Support responding to refunds with transient keys

[rust-lightning] / lightning / src / offers / refund.rs

diff --git a/lightning/src/offers/refund.rs b/lightning/src/offers/refund.rs
index 899586ba29d6b3875c225e91d40956c611a98793..f677a2a9cdb61fcdf5f5fe9f5389a6dba895512c 100644 (file)
--- a/lightning/src/offers/refund.rs
+++ b/lightning/src/offers/refund.rs
@@ -84,12 +84,12 @@ use crate::ln::PaymentHash;
 use crate::ln::features::InvoiceRequestFeatures;
 use crate::ln::inbound_payment::{ExpandedKey, IV_LEN, Nonce};
 use crate::ln::msgs::{DecodeError, MAX_VALUE_MSAT};
-use crate::offers::invoice::{BlindedPayInfo, ExplicitSigningPubkey, InvoiceBuilder};
+use crate::offers::invoice::{BlindedPayInfo, DerivedSigningPubkey, ExplicitSigningPubkey, InvoiceBuilder};
 use crate::offers::invoice_request::{InvoiceRequestTlvStream, InvoiceRequestTlvStreamRef};
 use crate::offers::offer::{OfferTlvStream, OfferTlvStreamRef};
 use crate::offers::parse::{Bech32Encode, ParseError, ParsedMessage, SemanticError};
 use crate::offers::payer::{PayerContents, PayerTlvStream, PayerTlvStreamRef};
-use crate::offers::signer::{Metadata, MetadataMaterial};
+use crate::offers::signer::{Metadata, MetadataMaterial, self};
 use crate::onion_message::BlindedPath;
 use crate::util::ser::{SeekReadable, WithoutLength, Writeable, Writer};
 use crate::util::string::PrintableString;
@@ -431,6 +431,51 @@ impl Refund {
                InvoiceBuilder::for_refund(self, payment_paths, created_at, payment_hash, signing_pubkey)
        }
 
+       /// Creates an [`InvoiceBuilder`] for the refund using the given required fields and that uses
+       /// derived signing keys to sign the [`Invoice`].
+       ///
+       /// See [`Refund::respond_with`] for further details.
+       ///
+       /// [`Invoice`]: crate::offers::invoice::Invoice
+       #[cfg(feature = "std")]
+       pub fn respond_using_derived_keys<ES: Deref>(
+               &self, payment_paths: Vec<(BlindedPath, BlindedPayInfo)>, payment_hash: PaymentHash,
+               expanded_key: &ExpandedKey, entropy_source: ES
+       ) -> Result<InvoiceBuilder<DerivedSigningPubkey>, SemanticError>
+       where
+               ES::Target: EntropySource,
+       {
+               let created_at = std::time::SystemTime::now()
+                       .duration_since(std::time::SystemTime::UNIX_EPOCH)
+                       .expect("SystemTime::now() should come after SystemTime::UNIX_EPOCH");
+
+               self.respond_using_derived_keys_no_std(
+                       payment_paths, payment_hash, created_at, expanded_key, entropy_source
+               )
+       }
+
+       /// Creates an [`InvoiceBuilder`] for the refund using the given required fields and that uses
+       /// derived signing keys to sign the [`Invoice`].
+       ///
+       /// See [`Refund::respond_with_no_std`] for further details.
+       ///
+       /// [`Invoice`]: crate::offers::invoice::Invoice
+       pub fn respond_using_derived_keys_no_std<ES: Deref>(
+               &self, payment_paths: Vec<(BlindedPath, BlindedPayInfo)>, payment_hash: PaymentHash,
+               created_at: core::time::Duration, expanded_key: &ExpandedKey, entropy_source: ES
+       ) -> Result<InvoiceBuilder<DerivedSigningPubkey>, SemanticError>
+       where
+               ES::Target: EntropySource,
+       {
+               if self.features().requires_unknown_bits() {
+                       return Err(SemanticError::UnknownRequiredFeatures);
+               }
+
+               let nonce = Nonce::from_entropy_source(entropy_source);
+               let keys = signer::derive_keys(nonce, expanded_key);
+               InvoiceBuilder::for_refund_using_keys(self, payment_paths, created_at, payment_hash, keys)
+       }
+
        #[cfg(test)]
        fn as_tlv_stream(&self) -> RefundTlvStreamRef {
                self.contents.as_tlv_stream()