Rename Payment{Hash,Id} hmac creation/verification methods for offers.

We want to specify that these methods are only to be used in an outbound offers
payment context, because we'll be adding similar methods for the outbound async
payments context in upcoming commits.

Author: valentinewallace

lightning/src/ln/channelmanager.rs

@@ -420,7 +420,7 @@ pub trait Verification {
 	) -> Hmac<Sha256>;
 
 	/// Authenticates the data using an HMAC and a [`Nonce`] taken from an [`OffersContext`].
-	fn verify(
+	fn verify_for_offer_payment(
 		&self, hmac: Hmac<Sha256>, nonce: Nonce, expanded_key: &inbound_payment::ExpandedKey,
 	) -> Result<(), ()>;
 }
@@ -436,7 +436,7 @@ impl Verification for PaymentHash {
 
 	/// Authenticates the payment id using an HMAC and a [`Nonce`] taken from an
 	/// [`OffersContext::InboundPayment`].
-	fn verify(
+	fn verify_for_offer_payment(
 		&self, hmac: Hmac<Sha256>, nonce: Nonce, expanded_key: &inbound_payment::ExpandedKey,
 	) -> Result<(), ()> {
 		signer::verify_payment_hash(*self, hmac, nonce, expanded_key)
@@ -461,15 +461,15 @@ impl Verification for PaymentId {
 	fn hmac_for_offer_payment(
 		&self, nonce: Nonce, expanded_key: &inbound_payment::ExpandedKey,
 	) -> Hmac<Sha256> {
-		signer::hmac_for_payment_id(*self, nonce, expanded_key)
+		signer::hmac_for_offer_payment_id(*self, nonce, expanded_key)
 	}
 
 	/// Authenticates the payment id using an HMAC and a [`Nonce`] taken from an
 	/// [`OffersContext::OutboundPayment`].
-	fn verify(
+	fn verify_for_offer_payment(
 		&self, hmac: Hmac<Sha256>, nonce: Nonce, expanded_key: &inbound_payment::ExpandedKey,
 	) -> Result<(), ()> {
-		signer::verify_payment_id(*self, hmac, nonce, expanded_key)
+		signer::verify_offer_payment_id(*self, hmac, nonce, expanded_key)
 	}
 }
 
@@ -11144,7 +11144,7 @@ where
 			OffersMessage::StaticInvoice(invoice) => {
 				let payment_id = match context {
 					Some(OffersContext::OutboundPayment { payment_id, nonce, hmac: Some(hmac) }) => {
-						if payment_id.verify(hmac, nonce, expanded_key).is_err() {
+						if payment_id.verify_for_offer_payment(hmac, nonce, expanded_key).is_err() {
 							return None
 						}
 						payment_id
@@ -11157,7 +11157,7 @@ where
 			OffersMessage::InvoiceError(invoice_error) => {
 				let payment_hash = match context {
 					Some(OffersContext::InboundPayment { payment_hash, nonce, hmac }) => {
-						match payment_hash.verify(hmac, nonce, expanded_key) {
+						match payment_hash.verify_for_offer_payment(hmac, nonce, expanded_key) {
 							Ok(_) => Some(payment_hash),
 							Err(_) => None,
 						}
@@ -11170,7 +11170,7 @@ where
 
 				match context {
 					Some(OffersContext::OutboundPayment { payment_id, nonce, hmac: Some(hmac) }) => {
-						if let Ok(()) = payment_id.verify(hmac, nonce, expanded_key) {
+						if let Ok(()) = payment_id.verify_for_offer_payment(hmac, nonce, expanded_key) {
 							self.abandon_payment_with_reason(
 								payment_id, PaymentFailureReason::InvoiceRequestRejected,
 							);

lightning/src/offers/signer.rs

@@ -38,7 +38,7 @@ const WITHOUT_ENCRYPTED_PAYMENT_ID_HMAC_INPUT: &[u8; 16] = &[3; 16];
 const WITH_ENCRYPTED_PAYMENT_ID_HMAC_INPUT: &[u8; 16] = &[4; 16];
 
 // HMAC input for a `PaymentId`. The HMAC is used in `OffersContext::OutboundPayment`.
-const PAYMENT_ID_HMAC_INPUT: &[u8; 16] = &[5; 16];
+const OFFER_PAYMENT_ID_HMAC_INPUT: &[u8; 16] = &[5; 16];
 
 // HMAC input for a `PaymentHash`. The HMAC is used in `OffersContext::InboundPayment`.
 const PAYMENT_HASH_HMAC_INPUT: &[u8; 16] = &[6; 16];
@@ -399,23 +399,23 @@ fn hmac_for_message<'a>(
 	Ok(hmac)
 }
 
-pub(crate) fn hmac_for_payment_id(
+pub(crate) fn hmac_for_offer_payment_id(
 	payment_id: PaymentId, nonce: Nonce, expanded_key: &ExpandedKey,
 ) -> Hmac<Sha256> {
 	const IV_BYTES: &[u8; IV_LEN] = b"LDK Payment ID ~";
 	let mut hmac = expanded_key.hmac_for_offer();
 	hmac.input(IV_BYTES);
 	hmac.input(&nonce.0);
-	hmac.input(PAYMENT_ID_HMAC_INPUT);
+	hmac.input(OFFER_PAYMENT_ID_HMAC_INPUT);
 	hmac.input(&payment_id.0);
 
 	Hmac::from_engine(hmac)
 }
 
-pub(crate) fn verify_payment_id(
+pub(crate) fn verify_offer_payment_id(
 	payment_id: PaymentId, hmac: Hmac<Sha256>, nonce: Nonce, expanded_key: &ExpandedKey,
 ) -> Result<(), ()> {
-	if hmac_for_payment_id(payment_id, nonce, expanded_key) == hmac { Ok(()) } else { Err(()) }
+	if hmac_for_offer_payment_id(payment_id, nonce, expanded_key) == hmac { Ok(()) } else { Err(()) }
 }
 
 pub(crate) fn hmac_for_payment_hash(