feat(wallet): implement HD private keys & encrypted wrapper (#358)

pallas-txbuilder/Cargo.toml

@@ -18,6 +18,7 @@ pallas-crypto = { path = "../pallas-crypto", version = "=0.20.0" }
 pallas-primitives = { path = "../pallas-primitives", version = "=0.20.0" }
 pallas-traverse = { path = "../pallas-traverse", version = "=0.20.0" }
 pallas-addresses = { path = "../pallas-addresses", version = "=0.20.0" }
+pallas-wallet = { path = "../pallas-wallet", version = "=0.20.0" }
 serde = { version = "1.0.188", features = ["derive"] }
 serde_json = "1.0.107"
 thiserror = "1.0.44"

pallas-txbuilder/src/transaction/model.rs

@@ -4,6 +4,7 @@ use pallas_crypto::{
     key::ed25519,
 };
 use pallas_primitives::{babbage, Fragment};
+use pallas_wallet::PrivateKey;
 
 use std::{collections::HashMap, ops::Deref};
 
@@ -608,14 +609,14 @@ pub struct BuiltTransaction {
 }
 
 impl BuiltTransaction {
-    pub fn sign(mut self, secret_key: ed25519::SecretKey) -> Result<Self, TxBuilderError> {
-        let pubkey: [u8; 32] = secret_key
+    pub fn sign(mut self, private_key: PrivateKey) -> Result<Self, TxBuilderError> {
+        let pubkey: [u8; 32] = private_key
             .public_key()
             .as_ref()
             .try_into()
             .map_err(|_| TxBuilderError::MalformedKey)?;
 
-        let signature: [u8; 64] = secret_key.sign(self.tx_hash.0).as_ref().try_into().unwrap();
+        let signature: [u8; ed25519::Signature::SIZE] = private_key.sign(self.tx_hash.0).as_ref().try_into().unwrap();
 
         match self.era {
             BuilderEra::Babbage => {

pallas-wallet/Cargo.toml

@@ -16,3 +16,4 @@ ed25519-bip32 = "0.4.1"
 bip39 = { version = "2.0.0", features = ["rand_core"] }
 cryptoxide = "0.4.4"
 bech32 = "0.9.1"
+rand = "0.8.5"

pallas-wallet/src/hd.rs

@@ -0,0 +1,192 @@
+use bech32::{FromBase32, ToBase32};
+use bip39::rand_core::{CryptoRng, RngCore};
+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;
+
+use crate::{Error, PrivateKey};
+
+/// 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_private_key(&self) -> PrivateKey {
+        PrivateKey::Extended(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 {
+            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 {
+            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 bip39::rand_core::OsRng;
+
+    use super::{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)
+    }
+}

pallas-wallet/src/lib.rs

@@ -1,13 +1,18 @@
-use bech32::{FromBase32, ToBase32};
-use bip39::rand_core::{CryptoRng, RngCore};
-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 ed25519_bip32;
+use pallas_crypto::key::ed25519::{PublicKey, SecretKey, SecretKeyExtended, Signature};
 use thiserror::Error;
 
+pub mod hd;
+pub mod wrapper;
+
 #[derive(Error, Debug)]
 pub enum Error {
+    /// Private key wrapper data of unexpected length
+    #[error("Wrapped private key data invalid length")]
+    WrapperDataInvalidSize,
+    /// Failed to decrypt private key wrapper data
+    #[error("Failed to decrypt private key wrapper data")]
+    WrapperDataFailedToDecrypt,
     /// Unexpected bech32 HRP prefix
     #[error("Unexpected bech32 HRP prefix")]
     InvalidBech32Hrp,
@@ -28,186 +33,59 @@ pub enum Error {
     DerivationError(ed25519_bip32::DerivationError),
 }
 
-/// ED25519-BIP32 HD Private Key
-#[derive(Debug, PartialEq, Eq)]
-pub struct Bip32PrivateKey(ed25519_bip32::XPrv);
+/// A standard or extended Ed25519 secret key
+pub enum PrivateKey {
+    Normal(SecretKey),
+    Extended(SecretKeyExtended),
+}
 
-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)
+impl PrivateKey {
+    pub fn len(&self) -> usize {
+        match self {
+            Self::Normal(_) => SecretKey::SIZE,
+            Self::Extended(_) => SecretKeyExtended::SIZE,
+        }
     }
 
-    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 public_key(&self) -> PublicKey {
+        match self {
+            Self::Normal(x) => x.public_key(),
+            Self::Extended(x) => x.public_key(),
+        }
     }
 
-    pub fn from_bytes(bytes: [u8; 96]) -> Result<Self, Error> {
-        XPrv::from_bytes_verified(bytes)
-            .map(Self)
-            .map_err(Error::Xprv)
+    pub fn sign<T>(&self, msg: T) -> Signature
+    where
+        T: AsRef<[u8]>,
+    {
+        match self {
+            Self::Normal(x) => x.sign(msg),
+            Self::Extended(x) => x.sign(msg),
+        }
     }
 
     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 {
-            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)?)
+        match self {
+            Self::Normal(x) => {
+                let bytes: [u8; SecretKey::SIZE] = x.clone().into();
+                bytes.to_vec()
+            }
+            Self::Extended(x) => {
+                let bytes: [u8; SecretKeyExtended::SIZE] = x.clone().into();
+                bytes.to_vec()
+            }
         }
     }
 }
 
-/// 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 {
-            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)?,
-            ))
-        }
+impl From<SecretKey> for PrivateKey {
+    fn from(key: SecretKey) -> Self {
+        PrivateKey::Normal(key)
     }
 }
 
-#[cfg(test)]
-mod test {
-    use bip39::rand_core::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)
+impl From<SecretKeyExtended> for PrivateKey {
+    fn from(key: SecretKeyExtended) -> Self {
+        PrivateKey::Extended(key)
     }
 }

pallas-wallet/src/wrapper.rs

@@ -0,0 +1,165 @@
+use cryptoxide::chacha20poly1305::ChaCha20Poly1305;
+use cryptoxide::kdf::argon2;
+use pallas_crypto::key::ed25519::{SecretKey, SecretKeyExtended};
+use rand::{CryptoRng, RngCore};
+
+use crate::{Error, PrivateKey};
+
+const ITERATIONS: u32 = 2500;
+const VERSION_SIZE: usize = 1;
+const SALT_SIZE: usize = 16;
+const NONCE_SIZE: usize = 12;
+const TAG_SIZE: usize = 16;
+
+pub fn encrypt_private_key<Rng>(mut rng: Rng, private_key: PrivateKey, password: &String) -> Vec<u8>
+where
+    Rng: RngCore + CryptoRng,
+{
+    let salt = {
+        let mut salt = [0u8; SALT_SIZE];
+        rng.fill_bytes(&mut salt);
+        salt
+    };
+
+    let sym_key: [u8; 32] = argon2::argon2(
+        &argon2::Params::argon2d().iterations(ITERATIONS).unwrap(),
+        password.as_bytes(),
+        &salt,
+        &[],
+        &[],
+    );
+
+    let nonce = {
+        let mut nonce = [0u8; NONCE_SIZE];
+        rng.fill_bytes(&mut nonce);
+        nonce
+    };
+
+    let mut chacha20 = ChaCha20Poly1305::new(&sym_key, &nonce, &[]);
+
+    let data_size = private_key.len();
+
+    let (ciphertext, ct_tag) = {
+        let mut ciphertext = vec![0u8; data_size];
+        let mut ct_tag = [0u8; 16];
+        chacha20.encrypt(&private_key.as_bytes(), &mut ciphertext, &mut ct_tag);
+
+        (ciphertext, ct_tag)
+    };
+
+    // (version || salt || nonce || tag || ciphertext)
+    let mut out = Vec::with_capacity(VERSION_SIZE + SALT_SIZE + NONCE_SIZE + TAG_SIZE + data_size);
+
+    out.push(1);
+    out.extend_from_slice(&salt);
+    out.extend_from_slice(&nonce);
+    out.extend_from_slice(&ct_tag);
+    out.extend_from_slice(&ciphertext);
+
+    out
+}
+
+#[allow(unused)]
+pub fn decrypt_private_key(password: &String, data: Vec<u8>) -> Result<PrivateKey, Error> {
+    let data_len_without_ct = VERSION_SIZE + SALT_SIZE + NONCE_SIZE + TAG_SIZE;
+
+    let ciphertext_len = if data.len() == (data_len_without_ct + SecretKey::SIZE) {
+        SecretKey::SIZE
+    } else if data.len() == (data_len_without_ct + SecretKeyExtended::SIZE) {
+        SecretKeyExtended::SIZE
+    } else {
+        return Err(Error::WrapperDataInvalidSize);
+    };
+
+    let mut cursor = 0;
+
+    let _version = &data[cursor];
+    cursor += VERSION_SIZE;
+
+    let salt = &data[cursor..cursor + SALT_SIZE];
+    cursor += SALT_SIZE;
+
+    let nonce = &data[cursor..cursor + NONCE_SIZE];
+    cursor += NONCE_SIZE;
+
+    let tag = &data[cursor..cursor + TAG_SIZE];
+    cursor += TAG_SIZE;
+
+    let ciphertext = &data[cursor..cursor + ciphertext_len];
+
+    let sym_key: [u8; 32] = argon2::argon2(
+        &argon2::Params::argon2d().iterations(ITERATIONS).unwrap(),
+        password.as_bytes(),
+        salt,
+        &[],
+        &[],
+    );
+
+    let mut chacha20 = ChaCha20Poly1305::new(&sym_key, nonce, &[]);
+
+    match ciphertext_len {
+        SecretKey::SIZE => {
+            let mut plaintext = [0u8; SecretKey::SIZE];
+
+            if chacha20.decrypt(ciphertext, &mut plaintext, tag) {
+                let secret_key: SecretKey = plaintext.into();
+
+                Ok(secret_key.into())
+            } else {
+                Err(Error::WrapperDataFailedToDecrypt)
+            }
+        }
+        SecretKeyExtended::SIZE => {
+            let mut plaintext = [0u8; SecretKeyExtended::SIZE];
+
+            if chacha20.decrypt(ciphertext, &mut plaintext, tag) {
+                let secret_key: SecretKeyExtended = plaintext.into();
+
+                Ok(secret_key.into())
+            } else {
+                Err(Error::WrapperDataFailedToDecrypt)
+            }
+        }
+        _ => unreachable!(),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use pallas_crypto::key::ed25519::{SecretKey, SecretKeyExtended};
+    use rand::rngs::OsRng;
+
+    use crate::{
+        wrapper::{decrypt_private_key, encrypt_private_key},
+        PrivateKey,
+    };
+
+    #[test]
+    fn private_key_encryption_roundtrip() {
+        let password = "hunter123";
+
+        // --- standard
+
+        let private_key = PrivateKey::Normal(SecretKey::new(OsRng));
+
+        let private_key_bytes = private_key.as_bytes();
+
+        let encrypted_priv_key = encrypt_private_key(OsRng, private_key, &password.into());
+
+        let decrypted_privkey = decrypt_private_key(&password.into(), encrypted_priv_key).unwrap();
+
+        assert_eq!(private_key_bytes, decrypted_privkey.as_bytes());
+
+        // --- extended
+
+        let private_key = PrivateKey::Extended(SecretKeyExtended::new(OsRng));
+
+        let private_key_bytes = private_key.as_bytes();
+
+        let encrypted_priv_key = encrypt_private_key(OsRng, private_key, &password.into());
+
+        let decrypted_privkey = decrypt_private_key(&password.into(), encrypted_priv_key).unwrap();
+
+        assert_eq!(private_key_bytes, decrypted_privkey.as_bytes())
+    }
+}