diff --git a/fuzz/src/chanmon_consistency.rs b/fuzz/src/chanmon_consistency.rs
index 8b41c53a635..1439e11da6c 100644
--- a/fuzz/src/chanmon_consistency.rs
+++ b/fuzz/src/chanmon_consistency.rs
@@ -326,7 +326,7 @@ impl NodeSigner for KeyProvider {
 		Ok(SharedSecret::new(other_key, &node_secret))
 	}
 
-	fn get_inbound_payment_key(&self) -> ExpandedKey {
+	fn get_expanded_key(&self) -> ExpandedKey {
 		#[rustfmt::skip]
 		let random_bytes = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, self.node_secret[31]];
 		ExpandedKey::new(random_bytes)
diff --git a/fuzz/src/full_stack.rs b/fuzz/src/full_stack.rs
index 5281a933526..435bb24dae1 100644
--- a/fuzz/src/full_stack.rs
+++ b/fuzz/src/full_stack.rs
@@ -405,7 +405,7 @@ impl NodeSigner for KeyProvider {
 		Ok(SharedSecret::new(other_key, &node_secret))
 	}
 
-	fn get_inbound_payment_key(&self) -> ExpandedKey {
+	fn get_expanded_key(&self) -> ExpandedKey {
 		self.inbound_payment_key
 	}
 
diff --git a/fuzz/src/onion_message.rs b/fuzz/src/onion_message.rs
index a5782dacd42..fd3294fab28 100644
--- a/fuzz/src/onion_message.rs
+++ b/fuzz/src/onion_message.rs
@@ -228,7 +228,7 @@ impl NodeSigner for KeyProvider {
 		Ok(SharedSecret::new(other_key, &node_secret))
 	}
 
-	fn get_inbound_payment_key(&self) -> ExpandedKey {
+	fn get_expanded_key(&self) -> ExpandedKey {
 		unreachable!()
 	}
 
diff --git a/lightning/src/blinded_path/message.rs b/lightning/src/blinded_path/message.rs
index 0e3977ab68e..e9669e56240 100644
--- a/lightning/src/blinded_path/message.rs
+++ b/lightning/src/blinded_path/message.rs
@@ -11,6 +11,7 @@
 
 use bitcoin::secp256k1::{self, PublicKey, Secp256k1, SecretKey};
 
+use crate::offers::signer;
 #[allow(unused_imports)]
 use crate::prelude::*;
 
@@ -19,9 +20,9 @@ use crate::blinded_path::{BlindedHop, BlindedPath, Direction, IntroductionNode,
 use crate::crypto::streams::ChaChaPolyReadAdapter;
 use crate::io;
 use crate::io::Cursor;
-use crate::ln::channelmanager::PaymentId;
+use crate::ln::channelmanager::{PaymentId, Verification};
 use crate::ln::msgs::DecodeError;
-use crate::ln::onion_utils;
+use crate::ln::{inbound_payment, onion_utils};
 use crate::offers::nonce::Nonce;
 use crate::onion_message::packet::ControlTlvs;
 use crate::routing::gossip::{NodeId, ReadOnlyNetworkGraph};
@@ -258,6 +259,94 @@ pub(crate) struct ForwardTlvs {
 	pub(crate) next_blinding_override: Option<PublicKey>,
 }
 
+/// Represents a dummy TLV that can be used in a blinded path to extend the path length.
+/// The first dummy TLV is authenticated and contains an HMAC, while subsequent dummy TLVs are
+/// empty and do not contain any data. This allows for the path length to be extended without
+/// adding any additional data, while still ensuring that the path is legitimate and terminates
+/// in valid [`ReceiveTlvs`] data.
+pub(crate) enum DummyTlv {
+	/// The first dummy TLV, which contains an HMAC and is authenticated.
+	/// This TLV is used to ensure that the path is legitimate and terminates in valid
+	/// [`ReceiveTlvs`] data.
+	Primary(PrimaryDummyTlv),
+	/// Subsequent dummy TLVs, which are empty and do not contain any data.
+	/// These TLVs are used to extend the path length without adding any additional data.
+	Subsequent,
+}
+
+impl Writeable for DummyTlv {
+	fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
+		match self {
+			DummyTlv::Primary(primary) => primary.write(writer)?,
+			DummyTlv::Subsequent => {
+				// Subsequent dummy TLVs are empty, so we don't write anything.
+				// This is to ensure that the path length can be extended without
+				// adding any additional data.
+				encode_tlv_stream!(writer, {
+					(65541, (), required), // Represents that this is a Dummy Tlv variant
+				})
+			},
+		}
+		Ok(())
+	}
+}
+
+/// Represents the first dummy TLV in a blinded path, which is authenticated and contains an HMAC.
+/// These TLV are intended for the final node.
+///
+/// ## Authentication
+/// Authentication provides an additional layer of security, ensuring that the path is legitimate
+/// and terminates in valid [`ReceiveTlvs`] data. Verification begins with the first dummy hop and
+/// continues recursively until the final [`ReceiveTlvs`] is reached.
+///
+/// This prevents an attacker from crafting a bogus blinded path consisting solely of dummy tlv
+/// without any valid payload, which could otherwise waste resources through recursive
+/// processing — a potential vector for DoS-like attacks.
+pub(crate) struct PrimaryDummyTlv {
+	/// The dummy TLV that holds the empty data for the Dummy Hop.
+	pub(crate) dummy_tlv: UnauthenticatedDummyTlv,
+	/// An HMAC of `tlvs` along with a nonce used to construct it.
+	pub(crate) authentication: (Hmac<Sha256>, Nonce),
+}
+
+impl Writeable for PrimaryDummyTlv {
+	fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
+		encode_tlv_stream!(writer, {
+			(65539, self.authentication, required),
+			// The Some(()) represents that this is a Dummy Tlv variant
+			(65541, (), required),
+		});
+
+		Ok(())
+	}
+}
+
+/// A blank struct, representing a dummy TLV prior to authentication.
+///
+/// For more details, see [`PrimaryDummyTlv`].
+pub(crate) struct UnauthenticatedDummyTlv {}
+
+impl Writeable for UnauthenticatedDummyTlv {
+	fn write<W: Writer>(&self, _writer: &mut W) -> Result<(), io::Error> {
+		Ok(())
+	}
+}
+
+impl Verification for UnauthenticatedDummyTlv {
+	/// Constructs an HMAC to include in [`OffersContext`] for the data along with the given
+	/// [`Nonce`].
+	fn hmac_data(&self, nonce: Nonce, expanded_key: &inbound_payment::ExpandedKey) -> Hmac<Sha256> {
+		signer::hmac_for_dummy_tlv(self, nonce, expanded_key)
+	}
+
+	/// Authenticates the data using an HMAC and a [`Nonce`] taken from an [`OffersContext`].
+	fn verify_data(
+		&self, hmac: Hmac<Sha256>, nonce: Nonce, expanded_key: &inbound_payment::ExpandedKey,
+	) -> Result<(), ()> {
+		signer::verify_dummy_tlv(self, hmac, nonce, expanded_key)
+	}
+}
+
 /// Similar to [`ForwardTlvs`], but these TLVs are for the final node.
 pub(crate) struct ReceiveTlvs {
 	/// If `context` is `Some`, it is used to identify the blinded path that this onion message is
diff --git a/lightning/src/blinded_path/payment.rs b/lightning/src/blinded_path/payment.rs
index f015886933a..ae26d51b1f2 100644
--- a/lightning/src/blinded_path/payment.rs
+++ b/lightning/src/blinded_path/payment.rs
@@ -351,10 +351,7 @@ impl UnauthenticatedReceiveTlvs {
 	/// Creates an authenticated [`ReceiveTlvs`], which includes an HMAC and the provide [`Nonce`]
 	/// that can be use later to verify it authenticity.
 	pub fn authenticate(self, nonce: Nonce, expanded_key: &ExpandedKey) -> ReceiveTlvs {
-		ReceiveTlvs {
-			authentication: (self.hmac_for_offer_payment(nonce, expanded_key), nonce),
-			tlvs: self,
-		}
+		ReceiveTlvs { authentication: (self.hmac_data(nonce, expanded_key), nonce), tlvs: self }
 	}
 }
 
diff --git a/lightning/src/ln/async_payments_tests.rs b/lightning/src/ln/async_payments_tests.rs
index a956f2ebae2..9277775b38d 100644
--- a/lightning/src/ln/async_payments_tests.rs
+++ b/lightning/src/ln/async_payments_tests.rs
@@ -668,7 +668,7 @@ fn amount_doesnt_match_invreq() {
 			valid_invreq = Some(invoice_request.clone());
 			*invoice_request = offer
 				.request_invoice(
-					&nodes[0].keys_manager.get_inbound_payment_key(),
+					&nodes[0].keys_manager.get_expanded_key(),
 					Nonce::from_entropy_source(nodes[0].keys_manager),
 					&secp_ctx,
 					payment_id,
diff --git a/lightning/src/ln/blinded_payment_tests.rs b/lightning/src/ln/blinded_payment_tests.rs
index 18a1089d647..43de09a936c 100644
--- a/lightning/src/ln/blinded_payment_tests.rs
+++ b/lightning/src/ln/blinded_payment_tests.rs
@@ -83,7 +83,7 @@ pub fn blinded_payment_path(
 	};
 
 	let nonce = Nonce([42u8; 16]);
-	let expanded_key = keys_manager.get_inbound_payment_key();
+	let expanded_key = keys_manager.get_expanded_key();
 	let payee_tlvs = payee_tlvs.authenticate(nonce, &expanded_key);
 
 	let mut secp_ctx = Secp256k1::new();
@@ -168,7 +168,7 @@ fn do_one_hop_blinded_path(success: bool) {
 		payment_context: PaymentContext::Bolt12Refund(Bolt12RefundContext {}),
 	};
 	let nonce = Nonce([42u8; 16]);
-	let expanded_key = chanmon_cfgs[1].keys_manager.get_inbound_payment_key();
+	let expanded_key = chanmon_cfgs[1].keys_manager.get_expanded_key();
 	let payee_tlvs = payee_tlvs.authenticate(nonce, &expanded_key);
 
 	let mut secp_ctx = Secp256k1::new();
@@ -222,7 +222,7 @@ fn mpp_to_one_hop_blinded_path() {
 		payment_context: PaymentContext::Bolt12Refund(Bolt12RefundContext {}),
 	};
 	let nonce = Nonce([42u8; 16]);
-	let expanded_key = chanmon_cfgs[3].keys_manager.get_inbound_payment_key();
+	let expanded_key = chanmon_cfgs[3].keys_manager.get_expanded_key();
 	let payee_tlvs = payee_tlvs.authenticate(nonce, &expanded_key);
 	let blinded_path = BlindedPaymentPath::new(
 		&[], nodes[3].node.get_our_node_id(), payee_tlvs, u64::MAX, TEST_FINAL_CLTV as u16,
@@ -1342,7 +1342,7 @@ fn custom_tlvs_to_blinded_path() {
 		payment_context: PaymentContext::Bolt12Refund(Bolt12RefundContext {}),
 	};
 	let nonce = Nonce([42u8; 16]);
-	let expanded_key = chanmon_cfgs[1].keys_manager.get_inbound_payment_key();
+	let expanded_key = chanmon_cfgs[1].keys_manager.get_expanded_key();
 	let payee_tlvs = payee_tlvs.authenticate(nonce, &expanded_key);
 	let mut secp_ctx = Secp256k1::new();
 	let blinded_path = BlindedPaymentPath::new(
@@ -1396,7 +1396,7 @@ fn fails_receive_tlvs_authentication() {
 		payment_context: PaymentContext::Bolt12Refund(Bolt12RefundContext {}),
 	};
 	let nonce = Nonce([42u8; 16]);
-	let expanded_key = chanmon_cfgs[1].keys_manager.get_inbound_payment_key();
+	let expanded_key = chanmon_cfgs[1].keys_manager.get_expanded_key();
 	let payee_tlvs = payee_tlvs.authenticate(nonce, &expanded_key);
 
 	let mut secp_ctx = Secp256k1::new();
@@ -1622,7 +1622,7 @@ fn route_blinding_spec_test_vector() {
 			}
 			Ok(SharedSecret::new(other_key, &node_secret))
 		}
-		fn get_inbound_payment_key(&self) -> ExpandedKey { unreachable!() }
+		fn get_expanded_key(&self) -> ExpandedKey { unreachable!() }
 		fn get_node_id(&self, _recipient: Recipient) -> Result<PublicKey, ()> { unreachable!() }
 		fn sign_invoice(
 			&self, _invoice: &RawBolt11Invoice, _recipient: Recipient,
@@ -1931,7 +1931,7 @@ fn test_trampoline_inbound_payment_decoding() {
 			}
 			Ok(SharedSecret::new(other_key, &node_secret))
 		}
-		fn get_inbound_payment_key(&self) -> ExpandedKey { unreachable!() }
+		fn get_expanded_key(&self) -> ExpandedKey { unreachable!() }
 		fn get_node_id(&self, _recipient: Recipient) -> Result<PublicKey, ()> { unreachable!() }
 		fn sign_invoice(
 			&self, _invoice: &RawBolt11Invoice, _recipient: Recipient,
@@ -2016,7 +2016,7 @@ fn do_test_trampoline_single_hop_receive(success: bool) {
 		};
 
 		let nonce = Nonce([42u8; 16]);
-		let expanded_key = nodes[2].keys_manager.get_inbound_payment_key();
+		let expanded_key = nodes[2].keys_manager.get_expanded_key();
 		let payee_tlvs = payee_tlvs.authenticate(nonce, &expanded_key);
 		let carol_unblinded_tlvs = payee_tlvs.encode();
 
diff --git a/lightning/src/ln/channelmanager.rs b/lightning/src/ln/channelmanager.rs
index 170d8261d5a..71285938c6b 100644
--- a/lightning/src/ln/channelmanager.rs
+++ b/lightning/src/ln/channelmanager.rs
@@ -256,7 +256,7 @@ pub enum PendingHTLCRouting {
 		requires_blinded_error: bool,
 		/// Set if we are receiving a keysend to a blinded path, meaning we created the
 		/// [`PaymentSecret`] and should verify it using our
-		/// [`NodeSigner::get_inbound_payment_key`].
+		/// [`NodeSigner::get_expanded_key`].
 		has_recipient_created_payment_secret: bool,
 		/// The [`InvoiceRequest`] associated with the [`Offer`] corresponding to this payment.
 		invoice_request: Option<InvoiceRequest>,
@@ -475,12 +475,12 @@ impl Ord for ClaimableHTLC {
 pub trait Verification {
 	/// Constructs an HMAC to include in [`OffersContext`] for the data along with the given
 	/// [`Nonce`].
-	fn hmac_for_offer_payment(
+	fn hmac_data(
 		&self, nonce: Nonce, expanded_key: &inbound_payment::ExpandedKey,
 	) -> Hmac<Sha256>;
 
 	/// Authenticates the data using an HMAC and a [`Nonce`] taken from an [`OffersContext`].
-	fn verify_for_offer_payment(
+	fn verify_data(
 		&self, hmac: Hmac<Sha256>, nonce: Nonce, expanded_key: &inbound_payment::ExpandedKey,
 	) -> Result<(), ()>;
 }
@@ -488,7 +488,7 @@ pub trait Verification {
 impl Verification for PaymentHash {
 	/// Constructs an HMAC to include in [`OffersContext::InboundPayment`] for the payment hash
 	/// along with the given [`Nonce`].
-	fn hmac_for_offer_payment(
+	fn hmac_data(
 		&self, nonce: Nonce, expanded_key: &inbound_payment::ExpandedKey,
 	) -> Hmac<Sha256> {
 		signer::hmac_for_payment_hash(*self, nonce, expanded_key)
@@ -496,7 +496,7 @@ impl Verification for PaymentHash {
 
 	/// Authenticates the payment id using an HMAC and a [`Nonce`] taken from an
 	/// [`OffersContext::InboundPayment`].
-	fn verify_for_offer_payment(
+	fn verify_data(
 		&self, hmac: Hmac<Sha256>, nonce: Nonce, expanded_key: &inbound_payment::ExpandedKey,
 	) -> Result<(), ()> {
 		signer::verify_payment_hash(*self, hmac, nonce, expanded_key)
@@ -504,13 +504,13 @@ impl Verification for PaymentHash {
 }
 
 impl Verification for UnauthenticatedReceiveTlvs {
-	fn hmac_for_offer_payment(
+	fn hmac_data(
 		&self, nonce: Nonce, expanded_key: &inbound_payment::ExpandedKey,
 	) -> Hmac<Sha256> {
 		signer::hmac_for_payment_tlvs(self, nonce, expanded_key)
 	}
 
-	fn verify_for_offer_payment(
+	fn verify_data(
 		&self, hmac: Hmac<Sha256>, nonce: Nonce, expanded_key: &inbound_payment::ExpandedKey,
 	) -> Result<(), ()> {
 		signer::verify_payment_tlvs(self, hmac, nonce, expanded_key)
@@ -550,7 +550,7 @@ impl PaymentId {
 impl Verification for PaymentId {
 	/// Constructs an HMAC to include in [`OffersContext::OutboundPayment`] for the payment id
 	/// along with the given [`Nonce`].
-	fn hmac_for_offer_payment(
+	fn hmac_data(
 		&self, nonce: Nonce, expanded_key: &inbound_payment::ExpandedKey,
 	) -> Hmac<Sha256> {
 		signer::hmac_for_offer_payment_id(*self, nonce, expanded_key)
@@ -558,7 +558,7 @@ impl Verification for PaymentId {
 
 	/// Authenticates the payment id using an HMAC and a [`Nonce`] taken from an
 	/// [`OffersContext::OutboundPayment`].
-	fn verify_for_offer_payment(
+	fn verify_data(
 		&self, hmac: Hmac<Sha256>, nonce: Nonce, expanded_key: &inbound_payment::ExpandedKey,
 	) -> Result<(), ()> {
 		signer::verify_offer_payment_id(*self, hmac, nonce, expanded_key)
@@ -3576,7 +3576,7 @@ where
 	) -> Self {
 		let mut secp_ctx = Secp256k1::new();
 		secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
-		let expanded_inbound_key = node_signer.get_inbound_payment_key();
+		let expanded_inbound_key = node_signer.get_expanded_key();
 		ChannelManager {
 			default_configuration: config.clone(),
 			chain_hash: ChainHash::using_genesis_block(params.network),
@@ -10560,7 +10560,7 @@ where
 		};
 		let invoice_request = builder.build_and_sign()?;
 
-		let hmac = payment_id.hmac_for_offer_payment(nonce, expanded_key);
+		let hmac = payment_id.hmac_data(nonce, expanded_key);
 		let context = MessageContext::Offers(
 			OffersContext::OutboundPayment { payment_id, nonce, hmac: Some(hmac) }
 		);
@@ -10664,7 +10664,7 @@ where
 				let invoice = builder.allow_mpp().build_and_sign(secp_ctx)?;
 
 				let nonce = Nonce::from_entropy_source(entropy);
-				let hmac = payment_hash.hmac_for_offer_payment(nonce, expanded_key);
+				let hmac = payment_hash.hmac_data(nonce, expanded_key);
 				let context = MessageContext::Offers(OffersContext::InboundPayment {
 					payment_hash: invoice.payment_hash(), nonce, hmac
 				});
@@ -12444,7 +12444,7 @@ where
 			.release_invoice_requests_awaiting_invoice()
 		{
 			let RetryableInvoiceRequest { invoice_request, nonce, .. } = retryable_invoice_request;
-			let hmac = payment_id.hmac_for_offer_payment(nonce, &self.inbound_payment_key);
+			let hmac = payment_id.hmac_data(nonce, &self.inbound_payment_key);
 			let context = MessageContext::Offers(OffersContext::OutboundPayment {
 				payment_id,
 				nonce,
@@ -12627,7 +12627,7 @@ where
 				match response {
 					Ok(invoice) => {
 						let nonce = Nonce::from_entropy_source(&*self.entropy_source);
-						let hmac = payment_hash.hmac_for_offer_payment(nonce, expanded_key);
+						let hmac = payment_hash.hmac_data(nonce, expanded_key);
 						let context = MessageContext::Offers(OffersContext::InboundPayment { payment_hash, nonce, hmac });
 						Some((OffersMessage::Invoice(invoice), responder.respond_with_reply_path(context)))
 					},
@@ -12664,7 +12664,7 @@ where
 			OffersMessage::StaticInvoice(invoice) => {
 				let payment_id = match context {
 					Some(OffersContext::OutboundPayment { payment_id, nonce, hmac: Some(hmac) }) => {
-						if payment_id.verify_for_offer_payment(hmac, nonce, expanded_key).is_err() {
+						if payment_id.verify_data(hmac, nonce, expanded_key).is_err() {
 							return None
 						}
 						payment_id
@@ -12677,7 +12677,7 @@ where
 			OffersMessage::InvoiceError(invoice_error) => {
 				let payment_hash = match context {
 					Some(OffersContext::InboundPayment { payment_hash, nonce, hmac }) => {
-						match payment_hash.verify_for_offer_payment(hmac, nonce, expanded_key) {
+						match payment_hash.verify_data(hmac, nonce, expanded_key) {
 							Ok(_) => Some(payment_hash),
 							Err(_) => None,
 						}
@@ -12690,7 +12690,7 @@ where
 
 				match context {
 					Some(OffersContext::OutboundPayment { payment_id, nonce, hmac: Some(hmac) }) => {
-						if let Ok(()) = payment_id.verify_for_offer_payment(hmac, nonce, expanded_key) {
+						if let Ok(()) = payment_id.verify_data(hmac, nonce, expanded_key) {
 							self.abandon_payment_with_reason(
 								payment_id, PaymentFailureReason::InvoiceRequestRejected,
 							);
@@ -14569,7 +14569,7 @@ where
 			}, None));
 		}
 
-		let expanded_inbound_key = args.node_signer.get_inbound_payment_key();
+		let expanded_inbound_key = args.node_signer.get_expanded_key();
 
 		let mut claimable_payments = hash_map_with_capacity(claimable_htlcs_list.len());
 		if let Some(purposes) = claimable_htlc_purposes {
diff --git a/lightning/src/ln/inbound_payment.rs b/lightning/src/ln/inbound_payment.rs
index 53b212428ca..6a0b52d40b5 100644
--- a/lightning/src/ln/inbound_payment.rs
+++ b/lightning/src/ln/inbound_payment.rs
@@ -37,9 +37,9 @@ const AMT_MSAT_LEN: usize = 8;
 // retrieve said payment type bits.
 const METHOD_TYPE_OFFSET: usize = 5;
 
-/// A set of keys that were HKDF-expanded. Returned by [`NodeSigner::get_inbound_payment_key`].
+/// A set of keys that were HKDF-expanded. Returned by [`NodeSigner::get_expanded_key`].
 ///
-/// [`NodeSigner::get_inbound_payment_key`]: crate::sign::NodeSigner::get_inbound_payment_key
+/// [`NodeSigner::get_expanded_key`]: crate::sign::NodeSigner::get_expanded_key
 #[derive(Hash, Copy, Clone, PartialEq, Eq, Debug)]
 pub struct ExpandedKey {
 	/// The key used to encrypt the bytes containing the payment metadata (i.e. the amount and
@@ -133,7 +133,7 @@ fn min_final_cltv_expiry_delta_from_metadata(bytes: [u8; METADATA_LEN]) -> u16 {
 /// `ChannelManager` is required. Useful for generating invoices for [phantom node payments] without
 /// a `ChannelManager`.
 ///
-/// `keys` is generated by calling [`NodeSigner::get_inbound_payment_key`]. It is recommended to
+/// `keys` is generated by calling [`NodeSigner::get_expanded_key`]. It is recommended to
 /// cache this value and not regenerate it for each new inbound payment.
 ///
 /// `current_time` is a Unix timestamp representing the current time.
@@ -142,7 +142,7 @@ fn min_final_cltv_expiry_delta_from_metadata(bytes: [u8; METADATA_LEN]) -> u16 {
 /// on versions of LDK prior to 0.0.114.
 ///
 /// [phantom node payments]: crate::sign::PhantomKeysManager
-/// [`NodeSigner::get_inbound_payment_key`]: crate::sign::NodeSigner::get_inbound_payment_key
+/// [`NodeSigner::get_expanded_key`]: crate::sign::NodeSigner::get_expanded_key
 pub fn create<ES: Deref>(
 	keys: &ExpandedKey, min_value_msat: Option<u64>, invoice_expiry_delta_secs: u32,
 	entropy_source: &ES, current_time: u64, min_final_cltv_expiry_delta: Option<u16>,
@@ -322,7 +322,7 @@ fn construct_payment_secret(
 /// For payments including a custom `min_final_cltv_expiry_delta`, the metadata is constructed as:
 ///   payment method (3 bits) || payment amount (8 bytes - 3 bits) || min_final_cltv_expiry_delta (2 bytes) || expiry (6 bytes)
 ///
-/// In both cases the result is then encrypted using a key derived from [`NodeSigner::get_inbound_payment_key`].
+/// In both cases the result is then encrypted using a key derived from [`NodeSigner::get_expanded_key`].
 ///
 /// Then on payment receipt, we verify in this method that the payment preimage and payment secret
 /// match what was constructed.
@@ -343,7 +343,7 @@ fn construct_payment_secret(
 ///
 /// See [`ExpandedKey`] docs for more info on the individual keys used.
 ///
-/// [`NodeSigner::get_inbound_payment_key`]: crate::sign::NodeSigner::get_inbound_payment_key
+/// [`NodeSigner::get_expanded_key`]: crate::sign::NodeSigner::get_expanded_key
 /// [`create_inbound_payment`]: crate::ln::channelmanager::ChannelManager::create_inbound_payment
 /// [`create_inbound_payment_for_hash`]: crate::ln::channelmanager::ChannelManager::create_inbound_payment_for_hash
 pub(super) fn verify<L: Deref>(
diff --git a/lightning/src/ln/invoice_utils.rs b/lightning/src/ln/invoice_utils.rs
index f2e8284a617..876f5eccb27 100644
--- a/lightning/src/ln/invoice_utils.rs
+++ b/lightning/src/ln/invoice_utils.rs
@@ -195,7 +195,7 @@ where
 		},
 	};
 
-	let keys = node_signer.get_inbound_payment_key();
+	let keys = node_signer.get_expanded_key();
 	let (payment_hash, payment_secret) = if let Some(payment_hash) = payment_hash {
 		let payment_secret = create_from_hash(
 			&keys,
diff --git a/lightning/src/ln/max_payment_path_len_tests.rs b/lightning/src/ln/max_payment_path_len_tests.rs
index 95a1fbaaa10..8fce1f20e3b 100644
--- a/lightning/src/ln/max_payment_path_len_tests.rs
+++ b/lightning/src/ln/max_payment_path_len_tests.rs
@@ -173,7 +173,7 @@ fn one_hop_blinded_path_with_custom_tlv() {
 		payment_context: PaymentContext::Bolt12Refund(Bolt12RefundContext {}),
 	};
 	let nonce = Nonce([42u8; 16]);
-	let expanded_key = chanmon_cfgs[2].keys_manager.get_inbound_payment_key();
+	let expanded_key = chanmon_cfgs[2].keys_manager.get_expanded_key();
 	let payee_tlvs = payee_tlvs.authenticate(nonce, &expanded_key);
 	let mut secp_ctx = Secp256k1::new();
 	let blinded_path = BlindedPaymentPath::new(
diff --git a/lightning/src/ln/msgs.rs b/lightning/src/ln/msgs.rs
index 2e9c3b90957..1c19c3a15d5 100644
--- a/lightning/src/ln/msgs.rs
+++ b/lightning/src/ln/msgs.rs
@@ -3443,8 +3443,8 @@ where
 				},
 				ChaChaPolyReadAdapter { readable: BlindedPaymentTlvs::Receive(receive_tlvs) } => {
 					let ReceiveTlvs { tlvs, authentication: (hmac, nonce) } = receive_tlvs;
-					let expanded_key = node_signer.get_inbound_payment_key();
-					if tlvs.verify_for_offer_payment(hmac, nonce, &expanded_key).is_err() {
+					let expanded_key = node_signer.get_expanded_key();
+					if tlvs.verify_data(hmac, nonce, &expanded_key).is_err() {
 						return Err(DecodeError::InvalidValue);
 					}
 
@@ -3595,8 +3595,8 @@ where
 					readable: BlindedTrampolineTlvs::Receive(receive_tlvs),
 				} => {
 					let ReceiveTlvs { tlvs, authentication: (hmac, nonce) } = receive_tlvs;
-					let expanded_key = node_signer.get_inbound_payment_key();
-					if tlvs.verify_for_offer_payment(hmac, nonce, &expanded_key).is_err() {
+					let expanded_key = node_signer.get_expanded_key();
+					if tlvs.verify_data(hmac, nonce, &expanded_key).is_err() {
 						return Err(DecodeError::InvalidValue);
 					}
 
diff --git a/lightning/src/ln/offers_tests.rs b/lightning/src/ln/offers_tests.rs
index f8649111a0c..bc9abd59914 100644
--- a/lightning/src/ln/offers_tests.rs
+++ b/lightning/src/ln/offers_tests.rs
@@ -2223,7 +2223,7 @@ fn fails_paying_invoice_with_unknown_required_features() {
 	let payment_paths = invoice.payment_paths().to_vec();
 	let payment_hash = invoice.payment_hash();
 
-	let expanded_key = alice.keys_manager.get_inbound_payment_key();
+	let expanded_key = alice.keys_manager.get_expanded_key();
 	let secp_ctx = Secp256k1::new();
 
 	let created_at = alice.node.duration_since_epoch();
diff --git a/lightning/src/offers/signer.rs b/lightning/src/offers/signer.rs
index 329b90d2076..82b5b6a3f78 100644
--- a/lightning/src/offers/signer.rs
+++ b/lightning/src/offers/signer.rs
@@ -9,6 +9,7 @@
 
 //! Utilities for signing offer messages and verifying metadata.
 
+use crate::blinded_path::message::UnauthenticatedDummyTlv;
 use crate::blinded_path::payment::UnauthenticatedReceiveTlvs;
 use crate::ln::channelmanager::PaymentId;
 use crate::ln::inbound_payment::{ExpandedKey, IV_LEN};
@@ -570,3 +571,26 @@ pub(crate) fn verify_held_htlc_available_context(
 		Err(())
 	}
 }
+
+pub(crate) fn hmac_for_dummy_tlv(
+	tlvs: &UnauthenticatedDummyTlv, nonce: Nonce, expanded_key: &ExpandedKey,
+) -> Hmac<Sha256> {
+	const IV_BYTES: &[u8; IV_LEN] = b"LDK Msgs Dummies";
+	let mut hmac = expanded_key.hmac_for_offer();
+	hmac.input(IV_BYTES);
+	hmac.input(&nonce.0);
+	hmac.input(PAYMENT_TLVS_HMAC_INPUT);
+	tlvs.write(&mut hmac).unwrap();
+
+	Hmac::from_engine(hmac)
+}
+
+pub(crate) fn verify_dummy_tlv(
+	tlvs: &UnauthenticatedDummyTlv, hmac: Hmac<Sha256>, nonce: Nonce, expanded_key: &ExpandedKey,
+) -> Result<(), ()> {
+	if hmac_for_dummy_tlv(tlvs, nonce, expanded_key) == hmac {
+		Ok(())
+	} else {
+		Err(())
+	}
+}
diff --git a/lightning/src/onion_message/packet.rs b/lightning/src/onion_message/packet.rs
index 632cbc9c8a3..d3e6e204113 100644
--- a/lightning/src/onion_message/packet.rs
+++ b/lightning/src/onion_message/packet.rs
@@ -17,7 +17,10 @@ use super::async_payments::AsyncPaymentsMessage;
 use super::dns_resolution::DNSResolverMessage;
 use super::messenger::CustomOnionMessageHandler;
 use super::offers::OffersMessage;
-use crate::blinded_path::message::{BlindedMessagePath, ForwardTlvs, NextMessageHop, ReceiveTlvs};
+use crate::blinded_path::message::{
+	BlindedMessagePath, DummyTlv, ForwardTlvs, NextMessageHop, PrimaryDummyTlv, ReceiveTlvs,
+	UnauthenticatedDummyTlv,
+};
 use crate::crypto::streams::{ChaChaPolyReadAdapter, ChaChaPolyWriteAdapter};
 use crate::ln::msgs::DecodeError;
 use crate::ln::onion_utils;
@@ -111,6 +114,8 @@ impl LengthReadable for Packet {
 pub(super) enum Payload<T: OnionMessageContents> {
 	/// This payload is for an intermediate hop.
 	Forward(ForwardControlTlvs),
+	/// This payload is dummy, and is inteded to be peeled.
+	Dummy(DummyControlTlvs),
 	/// This payload is for the final hop.
 	Receive { control_tlvs: ReceiveControlTlvs, reply_path: Option<BlindedMessagePath>, message: T },
 }
@@ -204,6 +209,11 @@ pub(super) enum ForwardControlTlvs {
 	Unblinded(ForwardTlvs),
 }
 
+pub(super) enum DummyControlTlvs {
+	/// See [`ForwardControlTlvs::Unblinded`]
+	Unblinded(DummyTlv),
+}
+
 /// Receive control TLVs in their blinded and unblinded form.
 pub(super) enum ReceiveControlTlvs {
 	/// See [`ForwardControlTlvs::Blinded`].
@@ -234,6 +244,10 @@ impl<T: OnionMessageContents> Writeable for (Payload<T>, [u8; 32]) {
 				let write_adapter = ChaChaPolyWriteAdapter::new(self.1, &control_tlvs);
 				_encode_varint_length_prefixed_tlv!(w, { (4, write_adapter, required) })
 			},
+			Payload::Dummy(DummyControlTlvs::Unblinded(control_tlvs)) => {
+				let write_adapter = ChaChaPolyWriteAdapter::new(self.1, &control_tlvs);
+				_encode_varint_length_prefixed_tlv!(w, { (4, write_adapter, required) })
+			},
 			Payload::Receive {
 				control_tlvs: ReceiveControlTlvs::Unblinded(control_tlvs),
 				reply_path,
@@ -310,6 +324,9 @@ impl<H: CustomOnionMessageHandler + ?Sized, L: Logger + ?Sized> ReadableArgs<(Sh
 				}
 				Ok(Payload::Forward(ForwardControlTlvs::Unblinded(tlvs)))
 			},
+			Some(ChaChaPolyReadAdapter { readable: ControlTlvs::Dummy(tlvs) }) => {
+				Ok(Payload::Dummy(DummyControlTlvs::Unblinded(tlvs)))
+			},
 			Some(ChaChaPolyReadAdapter { readable: ControlTlvs::Receive(tlvs) }) => {
 				Ok(Payload::Receive {
 					control_tlvs: ReceiveControlTlvs::Unblinded(tlvs),
@@ -328,6 +345,8 @@ impl<H: CustomOnionMessageHandler + ?Sized, L: Logger + ?Sized> ReadableArgs<(Sh
 pub(crate) enum ControlTlvs {
 	/// This onion message is intended to be forwarded.
 	Forward(ForwardTlvs),
+	/// This onion message is a dummy, and is intended to be peeled.
+	Dummy(DummyTlv),
 	/// This onion message is intended to be received.
 	Receive(ReceiveTlvs),
 }
@@ -343,6 +362,8 @@ impl Readable for ControlTlvs {
 			(4, next_node_id, option),
 			(8, next_blinding_override, option),
 			(65537, context, option),
+			(65539, authentication, option),
+			(65541, dummy_tlv, option),
 		});
 
 		let next_hop = match (short_channel_id, next_node_id) {
@@ -352,18 +373,18 @@ impl Readable for ControlTlvs {
 			(None, None) => None,
 		};
 
-		let valid_fwd_fmt = next_hop.is_some();
-		let valid_recv_fmt = next_hop.is_none() && next_blinding_override.is_none();
-
-		let payload_fmt = if valid_fwd_fmt {
-			ControlTlvs::Forward(ForwardTlvs {
-				next_hop: next_hop.unwrap(),
-				next_blinding_override,
-			})
-		} else if valid_recv_fmt {
-			ControlTlvs::Receive(ReceiveTlvs { context })
-		} else {
-			return Err(DecodeError::InvalidValue);
+		let payload_fmt = match (dummy_tlv, next_hop, next_blinding_override, authentication) {
+			(None, Some(hop), _, None) => {
+				ControlTlvs::Forward(ForwardTlvs { next_hop: hop, next_blinding_override })
+			},
+			(None, None, None, None) => ControlTlvs::Receive(ReceiveTlvs { context }),
+			(Some(()), None, None, Some(auth)) => {
+				let tlv =
+					PrimaryDummyTlv { dummy_tlv: UnauthenticatedDummyTlv {}, authentication: auth };
+				ControlTlvs::Dummy(DummyTlv::Primary(tlv))
+			},
+			(Some(()), None, None, None) => ControlTlvs::Dummy(DummyTlv::Subsequent),
+			_ => return Err(DecodeError::InvalidValue),
 		};
 
 		Ok(payload_fmt)
@@ -374,6 +395,7 @@ impl Writeable for ControlTlvs {
 	fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 		match self {
 			Self::Forward(tlvs) => tlvs.write(w),
+			Self::Dummy(tlvs) => tlvs.write(w),
 			Self::Receive(tlvs) => tlvs.write(w),
 		}
 	}
diff --git a/lightning/src/sign/mod.rs b/lightning/src/sign/mod.rs
index f35a407634a..57af75d1ef1 100644
--- a/lightning/src/sign/mod.rs
+++ b/lightning/src/sign/mod.rs
@@ -820,19 +820,24 @@ pub trait EntropySource {
 
 /// A trait that can handle cryptographic operations at the scope level of a node.
 pub trait NodeSigner {
-	/// Get the [`ExpandedKey`] for use in encrypting and decrypting inbound payment data.
+	/// Get the [`ExpandedKey`] which provides cryptographic material for various Lightning Network operations.
+	///
+	/// This key set is used for:
+	/// - Encrypting and decrypting inbound payment metadata
+	/// - Authenticating payment hashes (both LDK-provided and user-provided)
+	/// - Supporting BOLT 12 Offers functionality (signing and encryption)
+	/// - Authenticating spontaneous payments' metadata
 	///
 	/// If the implementor of this trait supports [phantom node payments], then every node that is
 	/// intended to be included in the phantom invoice route hints must return the same value from
 	/// this method.
-	// This is because LDK avoids storing inbound payment data by encrypting payment data in the
-	// payment hash and/or payment secret, therefore for a payment to be receivable by multiple
-	// nodes, they must share the key that encrypts this payment data.
 	///
-	/// This method must return the same value each time it is called.
+	/// This method must return the same value each time it is called, as LDK avoids storing inbound
+	/// payment data by encrypting it in the payment hash and/or payment secret. Consistency is also
+	/// required for signature and encryption verification in Offers and spontaneous payments.
 	///
 	/// [phantom node payments]: PhantomKeysManager
-	fn get_inbound_payment_key(&self) -> ExpandedKey;
+	fn get_expanded_key(&self) -> ExpandedKey;
 
 	/// Get node id based on the provided [`Recipient`].
 	///
@@ -2113,7 +2118,7 @@ impl NodeSigner for KeysManager {
 		Ok(SharedSecret::new(other_key, &node_secret))
 	}
 
-	fn get_inbound_payment_key(&self) -> ExpandedKey {
+	fn get_expanded_key(&self) -> ExpandedKey {
 		self.inbound_payment_key.clone()
 	}
 
@@ -2274,7 +2279,7 @@ impl NodeSigner for PhantomKeysManager {
 		Ok(SharedSecret::new(other_key, &node_secret))
 	}
 
-	fn get_inbound_payment_key(&self) -> ExpandedKey {
+	fn get_expanded_key(&self) -> ExpandedKey {
 		self.inbound_payment_key.clone()
 	}
 
diff --git a/lightning/src/util/dyn_signer.rs b/lightning/src/util/dyn_signer.rs
index 939e40cf7c4..2efedbb2355 100644
--- a/lightning/src/util/dyn_signer.rs
+++ b/lightning/src/util/dyn_signer.rs
@@ -214,7 +214,7 @@ inner,
 	fn sign_bolt12_invoice(,
 		invoice: &crate::offers::invoice::UnsignedBolt12Invoice
 	) -> Result<secp256k1::schnorr::Signature, ()>,
-	fn get_inbound_payment_key(,) -> ExpandedKey
+	fn get_expanded_key(,) -> ExpandedKey
 );
 
 delegate!(DynKeysInterface, SignerProvider,
@@ -278,7 +278,7 @@ delegate!(DynPhantomKeysInterface, NodeSigner,
 	fn sign_invoice(, invoice: &RawBolt11Invoice, recipient: Recipient) -> Result<RecoverableSignature, ()>,
 	fn sign_bolt12_invoice(, invoice: &crate::offers::invoice::UnsignedBolt12Invoice
 	) -> Result<secp256k1::schnorr::Signature, ()>,
-	fn get_inbound_payment_key(,) -> ExpandedKey
+	fn get_expanded_key(,) -> ExpandedKey
 );
 
 impl SignerProvider for DynPhantomKeysInterface {
diff --git a/lightning/src/util/test_utils.rs b/lightning/src/util/test_utils.rs
index f90bfb97ef7..7945dc587c8 100644
--- a/lightning/src/util/test_utils.rs
+++ b/lightning/src/util/test_utils.rs
@@ -1486,7 +1486,7 @@ impl TestNodeSigner {
 }
 
 impl NodeSigner for TestNodeSigner {
-	fn get_inbound_payment_key(&self) -> ExpandedKey {
+	fn get_expanded_key(&self) -> ExpandedKey {
 		unreachable!()
 	}
 
@@ -1559,8 +1559,8 @@ impl NodeSigner for TestKeysInterface {
 		self.backing.ecdh(recipient, other_key, tweak)
 	}
 
-	fn get_inbound_payment_key(&self) -> ExpandedKey {
-		self.backing.get_inbound_payment_key()
+	fn get_expanded_key(&self) -> ExpandedKey {
+		self.backing.get_expanded_key()
 	}
 
 	fn sign_invoice(