_slice(&self.chain_code[..]); ret[45] = 0; ret[46..78].copy_from_slice(&self.secret_key[..]); @@ -393,9 +418,8 @@ impl FromStr for ExtendedPrivKey { return Err(base58::Error::InvalidLength(data.len())); } - let cn_int = Cursor::new(&data[9..13]).read_u32::().unwrap(); - let child_number = if cn_int < (1 << 31) { ChildNumber::Normal(cn_int) } - else { ChildNumber::Hardened(cn_int - (1 << 31)) }; + let cn_int: u32 = Cursor::new(&data[9..13]).read_u32::().unwrap(); + let child_number: ChildNumber = ChildNumber::from(cn_int); Ok(ExtendedPrivKey { network: if &data[0..4] == [0x04u8, 0x88, 0xAD, 0xE4] { @@ -425,14 +449,9 @@ impl ToString for ExtendedPubKey { }[..]); ret[4] = self.depth as u8; ret[5..9].copy_from_slice(&self.parent_fingerprint[..]); - match self.child_number { - ChildNumber::Hardened(n) => { - BigEndian::write_u32(&mut ret[9..13], n + (1 << 31)); - } - ChildNumber::Normal(n) => { - BigEndian::write_u32(&mut ret[9..13], n); - } - } + + BigEndian::write_u32(&mut ret[9..13], u32::from(self.child_number)); + ret[13..45].copy_from_slice(&self.chain_code[..]); ret[45..78].copy_from_slice(&self.public_key.serialize()[..]); base58::check_encode_slice(&ret[..]) @@ -450,9 +469,8 @@ impl FromStr for ExtendedPubKey { return Err(base58::Error::InvalidLength(data.len())); } - let cn_int = Cursor::new(&data[9..13]).read_u32::().unwrap(); - let child_number = if cn_int < (1 << 31) { ChildNumber::Normal(cn_int) } - else { ChildNumber::Hardened(cn_int - (1 << 31)) }; + let cn_int: u32 = Cursor::new(&data[9..13]).read_u32::().unwrap(); + let child_number: ChildNumber = ChildNumber::from(cn_int); Ok(ExtendedPubKey { network: if &data[0..4] == [0x04u8, 0x88, 0xB2, 0x1E] { @@ -499,12 +517,12 @@ mod tests { for &num in path.iter() { sk = sk.ckd_priv(secp, num).unwrap(); match num { - Normal(_) => { + Normal {..} => { let pk2 = pk.ckd_pub(secp, num).unwrap(); pk = ExtendedPubKey::from_private(secp, &sk); assert_eq!(pk, pk2); } - Hardened(_) => { + Hardened {..} => { pk = ExtendedPubKey::from_private(secp, &sk); } } @@ -530,27 +548,27 @@ mod tests { "xpub661MyMwAqRbcFtXgS5sYJABqqG9YLmC4Q1Rdap9gSE8NqtwybGhePY2gZ29ESFjqJoCu1Rupje8YtGqsefD265TMg7usUDFdp6W1EGMcet8"); // m/0h - test_path(&secp, Bitcoin, &seed, &[Hardened(0)], + test_path(&secp, Bitcoin, &seed, &[ChildNumber::from_hardened_idx(0)], "xprv9uHRZZhk6KAJC1avXpDAp4MDc3sQKNxDiPvvkX8Br5ngLNv1TxvUxt4cV1rGL5hj6KCesnDYUhd7oWgT11eZG7XnxHrnYeSvkzY7d2bhkJ7", "xpub68Gmy5EdvgibQVfPdqkBBCHxA5htiqg55crXYuXoQRKfDBFA1WEjWgP6LHhwBZeNK1VTsfTFUHCdrfp1bgwQ9xv5ski8PX9rL2dZXvgGDnw"); // m/0h/1 - test_path(&secp, Bitcoin, &seed, &[Hardened(0), Normal(1)], + test_path(&secp, Bitcoin, &seed, &[ChildNumber::from_hardened_idx(0), ChildNumber::from_normal_idx(1)], "xprv9wTYmMFdV23N2TdNG573QoEsfRrWKQgWeibmLntzniatZvR9BmLnvSxqu53Kw1UmYPxLgboyZQaXwTCg8MSY3H2EU4pWcQDnRnrVA1xe8fs", "xpub6ASuArnXKPbfEwhqN6e3mwBcDTgzisQN1wXN9BJcM47sSikHjJf3UFHKkNAWbWMiGj7Wf5uMash7SyYq527Hqck2AxYysAA7xmALppuCkwQ"); // m/0h/1/2h - test_path(&secp, Bitcoin, &seed, &[Hardened(0), Normal(1), Hardened(2)], + test_path(&secp, Bitcoin, &seed, &[ChildNumber::from_hardened_idx(0), ChildNumber::from_normal_idx(1), ChildNumber::from_hardened_idx(2)], "xprv9z4pot5VBttmtdRTWfWQmoH1taj2axGVzFqSb8C9xaxKymcFzXBDptWmT7FwuEzG3ryjH4ktypQSAewRiNMjANTtpgP4mLTj34bhnZX7UiM", "xpub6D4BDPcP2GT577Vvch3R8wDkScZWzQzMMUm3PWbmWvVJrZwQY4VUNgqFJPMM3No2dFDFGTsxxpG5uJh7n7epu4trkrX7x7DogT5Uv6fcLW5"); // m/0h/1/2h/2 - test_path(&secp, Bitcoin, &seed, &[Hardened(0), Normal(1), Hardened(2), Normal(2)], + test_path(&secp, Bitcoin, &seed, &[ChildNumber::from_hardened_idx(0), ChildNumber::from_normal_idx(1), ChildNumber::from_hardened_idx(2), ChildNumber::from_normal_idx(2)], "xprvA2JDeKCSNNZky6uBCviVfJSKyQ1mDYahRjijr5idH2WwLsEd4Hsb2Tyh8RfQMuPh7f7RtyzTtdrbdqqsunu5Mm3wDvUAKRHSC34sJ7in334", "xpub6FHa3pjLCk84BayeJxFW2SP4XRrFd1JYnxeLeU8EqN3vDfZmbqBqaGJAyiLjTAwm6ZLRQUMv1ZACTj37sR62cfN7fe5JnJ7dh8zL4fiyLHV"); // m/0h/1/2h/2/1000000000 - test_path(&secp, Bitcoin, &seed, &[Hardened(0), Normal(1), Hardened(2), Normal(2), Normal(1000000000)], + test_path(&secp, Bitcoin, &seed, &[ChildNumber::from_hardened_idx(0), ChildNumber::from_normal_idx(1), ChildNumber::from_hardened_idx(2), ChildNumber::from_normal_idx(2), ChildNumber::from_normal_idx(1000000000)], "xprvA41z7zogVVwxVSgdKUHDy1SKmdb533PjDz7J6N6mV6uS3ze1ai8FHa8kmHScGpWmj4WggLyQjgPie1rFSruoUihUZREPSL39UNdE3BBDu76", "xpub6H1LXWLaKsWFhvm6RVpEL9P4KfRZSW7abD2ttkWP3SSQvnyA8FSVqNTEcYFgJS2UaFcxupHiYkro49S8yGasTvXEYBVPamhGW6cFJodrTHy"); } @@ -566,39 +584,39 @@ mod tests { "xpub661MyMwAqRbcFW31YEwpkMuc5THy2PSt5bDMsktWQcFF8syAmRUapSCGu8ED9W6oDMSgv6Zz8idoc4a6mr8BDzTJY47LJhkJ8UB7WEGuduB"); // m/0 - test_path(&secp, Bitcoin, &seed, &[Normal(0)], + test_path(&secp, Bitcoin, &seed, &[ChildNumber::from_normal_idx(0)], "xprv9vHkqa6EV4sPZHYqZznhT2NPtPCjKuDKGY38FBWLvgaDx45zo9WQRUT3dKYnjwih2yJD9mkrocEZXo1ex8G81dwSM1fwqWpWkeS3v86pgKt", "xpub69H7F5d8KSRgmmdJg2KhpAK8SR3DjMwAdkxj3ZuxV27CprR9LgpeyGmXUbC6wb7ERfvrnKZjXoUmmDznezpbZb7ap6r1D3tgFxHmwMkQTPH"); // m/0/2147483647h - test_path(&secp, Bitcoin, &seed, &[Normal(0), Hardened(2147483647)], + test_path(&secp, Bitcoin, &seed, &[ChildNumber::from_normal_idx(0), ChildNumber::from_hardened_idx(2147483647)], "xprv9wSp6B7kry3Vj9m1zSnLvN3xH8RdsPP1Mh7fAaR7aRLcQMKTR2vidYEeEg2mUCTAwCd6vnxVrcjfy2kRgVsFawNzmjuHc2YmYRmagcEPdU9", "xpub6ASAVgeehLbnwdqV6UKMHVzgqAG8Gr6riv3Fxxpj8ksbH9ebxaEyBLZ85ySDhKiLDBrQSARLq1uNRts8RuJiHjaDMBU4Zn9h8LZNnBC5y4a"); // m/0/2147483647h/1 - test_path(&secp, Bitcoin, &seed, &[Normal(0), Hardened(2147483647), Normal(1)], + test_path(&secp, Bitcoin, &seed, &[ChildNumber::from_normal_idx(0), ChildNumber::from_hardened_idx(2147483647), ChildNumber::from_normal_idx(1)], "xprv9zFnWC6h2cLgpmSA46vutJzBcfJ8yaJGg8cX1e5StJh45BBciYTRXSd25UEPVuesF9yog62tGAQtHjXajPPdbRCHuWS6T8XA2ECKADdw4Ef", "xpub6DF8uhdarytz3FWdA8TvFSvvAh8dP3283MY7p2V4SeE2wyWmG5mg5EwVvmdMVCQcoNJxGoWaU9DCWh89LojfZ537wTfunKau47EL2dhHKon"); // m/0/2147483647h/1/2147483646h - test_path(&secp, Bitcoin, &seed, &[Normal(0), Hardened(2147483647), Normal(1), Hardened(2147483646)], + test_path(&secp, Bitcoin, &seed, &[ChildNumber::from_normal_idx(0), ChildNumber::from_hardened_idx(2147483647), ChildNumber::from_normal_idx(1), ChildNumber::from_hardened_idx(2147483646)], "xprvA1RpRA33e1JQ7ifknakTFpgNXPmW2YvmhqLQYMmrj4xJXXWYpDPS3xz7iAxn8L39njGVyuoseXzU6rcxFLJ8HFsTjSyQbLYnMpCqE2VbFWc", "xpub6ERApfZwUNrhLCkDtcHTcxd75RbzS1ed54G1LkBUHQVHQKqhMkhgbmJbZRkrgZw4koxb5JaHWkY4ALHY2grBGRjaDMzQLcgJvLJuZZvRcEL"); // m/0/2147483647h/1/2147483646h/2 - test_path(&secp, Bitcoin, &seed, &[Normal(0), Hardened(2147483647), Normal(1), Hardened(2147483646), Normal(2)], + test_path(&secp, Bitcoin, &seed, &[ChildNumber::from_normal_idx(0), ChildNumber::from_hardened_idx(2147483647), ChildNumber::from_normal_idx(1), ChildNumber::from_hardened_idx(2147483646), ChildNumber::from_normal_idx(2)], "xprvA2nrNbFZABcdryreWet9Ea4LvTJcGsqrMzxHx98MMrotbir7yrKCEXw7nadnHM8Dq38EGfSh6dqA9QWTyefMLEcBYJUuekgW4BYPJcr9E7j", "xpub6FnCn6nSzZAw5Tw7cgR9bi15UV96gLZhjDstkXXxvCLsUXBGXPdSnLFbdpq8p9HmGsApME5hQTZ3emM2rnY5agb9rXpVGyy3bdW6EEgAtqt"); } #[test] pub fn encode_decode_childnumber() { - serde_round_trip!(Normal(0)); - serde_round_trip!(Normal(1)); - serde_round_trip!(Normal((1 << 31) - 1)); - serde_round_trip!(Hardened(0)); - serde_round_trip!(Hardened(1)); - serde_round_trip!(Hardened((1 << 31) - 1)); + serde_round_trip!(ChildNumber::from_normal_idx(0)); + serde_round_trip!(ChildNumber::from_normal_idx(1)); + serde_round_trip!(ChildNumber::from_normal_idx((1 << 31) - 1)); + serde_round_trip!(ChildNumber::from_hardened_idx(0)); + serde_round_trip!(ChildNumber::from_hardened_idx(1)); + serde_round_trip!(ChildNumber::from_hardened_idx((1 << 31) - 1)); } }