fn ecdh(&self, recipient: Recipient, other_key: &PublicKey, tweak: Option<&Scalar>) -> Result<SharedSecret, ()>;
/// Sign an invoice.
+ ///
/// By parameterizing by the raw invoice bytes instead of the hash, we allow implementors of
/// this trait to parse the invoice and make sure they're signing what they expect, rather than
/// blindly signing the hash.
- /// The hrp is ascii bytes, while the invoice data is base32.
+ ///
+ /// The `hrp_bytes` are ASCII bytes, while the `invoice_data` is base32.
///
/// The secret key used to sign the invoice is dependent on the [`Recipient`].
///
// 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 child_privkey = self.channel_master_key.ckd_priv(&self.secp_ctx, ChildNumber::from_hardened_idx(chan_id as u32).expect("key space exhausted")).expect("Your RNG is busted");
+ let child_privkey = self.channel_master_key.ckd_priv(&self.secp_ctx,
+ ChildNumber::from_hardened_idx((chan_id as u32) % (1 << 31)).expect("key space exhausted")
+ ).expect("Your RNG is busted");
unique_start.input(&child_privkey.private_key[..]);
let seed = Sha256::from_engine(unique_start).into_inner();
fn generate_channel_keys_id(&self, _inbound: bool, _channel_value_satoshis: u64, user_channel_id: u128) -> [u8; 32] {
let child_idx = self.channel_child_index.fetch_add(1, Ordering::AcqRel);
- assert!(child_idx <= core::u32::MAX as usize);
+ // `child_idx` is the only thing guaranteed to make each channel unique without a restart
+ // (though `user_channel_id` should help, depending on user behavior). If it manages to
+ // roll over, we may generate duplicate keys for two different channels, which could result
+ // in loss of funds. Because we only support 32-bit+ systems, assert that our `AtomicUsize`
+ // doesn't reach `u32::MAX`.
+ assert!(child_idx < core::u32::MAX as usize, "2^32 channels opened without restart");
let mut id = [0; 32];
id[0..4].copy_from_slice(&(child_idx as u32).to_be_bytes());
id[4..8].copy_from_slice(&self.starting_time_nanos.to_be_bytes());