Add a ChaCha20 utility for encrypting in place

[rust-lightning] / lightning / src / blinded_path / mod.rs

diff --git a/lightning/src/blinded_path/mod.rs b/lightning/src/blinded_path/mod.rs
index 6225f99869b9364c6fadd0f75f437bcafc95536d..89087a10cd414ac9fdeae4331490ef97e73666ea 100644 (file)
--- a/lightning/src/blinded_path/mod.rs
+++ b/lightning/src/blinded_path/mod.rs
@@ -9,6 +9,7 @@
 
 //! Creating blinded paths and related utilities live here.
 
+pub mod payment;
 pub(crate) mod message;
 pub(crate) mod utils;
 
@@ -40,13 +41,14 @@ pub struct BlindedPath {
        pub blinded_hops: Vec<BlindedHop>,
 }
 
-/// Used to construct the blinded hops portion of a blinded path. These hops cannot be identified
-/// by outside observers and thus can be used to hide the identity of the recipient.
+/// An encrypted payload and node id corresponding to a hop in a payment or onion message path, to
+/// be encoded in the sender's onion packet. These hops cannot be identified by outside observers
+/// and thus can be used to hide the identity of the recipient.
 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
 pub struct BlindedHop {
-       /// The blinded node id of this hop in a blinded path.
+       /// The blinded node id of this hop in a [`BlindedPath`].
        pub blinded_node_id: PublicKey,
-       /// The encrypted payload intended for this hop in a blinded path.
+       /// The encrypted payload intended for this hop in a [`BlindedPath`].
        // The node sending to this blinded path will later encode this payload into the onion packet for
        // this hop.
        pub encrypted_payload: Vec<u8>,
@@ -72,6 +74,27 @@ impl BlindedPath {
                        blinded_hops: message::blinded_hops(secp_ctx, node_pks, &blinding_secret).map_err(|_| ())?,
                })
        }
+
+       /// Create a blinded path for a payment, to be forwarded along `path`. The last node
+       /// in `path` will be the destination node.
+       ///
+       /// Errors if `path` is empty or a node id in `path` is invalid.
+       //  TODO: make all payloads the same size with padding + add dummy hops
+       pub fn new_for_payment<ES: EntropySource, T: secp256k1::Signing + secp256k1::Verification>(
+               intermediate_nodes: &[(PublicKey, payment::ForwardTlvs)], payee_node_id: PublicKey,
+               payee_tlvs: payment::ReceiveTlvs, entropy_source: &ES, secp_ctx: &Secp256k1<T>
+       ) -> Result<Self, ()> {
+               let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
+               let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
+
+               Ok(BlindedPath {
+                       introduction_node_id: intermediate_nodes.first().map_or(payee_node_id, |n| n.0),
+                       blinding_point: PublicKey::from_secret_key(secp_ctx, &blinding_secret),
+                       blinded_hops: payment::blinded_hops(
+                               secp_ctx, intermediate_nodes, payee_node_id, payee_tlvs, &blinding_secret
+                       ).map_err(|_| ())?,
+               })
+       }
 }
 
 impl Writeable for BlindedPath {