//! spendable on-chain outputs which the user owns and is responsible for using just as any other
//! on-chain output which is theirs.
-use bitcoin::blockdata::transaction::{OutPoint, TxOut};
+use bitcoin::blockdata::transaction::{Transaction, OutPoint, TxOut};
use bitcoin::blockdata::script::{Script, Builder};
use bitcoin::blockdata::opcodes;
use bitcoin::network::constants::Network;
use bitcoin::util::bip32::{ExtendedPrivKey, ExtendedPubKey, ChildNumber};
+use bitcoin::util::bip143;
use bitcoin_hashes::{Hash, HashEngine};
use bitcoin_hashes::sha256::HashEngine as Sha256State;
use bitcoin_hashes::hash160::Hash as Hash160;
use secp256k1::key::{SecretKey, PublicKey};
-use secp256k1::Secp256k1;
+use secp256k1::{Secp256k1, Signature};
use secp256k1;
use util::byte_utils;
use util::logger::Logger;
+use ln::chan_utils;
+use ln::chan_utils::{TxCreationKeys, HTLCOutputInCommitment};
+
use std::sync::Arc;
use std::sync::atomic::{AtomicUsize, Ordering};
/// A trait to describe an object which can get user secrets and key material.
pub trait KeysInterface: Send + Sync {
+ /// A type which implements ChannelKeys which will be returned by get_channel_keys.
+ type ChanKeySigner : ChannelKeys;
+
/// Get node secret key (aka node_id or network_key)
fn get_node_secret(&self) -> SecretKey;
/// Get destination redeemScript to encumber static protocol exit points.
fn get_shutdown_pubkey(&self) -> PublicKey;
/// Get a new set of ChannelKeys for per-channel secrets. These MUST be unique even if you
/// restarted with some stale data!
- fn get_channel_keys(&self, inbound: bool) -> ChannelKeys;
- /// Get a secret for construting an onion packet
- fn get_session_key(&self) -> SecretKey;
+ fn get_channel_keys(&self, inbound: bool) -> Self::ChanKeySigner;
+ /// Get a secret and PRNG seed for construting an onion packet
+ fn get_onion_rand(&self) -> (SecretKey, [u8; 32]);
/// Get a unique temporary channel id. Channels will be referred to by this until the funding
/// transaction is created, at which point they will use the outpoint in the funding
/// transaction.
fn get_channel_id(&self) -> [u8; 32];
}
-/// Set of lightning keys needed to operate a channel as described in BOLT 3
+/// Set of lightning keys needed to operate a channel as described in BOLT 3.
+///
+/// Signing services could be implemented on a hardware wallet. In this case,
+/// the current ChannelKeys would be a front-end on top of a communication
+/// channel connected to your secure device and lightning key material wouldn't
+/// reside on a hot server. Nevertheless, a this deployment would still need
+/// to trust the ChannelManager to avoid loss of funds as this latest component
+/// could ask to sign commitment transaction with HTLCs paying to attacker pubkeys.
+///
+/// A more secure iteration would be to use hashlock (or payment points) to pair
+/// invoice/incoming HTLCs with outgoing HTLCs to implement a no-trust-ChannelManager
+/// at the price of more state and computation on the hardware wallet side. In the future,
+/// we are looking forward to design such interface.
+///
+/// In any case, ChannelMonitor or fallback watchtowers are always going to be trusted
+/// to act, as liveness and breach reply correctness are always going to be hard requirements
+/// of LN security model, orthogonal of key management issues.
+///
+/// If you're implementing a custom signer, you almost certainly want to implement
+/// Readable/Writable to serialize out a unique reference to this set of keys so
+/// that you can serialize the full ChannelManager object.
+///
+/// (TODO: We shouldn't require that, and should have an API to get them at deser time, due mostly
+/// to the possibility of reentrancy issues by calling the user's code during our deserialization
+/// routine).
+pub trait ChannelKeys : Send {
+ /// Gets the private key for the anchor tx
+ fn funding_key<'a>(&'a self) -> &'a SecretKey;
+ /// Gets the local secret key for blinded revocation pubkey
+ fn revocation_base_key<'a>(&'a self) -> &'a SecretKey;
+ /// Gets the local secret key used in to_remote output of remote commitment tx
+ /// (and also as part of obscured commitment number)
+ fn payment_base_key<'a>(&'a self) -> &'a SecretKey;
+ /// Gets the local secret key used in HTLC-Success/HTLC-Timeout txn and to_local output
+ fn delayed_payment_base_key<'a>(&'a self) -> &'a SecretKey;
+ /// Gets the local htlc secret key used in commitment tx htlc outputs
+ fn htlc_base_key<'a>(&'a self) -> &'a SecretKey;
+ /// Gets the commitment seed
+ fn commitment_seed<'a>(&'a self) -> &'a [u8; 32];
+
+ /// Create a signature for a remote commitment transaction and associated HTLC transactions.
+ ///
+ /// Note that if signing fails or is rejected, the channel will be force-closed.
+ ///
+ /// TODO: Document the things someone using this interface should enforce before signing.
+ /// TODO: Add more input vars to enable better checking (preferably removing commitment_tx and
+ /// making the callee generate it via some util function we expose)!
+ fn sign_remote_commitment<T: secp256k1::Signing>(&self, channel_value_satoshis: u64, channel_funding_script: &Script, feerate_per_kw: u64, commitment_tx: &Transaction, keys: &TxCreationKeys, htlcs: &[&HTLCOutputInCommitment], to_self_delay: u16, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()>;
+}
+
#[derive(Clone)]
-pub struct ChannelKeys {
+/// A simple implementation of ChannelKeys that just keeps the private keys in memory.
+pub struct InMemoryChannelKeys {
/// Private key of anchor tx
pub funding_key: SecretKey,
/// Local secret key for blinded revocation pubkey
pub commitment_seed: [u8; 32],
}
-impl_writeable!(ChannelKeys, 0, {
+impl ChannelKeys for InMemoryChannelKeys {
+ fn funding_key(&self) -> &SecretKey { &self.funding_key }
+ fn revocation_base_key(&self) -> &SecretKey { &self.revocation_base_key }
+ fn payment_base_key(&self) -> &SecretKey { &self.payment_base_key }
+ fn delayed_payment_base_key(&self) -> &SecretKey { &self.delayed_payment_base_key }
+ fn htlc_base_key(&self) -> &SecretKey { &self.htlc_base_key }
+ fn commitment_seed(&self) -> &[u8; 32] { &self.commitment_seed }
+
+
+ fn sign_remote_commitment<T: secp256k1::Signing>(&self, channel_value_satoshis: u64, channel_funding_script: &Script, feerate_per_kw: u64, commitment_tx: &Transaction, keys: &TxCreationKeys, htlcs: &[&HTLCOutputInCommitment], to_self_delay: u16, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()> {
+ if commitment_tx.input.len() != 1 { return Err(()); }
+ let commitment_sighash = hash_to_message!(&bip143::SighashComponents::new(&commitment_tx).sighash_all(&commitment_tx.input[0], &channel_funding_script, channel_value_satoshis)[..]);
+ let commitment_sig = secp_ctx.sign(&commitment_sighash, &self.funding_key);
+
+ let commitment_txid = commitment_tx.txid();
+
+ let mut htlc_sigs = Vec::with_capacity(htlcs.len());
+ for ref htlc in htlcs {
+ if let Some(_) = htlc.transaction_output_index {
+ let htlc_tx = chan_utils::build_htlc_transaction(&commitment_txid, feerate_per_kw, to_self_delay, htlc, &keys.a_delayed_payment_key, &keys.revocation_key);
+ let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &keys);
+ let htlc_sighash = hash_to_message!(&bip143::SighashComponents::new(&htlc_tx).sighash_all(&htlc_tx.input[0], &htlc_redeemscript, htlc.amount_msat / 1000)[..]);
+ let our_htlc_key = match chan_utils::derive_private_key(&secp_ctx, &keys.per_commitment_point, &self.htlc_base_key) {
+ Ok(s) => s,
+ Err(_) => return Err(()),
+ };
+ htlc_sigs.push(secp_ctx.sign(&htlc_sighash, &our_htlc_key));
+ }
+ }
+
+ Ok((commitment_sig, htlc_sigs))
+ }
+}
+
+impl_writeable!(InMemoryChannelKeys, 0, {
funding_key,
revocation_base_key,
payment_base_key,
}
impl KeysInterface for KeysManager {
+ type ChanKeySigner = InMemoryChannelKeys;
+
fn get_node_secret(&self) -> SecretKey {
self.node_secret.clone()
}
self.shutdown_pubkey.clone()
}
- fn get_channel_keys(&self, _inbound: bool) -> ChannelKeys {
+ fn get_channel_keys(&self, _inbound: bool) -> InMemoryChannelKeys {
// We only seriously intend to rely on the channel_master_key for true secure
// entropy, everything else just ensures uniqueness. We rely on the unique_start (ie
// starting_time provided in the constructor) to be unique.
let delayed_payment_base_key = key_step!(b"delayed payment base key", payment_base_key);
let htlc_base_key = key_step!(b"HTLC base key", delayed_payment_base_key);
- ChannelKeys {
+ InMemoryChannelKeys {
funding_key,
revocation_base_key,
payment_base_key,
}
}
- fn get_session_key(&self) -> SecretKey {
+ fn get_onion_rand(&self) -> (SecretKey, [u8; 32]) {
let mut sha = self.unique_start.clone();
let child_ix = self.session_child_index.fetch_add(1, Ordering::AcqRel);
let child_privkey = self.session_master_key.ckd_priv(&self.secp_ctx, ChildNumber::from_hardened_idx(child_ix as u32).expect("key space exhausted")).expect("Your RNG is busted");
sha.input(&child_privkey.private_key.key[..]);
- SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("Your RNG is busted")
+
+ let mut rng_seed = sha.clone();
+ // Not exactly the most ideal construction, but the second value will get fed into
+ // ChaCha so it is another step harder to break.
+ rng_seed.input(b"RNG Seed Salt");
+ sha.input(b"Session Key Salt");
+ (SecretKey::from_slice(&Sha256::from_engine(sha).into_inner()).expect("Your RNG is busted"),
+ Sha256::from_engine(rng_seed).into_inner())
}
fn get_channel_id(&self) -> [u8; 32] {
projects / rust-lightning / blobdiff