aldabra/crates/aldabra-core/src/lib.rs

//! aldabra core — keys, addresses, signing.
//!
//! This crate is the security boundary. Everything that touches private
//! key material lives here, and only here. No I/O, no network, no MCP.
//!
//! ## Layout
//!
//! - [`Mnemonic`]                — 24-word BIP-39 input → entropy bytes.
//! - [`Mnemonic::into_root_key`] — Icarus CIP-3 master-key generation.
//! - [`RootKey`]                 — wraps [`ed25519_bip32::XPrv`].
//! - [`Network`]                 — bech32 prefix + protocol magic selector.
//!
//! Phases 1.3 (CIP-1852 child derivation), 1.4 (real base-address
//! construction), and signing land in follow-up modules; the placeholder
//! [`derive_base_address`] returns a sentinel address until then.
//!
//! ## Memory hygiene rule
//!
//! Anything holding private-key material zeroizes on drop:
//! - [`Mnemonic`]'s entropy via `ZeroizeOnDrop`.
//! - [`RootKey`]'s [`XPrv`] via its own [`Drop`] impl in `ed25519-bip32`.
//!
//! The decrypted phrase passed into [`Mnemonic::from_phrase`] is the
//! caller's responsibility to drop promptly — we copy the entropy out
//! and don't hold the source string.

use bip39::{Language, Mnemonic as Bip39Mnemonic};
use cryptoxide::hmac::Hmac;
use cryptoxide::pbkdf2::pbkdf2;
use cryptoxide::sha2::Sha512;
use ed25519_bip32::{XPrv, XPRV_SIZE};
use pallas_addresses::{
    Network as PallasNetwork, ShelleyAddress, ShelleyDelegationPart, ShelleyPaymentPart,
};
use thiserror::Error;
use zeroize::ZeroizeOnDrop;

pub mod cip68;
pub mod derive;
pub mod metadata;
pub mod mint;
pub mod plutus;
pub mod sign;
pub mod stake;
pub mod tx;
pub use cip68::{
    build_cip68_datum_cbor, ft_asset_name, ref_nft_asset_name, user_nft_asset_name,
};
pub use derive::{derive_payment_key, derive_stake_key, PaymentKey, StakeKey};
// Stake address derivation lives directly on StakeKey — exported above.
pub use metadata::{build_cip25_aux_data, CIP25_LABEL};
pub use mint::{
    build_signed_cip68_nft_mint, build_signed_mint, build_signed_mint_with_metadata,
    build_unsigned_mint, PolicySpec,
};
pub use sign::add_witness;
pub use plutus::{
    build_signed_plutus_spend, looks_like_script_address, PlutusExUnits, PlutusInput,
    PlutusVersion, DEFAULT_EX_UNITS, MIN_COLLATERAL_LOVELACE,
};
pub use stake::{build_signed_stake_delegation, parse_pool_id, STAKE_KEY_DEPOSIT_LOVELACE};
pub use tx::{
    build_signed_payment, build_signed_payment_with_assets, build_unsigned_payment,
    build_unsigned_payment_with_assets, hex_decode, AssetSpec, InputUtxo, PaymentSummary,
    ProtocolParams, UnsignedPayment,
};

#[derive(Debug, Error)]
pub enum WalletError {
    #[error("invalid mnemonic: {0}")]
    InvalidMnemonic(String),

    #[error("derivation failed: {0}")]
    Derivation(String),

    #[error("address encoding failed: {0}")]
    Address(String),

    #[error("not yet implemented (phase 1 scaffold)")]
    NotYetImplemented,
}

/// A 24-word BIP-39 mnemonic, parsed and validated. Stores the raw
/// 32-byte entropy rather than the phrase — the source string is the
/// caller's responsibility to drop.
///
/// `ZeroizeOnDrop` ensures the entropy is wiped from RAM when this
/// struct is dropped.
#[derive(ZeroizeOnDrop)]
pub struct Mnemonic {
    /// 256 bits of entropy (24 BIP-39 words × 11 bits = 264 bits, the
    /// trailing 8 are the checksum). The bip39 crate's `to_entropy()`
    /// returns exactly the 32 entropy bytes.
    entropy: [u8; 32],
}

impl Mnemonic {
    /// Parse a 24-word English mnemonic, validating word count + checksum.
    /// Drops the source phrase reference immediately after extracting
    /// entropy.
    pub fn from_phrase(phrase: &str) -> Result<Self, WalletError> {
        let parsed = Bip39Mnemonic::parse_in(Language::English, phrase)
            .map_err(|e| WalletError::InvalidMnemonic(e.to_string()))?;
        if parsed.word_count() != 24 {
            return Err(WalletError::InvalidMnemonic(format!(
                "expected 24 words, got {}",
                parsed.word_count()
            )));
        }
        let entropy_vec = parsed.to_entropy();
        let entropy: [u8; 32] = entropy_vec.try_into().map_err(|v: Vec<u8>| {
            WalletError::InvalidMnemonic(format!(
                "expected 32 entropy bytes for 24-word mnemonic, got {}",
                v.len()
            ))
        })?;
        Ok(Self { entropy })
    }

    /// Derive the Cardano CIP-3 root extended private key (Icarus
    /// variant, no passphrase). Consumes the mnemonic so the entropy
    /// is dropped + zeroized immediately after.
    pub fn into_root_key(self) -> Result<RootKey, WalletError> {
        self.into_root_key_with_passphrase("")
    }

    /// Derive the Cardano CIP-3 root extended private key with a
    /// caller-supplied BIP-39 passphrase. Empty string = no passphrase
    /// = the default Icarus / Yoroi behaviour.
    ///
    /// Algorithm (per Cardano Icarus master-key generation):
    /// 1. `xprv = PBKDF2-HMAC-SHA512(password=passphrase, salt=entropy,
    ///                                c=4096, dkLen=96)`
    /// 2. Bit-clamp the first 32 bytes so the result is a valid extended
    ///    Ed25519 scalar with the 3rd-highest bit cleared
    ///    (`normalize_bytes_force3rd`).
    pub fn into_root_key_with_passphrase(
        self,
        passphrase: &str,
    ) -> Result<RootKey, WalletError> {
        let mut xprv_bytes = [0u8; XPRV_SIZE];
        let mut hmac = Hmac::new(Sha512::new(), passphrase.as_bytes());
        pbkdf2(&mut hmac, &self.entropy, 4096, &mut xprv_bytes);

        let xprv = XPrv::normalize_bytes_force3rd(xprv_bytes);
        Ok(RootKey { xprv })
    }
}

/// CIP-3 root extended private key. Wraps an [`XPrv`]
/// (96 bytes: extended secret + chain code). [`XPrv`]'s own [`Drop`]
/// impl wipes the bytes from memory when this struct drops.
pub struct RootKey {
    pub(crate) xprv: XPrv,
}

impl RootKey {
    /// Borrow the underlying [`XPrv`] for derivation. Crate-internal
    /// code uses this; external callers should go through the
    /// `derive_*` helpers which return purpose-specific key types.
    pub(crate) fn xprv(&self) -> &XPrv {
        &self.xprv
    }
}

/// Network parameter — bech32 prefix + protocol magic.
#[derive(Debug, Clone, Copy, PartialEq, Eq, serde::Serialize, serde::Deserialize)]
pub enum Network {
    Mainnet,
    Preview,
    Preprod,
}

impl Network {
    pub fn bech32_hrp_prefix(&self) -> &'static str {
        match self {
            Network::Mainnet => "addr",
            Network::Preview | Network::Preprod => "addr_test",
        }
    }

    /// Map our three-variant Network onto pallas-addresses' two
    /// real variants. Cardano's network header byte only distinguishes
    /// `Mainnet` from `Testnet` — the protocol magic differentiates
    /// Preview vs Preprod at the chain layer, not at the address layer.
    /// Both testnet flavours therefore share the `addr_test1…` HRP.
    pub fn to_pallas(&self) -> PallasNetwork {
        match self {
            Network::Mainnet => PallasNetwork::Mainnet,
            Network::Preview | Network::Preprod => PallasNetwork::Testnet,
        }
    }
}

/// Derive a Shelley base address (payment + stake) at the given
/// account / payment-index path:
///
/// - payment path: `m/1852'/1815'/account'/0/index`
/// - stake path:   `m/1852'/1815'/account'/2/0`
///
/// Both keys hash through Blake2b-224 to produce 28-byte key hashes,
/// which combine via [`ShelleyPaymentPart::key_hash`] +
/// [`ShelleyDelegationPart::key_hash`] into a Shelley base address,
/// emitted as bech32 with the right HRP for the chosen network.
pub fn derive_base_address(
    root: &RootKey,
    network: Network,
    account: u32,
    index: u32,
) -> Result<String, WalletError> {
    let payment = derive_payment_key(root, account, index);
    let stake = derive_stake_key(root, account);

    let address = ShelleyAddress::new(
        network.to_pallas(),
        ShelleyPaymentPart::key_hash(payment.public_key_hash()),
        ShelleyDelegationPart::key_hash(stake.public_key_hash()),
    );

    address
        .to_bech32()
        .map_err(|e| WalletError::Address(e.to_string()))
}

#[cfg(test)]
mod tests {
    use super::*;

    /// Canonical 24-word BIP-39 test mnemonic. Used widely in the
    /// Cardano ecosystem (cardano-address, cardano-cli docs) so derived
    /// vectors are easy to cross-check.
    const ABANDON_ART: &str = concat!(
        "abandon abandon abandon abandon abandon abandon ",
        "abandon abandon abandon abandon abandon abandon ",
        "abandon abandon abandon abandon abandon abandon ",
        "abandon abandon abandon abandon abandon art",
    );

    /// `Mnemonic` deliberately doesn't `derive(Debug)` — printing the
    /// entropy in a panic message would leak key material. Tests use
    /// this helper instead of `.unwrap_err()` (which requires `Debug`
    /// on the `Ok` variant).
    fn expect_invalid(result: Result<Mnemonic, WalletError>) -> WalletError {
        match result {
            Ok(_) => panic!("expected WalletError::InvalidMnemonic, got Ok(_)"),
            Err(e) => e,
        }
    }

    #[test]
    fn rejects_short_phrase() {
        let err = expect_invalid(Mnemonic::from_phrase("one two three"));
        assert!(matches!(err, WalletError::InvalidMnemonic(_)));
    }

    #[test]
    fn rejects_bad_checksum() {
        // 24 abandons in a row has a bad checksum — the canonical valid
        // form ends in "art".
        let bad = "abandon ".repeat(24);
        let err = expect_invalid(Mnemonic::from_phrase(bad.trim()));
        assert!(matches!(err, WalletError::InvalidMnemonic(_)));
    }

    #[test]
    fn parses_canonical_24_word_mnemonic() {
        let m = Mnemonic::from_phrase(ABANDON_ART).expect("valid mnemonic");
        // 24 abandon-mostly words → entropy is all zeros.
        assert_eq!(m.entropy, [0u8; 32]);
    }

    #[test]
    fn derives_root_key_from_canonical_mnemonic() {
        let m = Mnemonic::from_phrase(ABANDON_ART).unwrap();
        let root = m.into_root_key().expect("CIP-3 derivation works");
        // The derived XPrv must be 96 bytes total and the bit-clamp
        // must have cleared the 3rd highest bit at byte 31.
        assert_eq!(root.xprv().as_ref().len(), XPRV_SIZE);
        assert!(root.xprv().is_3rd_highest_bit_clear());
    }

    #[test]
    fn mainnet_base_address_round_trips() {
        let m = Mnemonic::from_phrase(ABANDON_ART).unwrap();
        let root = m.into_root_key().unwrap();
        let addr = derive_base_address(&root, Network::Mainnet, 0, 0).unwrap();
        assert!(addr.starts_with("addr1"), "got: {addr}");
        // Round-trip — pallas should parse what we just emitted and
        // give back a Shelley mainnet address.
        let parsed = pallas_addresses::Address::from_bech32(&addr)
            .expect("our own bech32 output parses");
        match parsed {
            pallas_addresses::Address::Shelley(s) => {
                assert_eq!(s.network(), pallas_addresses::Network::Mainnet);
            }
            other => panic!("expected Shelley address, got {other:?}"),
        }
    }

    #[test]
    fn preprod_base_address_uses_testnet_hrp() {
        let m = Mnemonic::from_phrase(ABANDON_ART).unwrap();
        let root = m.into_root_key().unwrap();
        let addr = derive_base_address(&root, Network::Preprod, 0, 0).unwrap();
        assert!(addr.starts_with("addr_test1"), "got: {addr}");
    }

    #[test]
    fn different_indices_produce_different_addresses() {
        let m = Mnemonic::from_phrase(ABANDON_ART).unwrap();
        let root = m.into_root_key().unwrap();
        let a0 = derive_base_address(&root, Network::Mainnet, 0, 0).unwrap();
        let a1 = derive_base_address(&root, Network::Mainnet, 0, 1).unwrap();
        assert_ne!(a0, a1);
    }
}