Add another ExpandedKey derivation for Offers

[rust-lightning] / lightning / src / ln / inbound_payment.rs

diff --git a/lightning/src/ln/inbound_payment.rs b/lightning/src/ln/inbound_payment.rs
index 0c6d6f2b804bccd8cfb651c24995bf4959998a91..058339cbc1d2451e385307fc0fa5dbc0bf96ab2a 100644 (file)
--- a/lightning/src/ln/inbound_payment.rs
+++ b/lightning/src/ln/inbound_payment.rs
@@ -19,7 +19,7 @@ use crate::ln::{PaymentHash, PaymentPreimage, PaymentSecret};
 use crate::ln::msgs;
 use crate::ln::msgs::MAX_VALUE_MSAT;
 use crate::util::chacha20::ChaCha20;
-use crate::util::crypto::hkdf_extract_expand_thrice;
+use crate::util::crypto::hkdf_extract_expand_4x;
 use crate::util::errors::APIError;
 use crate::util::logger::Logger;
 
@@ -48,6 +48,8 @@ pub struct ExpandedKey {
        /// The key used to authenticate a user-provided payment hash and metadata as previously
        /// registered with LDK.
        user_pmt_hash_key: [u8; 32],
+       /// The base key used to derive signing keys and authenticate messages for BOLT 12 Offers.
+       offers_base_key: [u8; 32],
 }
 
 impl ExpandedKey {
@@ -55,12 +57,13 @@ impl ExpandedKey {
        ///
        /// It is recommended to cache this value and not regenerate it for each new inbound payment.
        pub fn new(key_material: &KeyMaterial) -> ExpandedKey {
-               let (metadata_key, ldk_pmt_hash_key, user_pmt_hash_key) =
-                       hkdf_extract_expand_thrice(b"LDK Inbound Payment Key Expansion", &key_material.0);
+               let (metadata_key, ldk_pmt_hash_key, user_pmt_hash_key, offers_base_key) =
+                       hkdf_extract_expand_4x(b"LDK Inbound Payment Key Expansion", &key_material.0);
                Self {
                        metadata_key,
                        ldk_pmt_hash_key,
                        user_pmt_hash_key,
+                       offers_base_key,
                }
        }
 }