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Make mnemonic RNG selection explicit #253

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benthecarman wants to merge 1 commit into from
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Make mnemonic RNG selection explicit #253

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7 changes: 5 additions & 2 deletions e2e-tests/tests/e2e.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -17,7 +17,9 @@ use e2e_tests::{
LdkServerHandle, TestBitcoind,
};
use hex_conservative::{DisplayHex, FromHex};
use ldk_node::bip39::{rand::rngs::OsRng, Language, Mnemonic};
use ldk_node::bitcoin::hashes::{sha256, Hash};
use ldk_node::entropy::NodeEntropy;
use ldk_node::lightning::ln::msgs::SocketAddress;
use ldk_node::lightning::offers::offer::Offer;
use ldk_node::lightning_invoice::Bolt11Invoice;
Expand Down Expand Up @@ -1244,8 +1246,9 @@ async fn test_forwarded_payment_event() {
let b_addr = SocketAddress::from_str(&format!("127.0.0.1:{}", server_b.p2p_port)).unwrap();
builder_c.add_liquidity_source(b_node_id, b_addr, None, true);

let mnemonic_c = ldk_node::entropy::generate_entropy_mnemonic(None);
let node_entropy_c = ldk_node::entropy::NodeEntropy::from_bip39_mnemonic(mnemonic_c, None);
let mut rng = OsRng;
let mnemonic_c = Mnemonic::generate_in_with(&mut rng, Language::English, 24).unwrap();
let node_entropy_c = NodeEntropy::from_bip39_mnemonic(mnemonic_c, None);
let node_c = builder_c.build(node_entropy_c).unwrap();

node_c.start().unwrap();
Expand Down
11 changes: 9 additions & 2 deletions ldk-server/src/util/entropy.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -12,12 +12,13 @@ use std::str::FromStr;
use std::{fs, io};

use ldk_node::bip39::Mnemonic;
use ldk_node::entropy::{generate_entropy_mnemonic, NodeEntropy};
use ldk_node::entropy::NodeEntropy;
use log::info;

use crate::util::write_new;

const DEFAULT_MNEMONIC_FILE: &str = "keys_mnemonic";
const DEFAULT_MNEMONIC_ENTROPY_BYTES: usize = 32;

pub(crate) fn load_or_generate_node_entropy(storage_dir: &Path) -> io::Result<NodeEntropy> {
let mnemonic_path = storage_dir.join(DEFAULT_MNEMONIC_FILE);
Expand All @@ -34,7 +35,7 @@ pub(crate) fn load_or_generate_node_entropy(storage_dir: &Path) -> io::Result<No
if let Some(parent) = mnemonic_path.parent() {
fs::create_dir_all(parent)?;
}
let mnemonic = generate_entropy_mnemonic(None);
let mnemonic = generate_entropy_mnemonic()?;
write_new(&mnemonic_path, format!("{}\n", mnemonic).as_bytes(), 0o600)?;
info!(
"Generated new BIP39 mnemonic at {}. Back up this file securely — it is required to recover on-chain funds.",
Expand All @@ -46,6 +47,12 @@ pub(crate) fn load_or_generate_node_entropy(storage_dir: &Path) -> io::Result<No
Ok(NodeEntropy::from_bip39_mnemonic(mnemonic, None))
}

fn generate_entropy_mnemonic() -> io::Result<Mnemonic> {

@tankyleo tankyleo Aug 3, 2026

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I think this deserves a fix in ldk-node and bip39 no ?

@benthecarman benthecarman Aug 3, 2026

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yeah i guess that makes more sense

let mut entropy = [0u8; DEFAULT_MNEMONIC_ENTROPY_BYTES];
getrandom::getrandom(&mut entropy).map_err(io::Error::other)?;
Ok(Mnemonic::from_entropy(&entropy).expect("32-byte entropy must produce a valid mnemonic"))
}

#[cfg(test)]
mod tests {
use std::os::unix::fs::{MetadataExt, PermissionsExt};
Expand Down