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Clean up derive_node_secret_from_mnemonic #29

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Merged
ovitrif merged 1 commit into from
Jan 12, 2026
Merged

Clean up derive_node_secret_from_mnemonic #29

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26 changes: 11 additions & 15 deletions src/io/utils.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,8 @@ use bdk_chain::tx_graph::ChangeSet as BdkTxGraphChangeSet;
use bdk_chain::ConfirmationBlockTime;
use bdk_wallet::ChangeSet as BdkWalletChangeSet;
use bip39::Mnemonic;
use bitcoin::bip32::Xpriv;
use bitcoin::bip32::{ChildNumber, Xpriv};
use bitcoin::secp256k1::Secp256k1;
use bitcoin::Network;
use lightning::io::Cursor;
use lightning::ln::msgs::DecodeError;
Expand Down Expand Up @@ -83,24 +84,19 @@ pub fn generate_entropy_mnemonic(word_count: Option<WordCount>) -> Mnemonic {
pub fn derive_node_secret_from_mnemonic(
mnemonic: String, passphrase: Option<String>,
) -> Result<Vec<u8>, Error> {
use bitcoin::bip32::ChildNumber;
use bitcoin::secp256k1::Secp256k1;

let parsed_mnemonic = Mnemonic::parse(&mnemonic).map_err(|_| Error::InvalidMnemonic)?;
let seed = parsed_mnemonic.to_seed(passphrase.as_deref().unwrap_or(""));

// First BIP32 derivation: 64-byte BIP39 seed → 32-byte master private key
let xpriv =
let master_xpriv =
Xpriv::new_master(Network::Bitcoin, &seed).map_err(|_| Error::InvalidMnemonic)?;
let ldk_seed: [u8; 32] = xpriv.private_key.secret_bytes();

// Second BIP32 derivation: KeysManager treats the 32-byte key as a new seed
// and derives node_secret at path m/0'
let secp = Secp256k1::new();
let keys_master =
Xpriv::new_master(Network::Bitcoin, &ldk_seed).map_err(|_| Error::InvalidMnemonic)?;
let node_secret_xpriv = keys_master
.derive_priv(&secp, &[ChildNumber::from_hardened_idx(0).unwrap()])

let ldk_seed_bytes: [u8; 32] = master_xpriv.private_key.secret_bytes();

let keys_manager_master = Xpriv::new_master(Network::Bitcoin, &ldk_seed_bytes)
.map_err(|_| Error::InvalidMnemonic)?;

let node_secret_xpriv = keys_manager_master
.derive_priv(&Secp256k1::new(), &[ChildNumber::from_hardened_idx(0).unwrap()])
.map_err(|_| Error::InvalidMnemonic)?;

Ok(node_secret_xpriv.private_key.secret_bytes().to_vec())
Expand Down