feat: introduce wallet crate for ed25519-bip32 key management (#342)

Co-authored-by: Santiago Carmuega <santiago@carmuega.me>

pallas-wallet/src/lib.rs

@@ -0,0 +1,213 @@
+use bech32::{FromBase32, ToBase32};
+use bip39::{Language, Mnemonic};
+use cryptoxide::{hmac::Hmac, pbkdf2::pbkdf2, sha2::Sha512};
+use ed25519_bip32::{self, XPrv, XPub, XPRV_SIZE};
+use pallas_crypto::key::ed25519::{self};
+use rand::{CryptoRng, RngCore};
+use thiserror::Error;
+
+#[derive(Error, Debug)]
+pub enum Error {
+    /// Unexpected bech32 HRP prefix
+    #[error("Unexpected bech32 HRP prefix")]
+    InvalidBech32Hrp,
+    /// Unable to decode bech32 string
+    #[error("Unable to decode bech32: {0}")]
+    InvalidBech32(bech32::Error),
+    /// Decoded bech32 data of unexpected length
+    #[error("Decoded bech32 data of unexpected length")]
+    UnexpectedBech32Length,
+    /// Error relating to ed25519-bip32 private key
+    #[error("Error relating to ed25519-bip32 private key: {0}")]
+    Xprv(ed25519_bip32::PrivateKeyError),
+    /// Error relating to bip39 mnemonic
+    #[error("Error relating to bip39 mnemonic: {0}")]
+    Mnemonic(bip39::Error),
+    /// Error when attempting to derive ed25519-bip32 key
+    #[error("Error when attempting to derive ed25519-bip32 key: {0}")]
+    DerivationError(ed25519_bip32::DerivationError),
+}
+
+/// ED25519-BIP32 HD Private Key
+#[derive(Debug, PartialEq, Eq)]
+pub struct Bip32PrivateKey(ed25519_bip32::XPrv);
+
+impl Bip32PrivateKey {
+    const BECH32_HRP: &'static str = "xprv";
+
+    pub fn generate<T: RngCore + CryptoRng>(mut rng: T) -> Self {
+        let mut buf = [0u8; XPRV_SIZE];
+        rng.fill_bytes(&mut buf);
+        let xprv = XPrv::normalize_bytes_force3rd(buf);
+
+        Self(xprv)
+    }
+
+    pub fn generate_with_mnemonic<T: RngCore + CryptoRng>(
+        mut rng: T,
+        password: String,
+    ) -> (Self, Mnemonic) {
+        let mut buf = [0u8; 64];
+        rng.fill_bytes(&mut buf);
+
+        let bip39 = Mnemonic::generate_in_with(&mut rng, Language::English, 24).unwrap();
+
+        let entropy = bip39.clone().to_entropy();
+
+        let mut pbkdf2_result = [0; XPRV_SIZE];
+
+        const ITER: u32 = 4096; // TODO: BIP39 says 2048, CML uses 4096?
+
+        let mut mac = Hmac::new(Sha512::new(), password.as_bytes());
+        pbkdf2(&mut mac, &entropy, ITER, &mut pbkdf2_result);
+
+        (Self(XPrv::normalize_bytes_force3rd(pbkdf2_result)), bip39)
+    }
+
+    pub fn from_bytes(bytes: [u8; 96]) -> Result<Self, Error> {
+        XPrv::from_bytes_verified(bytes)
+            .map(Self)
+            .map_err(Error::Xprv)
+    }
+
+    pub fn as_bytes(&self) -> Vec<u8> {
+        self.0.as_ref().to_vec()
+    }
+
+    pub fn from_bip39_mnenomic(mnemonic: String, password: String) -> Result<Self, Error> {
+        let bip39 = Mnemonic::parse(mnemonic).map_err(Error::Mnemonic)?;
+        let entropy = bip39.to_entropy();
+
+        let mut pbkdf2_result = [0; XPRV_SIZE];
+
+        const ITER: u32 = 4096; // TODO: BIP39 says 2048, CML uses 4096?
+
+        let mut mac = Hmac::new(Sha512::new(), password.as_bytes());
+        pbkdf2(&mut mac, &entropy, ITER, &mut pbkdf2_result);
+
+        Ok(Self(XPrv::normalize_bytes_force3rd(pbkdf2_result)))
+    }
+
+    pub fn derive(&self, index: u32) -> Self {
+        Self(self.0.derive(ed25519_bip32::DerivationScheme::V2, index))
+    }
+
+    pub fn to_ed25519_privkey(&self) -> ed25519::SecretKeyExtended {
+        self.0.extended_secret_key().into()
+    }
+
+    pub fn to_public(&self) -> Bip32PublicKey {
+        Bip32PublicKey(self.0.public())
+    }
+
+    pub fn chain_code(&self) -> [u8; 32] {
+        *self.0.chain_code()
+    }
+
+    pub fn to_bech32(&self) -> String {
+        bech32::encode(
+            Self::BECH32_HRP,
+            self.as_bytes().to_base32(),
+            bech32::Variant::Bech32,
+        )
+        .unwrap()
+    }
+
+    pub fn from_bech32(bech32: String) -> Result<Self, Error> {
+        let (hrp, data, _) = bech32::decode(&bech32).map_err(Error::InvalidBech32)?;
+        if hrp != Self::BECH32_HRP {
+            return Err(Error::InvalidBech32Hrp);
+        } else {
+            let data = Vec::<u8>::from_base32(&data).map_err(Error::InvalidBech32)?;
+            Self::from_bytes(data.try_into().map_err(|_| Error::UnexpectedBech32Length)?)
+        }
+    }
+}
+
+/// ED25519-BIP32 HD Public Key
+#[derive(Debug, PartialEq, Eq)]
+pub struct Bip32PublicKey(ed25519_bip32::XPub);
+
+impl Bip32PublicKey {
+    const BECH32_HRP: &'static str = "xpub";
+
+    pub fn from_bytes(bytes: [u8; 64]) -> Self {
+        Self(XPub::from_bytes(bytes))
+    }
+
+    pub fn as_bytes(&self) -> Vec<u8> {
+        self.0.as_ref().to_vec()
+    }
+
+    pub fn derive(&self, index: u32) -> Result<Self, Error> {
+        self.0
+            .derive(ed25519_bip32::DerivationScheme::V2, index)
+            .map(Self)
+            .map_err(Error::DerivationError)
+    }
+
+    pub fn to_ed25519_pubkey(&self) -> ed25519::PublicKey {
+        self.0.public_key().into()
+    }
+
+    pub fn chain_code(&self) -> [u8; 32] {
+        *self.0.chain_code()
+    }
+
+    pub fn to_bech32(&self) -> String {
+        bech32::encode(
+            Self::BECH32_HRP,
+            self.as_bytes().to_base32(),
+            bech32::Variant::Bech32,
+        )
+        .unwrap()
+    }
+
+    pub fn from_bech32(bech32: String) -> Result<Self, Error> {
+        let (hrp, data, _) = bech32::decode(&bech32).map_err(Error::InvalidBech32)?;
+        if hrp != Self::BECH32_HRP {
+            return Err(Error::InvalidBech32Hrp);
+        } else {
+            let data = Vec::<u8>::from_base32(&data).map_err(Error::InvalidBech32)?;
+            Ok(Self::from_bytes(
+                data.try_into().map_err(|_| Error::UnexpectedBech32Length)?,
+            ))
+        }
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use rand::rngs::OsRng;
+
+    use crate::{Bip32PrivateKey, Bip32PublicKey};
+
+    #[test]
+    fn mnemonic_roundtrip() {
+        let (xprv, mne) = Bip32PrivateKey::generate_with_mnemonic(OsRng, "".into());
+
+        let xprv_from_mne =
+            Bip32PrivateKey::from_bip39_mnenomic(mne.to_string(), "".into()).unwrap();
+
+        assert_eq!(xprv, xprv_from_mne)
+    }
+
+    #[test]
+    fn bech32_roundtrip() {
+        let xprv = Bip32PrivateKey::generate(OsRng);
+
+        let xprv_bech32 = xprv.to_bech32();
+
+        let decoded_xprv = Bip32PrivateKey::from_bech32(xprv_bech32).unwrap();
+
+        assert_eq!(xprv, decoded_xprv);
+
+        let xpub = xprv.to_public();
+
+        let xpub_bech32 = xpub.to_bech32();
+
+        let decoded_xpub = Bip32PublicKey::from_bech32(xpub_bech32).unwrap();
+
+        assert_eq!(xpub, decoded_xpub)
+    }
+}