Static invoice encoding and parsing
[rust-lightning] / lightning / src / offers / invoice_request.rs
index 02fcd578f949f133e8585ff7bc1b38bc0636f984..cdf94a2e80d5bee168deea35fdb03c817718cdc7 100644 (file)
 //! extern crate bitcoin;
 //! extern crate lightning;
 //!
-//! use bitcoin::network::constants::Network;
-//! use bitcoin::secp256k1::{KeyPair, PublicKey, Secp256k1, SecretKey};
-//! use core::convert::Infallible;
+//! use bitcoin::network::Network;
+//! use bitcoin::secp256k1::{Keypair, PublicKey, Secp256k1, SecretKey};
 //! use lightning::ln::features::OfferFeatures;
+//! use lightning::offers::invoice_request::UnsignedInvoiceRequest;
 //! use lightning::offers::offer::Offer;
 //! use lightning::util::ser::Writeable;
 //!
 //! # fn parse() -> Result<(), lightning::offers::parse::Bolt12ParseError> {
 //! let secp_ctx = Secp256k1::new();
-//! let keys = KeyPair::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32])?);
+//! let keys = Keypair::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32])?);
 //! let pubkey = PublicKey::from(keys);
 //! let mut buffer = Vec::new();
 //!
+//! # use lightning::offers::invoice_request::{ExplicitPayerId, InvoiceRequestBuilder};
+//! # <InvoiceRequestBuilder<ExplicitPayerId, _>>::from(
 //! "lno1qcp4256ypq"
 //!     .parse::<Offer>()?
 //!     .request_invoice(vec![42; 64], pubkey)?
+//! # )
 //!     .chain(Network::Testnet)?
 //!     .amount_msats(1000)?
 //!     .quantity(5)?
 //!     .payer_note("foo".to_string())
 //!     .build()?
-//!     .sign::<_, Infallible>(
-//!         |message| Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &keys))
+//!     .sign(|message: &UnsignedInvoiceRequest|
+//!         Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &keys))
 //!     )
 //!     .expect("failed verifying signature")
 //!     .write(&mut buffer)
 //! ```
 
 use bitcoin::blockdata::constants::ChainHash;
-use bitcoin::network::constants::Network;
-use bitcoin::secp256k1::{KeyPair, PublicKey, Secp256k1, self};
+use bitcoin::network::Network;
+use bitcoin::secp256k1::{Keypair, PublicKey, Secp256k1, self};
 use bitcoin::secp256k1::schnorr::Signature;
-use core::convert::{AsRef, Infallible, TryFrom};
 use core::ops::Deref;
 use crate::sign::EntropySource;
 use crate::io;
 use crate::blinded_path::BlindedPath;
-use crate::ln::PaymentHash;
+use crate::ln::types::PaymentHash;
 use crate::ln::channelmanager::PaymentId;
 use crate::ln::features::InvoiceRequestFeatures;
 use crate::ln::inbound_payment::{ExpandedKey, IV_LEN, Nonce};
 use crate::ln::msgs::DecodeError;
-use crate::offers::invoice::{BlindedPayInfo, DerivedSigningPubkey, ExplicitSigningPubkey, InvoiceBuilder};
-use crate::offers::merkle::{SignError, SignatureTlvStream, SignatureTlvStreamRef, TaggedHash, self};
-use crate::offers::offer::{Offer, OfferContents, OfferTlvStream, OfferTlvStreamRef};
+use crate::offers::invoice::BlindedPayInfo;
+use crate::offers::merkle::{SignError, SignFn, SignatureTlvStream, SignatureTlvStreamRef, TaggedHash, self};
+use crate::offers::offer::{Offer, OfferContents, OfferId, OfferTlvStream, OfferTlvStreamRef};
 use crate::offers::parse::{Bolt12ParseError, ParsedMessage, Bolt12SemanticError};
 use crate::offers::payer::{PayerContents, PayerTlvStream, PayerTlvStreamRef};
 use crate::offers::signer::{Metadata, MetadataMaterial};
-use crate::util::ser::{HighZeroBytesDroppedBigSize, SeekReadable, WithoutLength, Writeable, Writer};
-use crate::util::string::PrintableString;
-
+use crate::util::ser::{HighZeroBytesDroppedBigSize, Readable, SeekReadable, WithoutLength, Writeable, Writer};
+use crate::util::string::{PrintableString, UntrustedString};
+
+#[cfg(not(c_bindings))]
+use {
+       crate::offers::invoice::{DerivedSigningPubkey, ExplicitSigningPubkey, InvoiceBuilder},
+};
+#[cfg(c_bindings)]
+use {
+       crate::offers::invoice::{InvoiceWithDerivedSigningPubkeyBuilder, InvoiceWithExplicitSigningPubkeyBuilder},
+};
+
+#[allow(unused_imports)]
 use crate::prelude::*;
 
 /// Tag for the hash function used when signing an [`InvoiceRequest`]'s merkle root.
@@ -99,6 +111,34 @@ pub struct InvoiceRequestBuilder<'a, 'b, P: PayerIdStrategy, T: secp256k1::Signi
        secp_ctx: Option<&'b Secp256k1<T>>,
 }
 
+/// Builds an [`InvoiceRequest`] from an [`Offer`] for the "offer to be paid" flow.
+///
+/// See [module-level documentation] for usage.
+///
+/// [module-level documentation]: self
+#[cfg(c_bindings)]
+pub struct InvoiceRequestWithExplicitPayerIdBuilder<'a, 'b> {
+       offer: &'a Offer,
+       invoice_request: InvoiceRequestContentsWithoutPayerId,
+       payer_id: Option<PublicKey>,
+       payer_id_strategy: core::marker::PhantomData<ExplicitPayerId>,
+       secp_ctx: Option<&'b Secp256k1<secp256k1::All>>,
+}
+
+/// Builds an [`InvoiceRequest`] from an [`Offer`] for the "offer to be paid" flow.
+///
+/// See [module-level documentation] for usage.
+///
+/// [module-level documentation]: self
+#[cfg(c_bindings)]
+pub struct InvoiceRequestWithDerivedPayerIdBuilder<'a, 'b> {
+       offer: &'a Offer,
+       invoice_request: InvoiceRequestContentsWithoutPayerId,
+       payer_id: Option<PublicKey>,
+       payer_id_strategy: core::marker::PhantomData<DerivedPayerId>,
+       secp_ctx: Option<&'b Secp256k1<secp256k1::All>>,
+}
+
 /// Indicates how [`InvoiceRequest::payer_id`] will be set.
 ///
 /// This is not exported to bindings users as builder patterns don't map outside of move semantics.
@@ -118,6 +158,7 @@ impl PayerIdStrategy for ExplicitPayerId {}
 impl PayerIdStrategy for DerivedPayerId {}
 
 macro_rules! invoice_request_explicit_payer_id_builder_methods { ($self: ident, $self_type: ty) => {
+       #[cfg_attr(c_bindings, allow(dead_code))]
        pub(super) fn new(offer: &'a Offer, metadata: Vec<u8>, payer_id: PublicKey) -> Self {
                Self {
                        offer,
@@ -128,6 +169,7 @@ macro_rules! invoice_request_explicit_payer_id_builder_methods { ($self: ident,
                }
        }
 
+       #[cfg_attr(c_bindings, allow(dead_code))]
        pub(super) fn deriving_metadata<ES: Deref>(
                offer: &'a Offer, payer_id: PublicKey, expanded_key: &ExpandedKey, entropy_source: ES,
                payment_id: PaymentId,
@@ -154,10 +196,13 @@ macro_rules! invoice_request_explicit_payer_id_builder_methods { ($self: ident,
        }
 } }
 
-macro_rules! invoice_request_derived_payer_id_builder_methods { ($self: ident, $self_type: ty) => {
+macro_rules! invoice_request_derived_payer_id_builder_methods { (
+       $self: ident, $self_type: ty, $secp_context: ty
+) => {
+       #[cfg_attr(c_bindings, allow(dead_code))]
        pub(super) fn deriving_payer_id<ES: Deref>(
                offer: &'a Offer, expanded_key: &ExpandedKey, entropy_source: ES,
-               secp_ctx: &'b Secp256k1<T>, payment_id: PaymentId
+               secp_ctx: &'b Secp256k1<$secp_context>, payment_id: PaymentId
        ) -> Self where ES::Target: EntropySource {
                let nonce = Nonce::from_entropy_source(entropy_source);
                let payment_id = Some(payment_id);
@@ -175,13 +220,15 @@ macro_rules! invoice_request_derived_payer_id_builder_methods { ($self: ident, $
        /// Builds a signed [`InvoiceRequest`] after checking for valid semantics.
        pub fn build_and_sign($self: $self_type) -> Result<InvoiceRequest, Bolt12SemanticError> {
                let (unsigned_invoice_request, keys, secp_ctx) = $self.build_with_checks()?;
+               #[cfg(c_bindings)]
+               let mut unsigned_invoice_request = unsigned_invoice_request;
                debug_assert!(keys.is_some());
 
                let secp_ctx = secp_ctx.unwrap();
                let keys = keys.unwrap();
                let invoice_request = unsigned_invoice_request
-                       .sign::<_, Infallible>(
-                               |message| Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &keys))
+                       .sign(|message: &UnsignedInvoiceRequest|
+                               Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &keys))
                        )
                        .unwrap();
                Ok(invoice_request)
@@ -189,8 +236,9 @@ macro_rules! invoice_request_derived_payer_id_builder_methods { ($self: ident, $
 } }
 
 macro_rules! invoice_request_builder_methods { (
-       $self: ident, $self_type: ty, $return_type: ty, $return_value: expr
+       $self: ident, $self_type: ty, $return_type: ty, $return_value: expr, $secp_context: ty $(, $self_mut: tt)?
 ) => {
+       #[cfg_attr(c_bindings, allow(dead_code))]
        fn create_contents(offer: &Offer, metadata: Metadata) -> InvoiceRequestContentsWithoutPayerId {
                let offer = offer.contents.clone();
                InvoiceRequestContentsWithoutPayerId {
@@ -213,7 +261,7 @@ macro_rules! invoice_request_builder_methods { (
        /// offer.
        ///
        /// Successive calls to this method will override the previous setting.
-       pub(crate) fn chain_hash(mut $self: $self_type, chain: ChainHash) -> Result<$return_type, Bolt12SemanticError> {
+       pub(crate) fn chain_hash($($self_mut)* $self: $self_type, chain: ChainHash) -> Result<$return_type, Bolt12SemanticError> {
                if !$self.offer.supports_chain(chain) {
                        return Err(Bolt12SemanticError::UnsupportedChain);
                }
@@ -228,7 +276,7 @@ macro_rules! invoice_request_builder_methods { (
        /// Successive calls to this method will override the previous setting.
        ///
        /// [`quantity`]: Self::quantity
-       pub fn amount_msats(mut $self: $self_type, amount_msats: u64) -> Result<$return_type, Bolt12SemanticError> {
+       pub fn amount_msats($($self_mut)* $self: $self_type, amount_msats: u64) -> Result<$return_type, Bolt12SemanticError> {
                $self.invoice_request.offer.check_amount_msats_for_quantity(
                        Some(amount_msats), $self.invoice_request.quantity
                )?;
@@ -240,7 +288,7 @@ macro_rules! invoice_request_builder_methods { (
        /// does not conform to [`Offer::is_valid_quantity`].
        ///
        /// Successive calls to this method will override the previous setting.
-       pub fn quantity(mut $self: $self_type, quantity: u64) -> Result<$return_type, Bolt12SemanticError> {
+       pub fn quantity($($self_mut)* $self: $self_type, quantity: u64) -> Result<$return_type, Bolt12SemanticError> {
                $self.invoice_request.offer.check_quantity(Some(quantity))?;
                $self.invoice_request.quantity = Some(quantity);
                Ok($return_value)
@@ -249,13 +297,13 @@ macro_rules! invoice_request_builder_methods { (
        /// Sets the [`InvoiceRequest::payer_note`].
        ///
        /// Successive calls to this method will override the previous setting.
-       pub fn payer_note(mut $self: $self_type, payer_note: String) -> $return_type {
+       pub fn payer_note($($self_mut)* $self: $self_type, payer_note: String) -> $return_type {
                $self.invoice_request.payer_note = Some(payer_note);
                $return_value
        }
 
-       fn build_with_checks(mut $self: $self_type) -> Result<
-               (UnsignedInvoiceRequest, Option<KeyPair>, Option<&'b Secp256k1<T>>),
+       fn build_with_checks($($self_mut)* $self: $self_type) -> Result<
+               (UnsignedInvoiceRequest, Option<Keypair>, Option<&'b Secp256k1<$secp_context>>),
                Bolt12SemanticError
        > {
                #[cfg(feature = "std")] {
@@ -285,8 +333,8 @@ macro_rules! invoice_request_builder_methods { (
                Ok($self.build_without_checks())
        }
 
-       fn build_without_checks(mut $self: $self_type) ->
-               (UnsignedInvoiceRequest, Option<KeyPair>, Option<&'b Secp256k1<T>>)
+       fn build_without_checks($($self_mut)* $self: $self_type) ->
+               (UnsignedInvoiceRequest, Option<Keypair>, Option<&'b Secp256k1<$secp_context>>)
        {
                // Create the metadata for stateless verification of a Bolt12Invoice.
                let mut keys = None;
@@ -317,7 +365,10 @@ macro_rules! invoice_request_builder_methods { (
                let payer_id = $self.payer_id.unwrap();
 
                let invoice_request = InvoiceRequestContents {
+                       #[cfg(not(c_bindings))]
                        inner: $self.invoice_request,
+                       #[cfg(c_bindings)]
+                       inner: $self.invoice_request.clone(),
                        payer_id,
                };
                let unsigned_invoice_request = UnsignedInvoiceRequest::new($self.offer, invoice_request);
@@ -328,29 +379,34 @@ macro_rules! invoice_request_builder_methods { (
 
 #[cfg(test)]
 macro_rules! invoice_request_builder_test_methods { (
-       $self: ident, $self_type: ty, $return_type: ty, $return_value: expr
+       $self: ident, $self_type: ty, $return_type: ty, $return_value: expr $(, $self_mut: tt)?
 ) => {
-       fn chain_unchecked(mut $self: $self_type, network: Network) -> $return_type {
+       #[cfg_attr(c_bindings, allow(dead_code))]
+       fn chain_unchecked($($self_mut)* $self: $self_type, network: Network) -> $return_type {
                let chain = ChainHash::using_genesis_block(network);
                $self.invoice_request.chain = Some(chain);
                $return_value
        }
 
-       fn amount_msats_unchecked(mut $self: $self_type, amount_msats: u64) -> $return_type {
+       #[cfg_attr(c_bindings, allow(dead_code))]
+       fn amount_msats_unchecked($($self_mut)* $self: $self_type, amount_msats: u64) -> $return_type {
                $self.invoice_request.amount_msats = Some(amount_msats);
                $return_value
        }
 
-       fn features_unchecked(mut $self: $self_type, features: InvoiceRequestFeatures) -> $return_type {
+       #[cfg_attr(c_bindings, allow(dead_code))]
+       fn features_unchecked($($self_mut)* $self: $self_type, features: InvoiceRequestFeatures) -> $return_type {
                $self.invoice_request.features = features;
                $return_value
        }
 
-       fn quantity_unchecked(mut $self: $self_type, quantity: u64) -> $return_type {
+       #[cfg_attr(c_bindings, allow(dead_code))]
+       fn quantity_unchecked($($self_mut)* $self: $self_type, quantity: u64) -> $return_type {
                $self.invoice_request.quantity = Some(quantity);
                $return_value
        }
 
+       #[cfg_attr(c_bindings, allow(dead_code))]
        pub(super) fn build_unchecked($self: $self_type) -> UnsignedInvoiceRequest {
                $self.build_without_checks().0
        }
@@ -361,14 +417,68 @@ impl<'a, 'b, T: secp256k1::Signing> InvoiceRequestBuilder<'a, 'b, ExplicitPayerI
 }
 
 impl<'a, 'b, T: secp256k1::Signing> InvoiceRequestBuilder<'a, 'b, DerivedPayerId, T> {
-       invoice_request_derived_payer_id_builder_methods!(self, Self);
+       invoice_request_derived_payer_id_builder_methods!(self, Self, T);
 }
 
 impl<'a, 'b, P: PayerIdStrategy, T: secp256k1::Signing> InvoiceRequestBuilder<'a, 'b, P, T> {
-       invoice_request_builder_methods!(self, Self, Self, self);
+       invoice_request_builder_methods!(self, Self, Self, self, T, mut);
 
        #[cfg(test)]
-       invoice_request_builder_test_methods!(self, Self, Self, self);
+       invoice_request_builder_test_methods!(self, Self, Self, self, mut);
+}
+
+#[cfg(all(c_bindings, not(test)))]
+impl<'a, 'b> InvoiceRequestWithExplicitPayerIdBuilder<'a, 'b> {
+       invoice_request_explicit_payer_id_builder_methods!(self, &mut Self);
+       invoice_request_builder_methods!(self, &mut Self, (), (), secp256k1::All);
+}
+
+#[cfg(all(c_bindings, test))]
+impl<'a, 'b> InvoiceRequestWithExplicitPayerIdBuilder<'a, 'b> {
+       invoice_request_explicit_payer_id_builder_methods!(self, &mut Self);
+       invoice_request_builder_methods!(self, &mut Self, &mut Self, self, secp256k1::All);
+       invoice_request_builder_test_methods!(self, &mut Self, &mut Self, self);
+}
+
+#[cfg(all(c_bindings, not(test)))]
+impl<'a, 'b> InvoiceRequestWithDerivedPayerIdBuilder<'a, 'b> {
+       invoice_request_derived_payer_id_builder_methods!(self, &mut Self, secp256k1::All);
+       invoice_request_builder_methods!(self, &mut Self, (), (), secp256k1::All);
+}
+
+#[cfg(all(c_bindings, test))]
+impl<'a, 'b> InvoiceRequestWithDerivedPayerIdBuilder<'a, 'b> {
+       invoice_request_derived_payer_id_builder_methods!(self, &mut Self, secp256k1::All);
+       invoice_request_builder_methods!(self, &mut Self, &mut Self, self, secp256k1::All);
+       invoice_request_builder_test_methods!(self, &mut Self, &mut Self, self);
+}
+
+#[cfg(c_bindings)]
+impl<'a, 'b> From<InvoiceRequestWithExplicitPayerIdBuilder<'a, 'b>>
+for InvoiceRequestBuilder<'a, 'b, ExplicitPayerId, secp256k1::All> {
+       fn from(builder: InvoiceRequestWithExplicitPayerIdBuilder<'a, 'b>) -> Self {
+               let InvoiceRequestWithExplicitPayerIdBuilder {
+                       offer, invoice_request, payer_id, payer_id_strategy, secp_ctx,
+               } = builder;
+
+               Self {
+                       offer, invoice_request, payer_id, payer_id_strategy, secp_ctx,
+               }
+       }
+}
+
+#[cfg(c_bindings)]
+impl<'a, 'b> From<InvoiceRequestWithDerivedPayerIdBuilder<'a, 'b>>
+for InvoiceRequestBuilder<'a, 'b, DerivedPayerId, secp256k1::All> {
+       fn from(builder: InvoiceRequestWithDerivedPayerIdBuilder<'a, 'b>) -> Self {
+               let InvoiceRequestWithDerivedPayerIdBuilder {
+                       offer, invoice_request, payer_id, payer_id_strategy, secp_ctx,
+               } = builder;
+
+               Self {
+                       offer, invoice_request, payer_id, payer_id_strategy, secp_ctx,
+               }
+       }
 }
 
 /// A semantically valid [`InvoiceRequest`] that hasn't been signed.
@@ -377,12 +487,37 @@ impl<'a, 'b, P: PayerIdStrategy, T: secp256k1::Signing> InvoiceRequestBuilder<'a
 ///
 /// This is serialized as a TLV stream, which includes TLV records from the originating message. As
 /// such, it may include unknown, odd TLV records.
+#[derive(Clone)]
 pub struct UnsignedInvoiceRequest {
        bytes: Vec<u8>,
        contents: InvoiceRequestContents,
        tagged_hash: TaggedHash,
 }
 
+/// A function for signing an [`UnsignedInvoiceRequest`].
+pub trait SignInvoiceRequestFn {
+       /// Signs a [`TaggedHash`] computed over the merkle root of `message`'s TLV stream.
+       fn sign_invoice_request(&self, message: &UnsignedInvoiceRequest) -> Result<Signature, ()>;
+}
+
+impl<F> SignInvoiceRequestFn for F
+where
+       F: Fn(&UnsignedInvoiceRequest) -> Result<Signature, ()>,
+{
+       fn sign_invoice_request(&self, message: &UnsignedInvoiceRequest) -> Result<Signature, ()> {
+               self(message)
+       }
+}
+
+impl<F> SignFn<UnsignedInvoiceRequest> for F
+where
+       F: SignInvoiceRequestFn,
+{
+       fn sign(&self, message: &UnsignedInvoiceRequest) -> Result<Signature, ()> {
+               self.sign_invoice_request(message)
+       }
+}
+
 impl UnsignedInvoiceRequest {
        fn new(offer: &Offer, contents: InvoiceRequestContents) -> Self {
                // Use the offer bytes instead of the offer TLV stream as the offer may have contained
@@ -395,7 +530,7 @@ impl UnsignedInvoiceRequest {
                let mut bytes = Vec::new();
                unsigned_tlv_stream.write(&mut bytes).unwrap();
 
-               let tagged_hash = TaggedHash::new(SIGNATURE_TAG, &bytes);
+               let tagged_hash = TaggedHash::from_valid_tlv_stream_bytes(SIGNATURE_TAG, &bytes);
 
                Self { bytes, contents, tagged_hash }
        }
@@ -406,16 +541,15 @@ impl UnsignedInvoiceRequest {
        }
 }
 
-macro_rules! unsigned_invoice_request_sign_method { ($self: ident, $self_type: ty) => {
+macro_rules! unsigned_invoice_request_sign_method { (
+       $self: ident, $self_type: ty $(, $self_mut: tt)?
+) => {
        /// Signs the [`TaggedHash`] of the invoice request using the given function.
        ///
        /// Note: The hash computation may have included unknown, odd TLV records.
-       ///
-       /// This is not exported to bindings users as functions are not yet mapped.
-       pub fn sign<F, E>(mut $self: $self_type, sign: F) -> Result<InvoiceRequest, SignError<E>>
-       where
-               F: FnOnce(&Self) -> Result<Signature, E>
-       {
+       pub fn sign<F: SignInvoiceRequestFn>(
+               $($self_mut)* $self: $self_type, sign: F
+       ) -> Result<InvoiceRequest, SignError> {
                let pubkey = $self.contents.payer_id;
                let signature = merkle::sign_message(sign, &$self, pubkey)?;
 
@@ -426,15 +560,27 @@ macro_rules! unsigned_invoice_request_sign_method { ($self: ident, $self_type: t
                signature_tlv_stream.write(&mut $self.bytes).unwrap();
 
                Ok(InvoiceRequest {
+                       #[cfg(not(c_bindings))]
                        bytes: $self.bytes,
+                       #[cfg(c_bindings)]
+                       bytes: $self.bytes.clone(),
+                       #[cfg(not(c_bindings))]
                        contents: $self.contents,
+                       #[cfg(c_bindings)]
+                       contents: $self.contents.clone(),
                        signature,
                })
        }
 } }
 
+#[cfg(not(c_bindings))]
+impl UnsignedInvoiceRequest {
+       unsigned_invoice_request_sign_method!(self, Self, mut);
+}
+
+#[cfg(c_bindings)]
 impl UnsignedInvoiceRequest {
-       unsigned_invoice_request_sign_method!(self, Self);
+       unsigned_invoice_request_sign_method!(self, &mut Self);
 }
 
 impl AsRef<TaggedHash> for UnsignedInvoiceRequest {
@@ -462,6 +608,9 @@ pub struct InvoiceRequest {
 /// ways to respond depending on whether the signing keys were derived.
 #[derive(Clone, Debug)]
 pub struct VerifiedInvoiceRequest {
+       /// The identifier of the [`Offer`] for which the [`InvoiceRequest`] was made.
+       pub offer_id: OfferId,
+
        /// The verified request.
        inner: InvoiceRequest,
 
@@ -473,7 +622,7 @@ pub struct VerifiedInvoiceRequest {
        /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
        /// [`respond_using_derived_keys`]: Self::respond_using_derived_keys
        /// [`respond_with`]: Self::respond_with
-       pub keys: Option<KeyPair>,
+       pub keys: Option<Keypair>,
 }
 
 /// The contents of an [`InvoiceRequest`], which may be shared with an [`Bolt12Invoice`].
@@ -547,35 +696,25 @@ impl UnsignedInvoiceRequest {
        invoice_request_accessors!(self, self.contents);
 }
 
-impl InvoiceRequest {
-       offer_accessors!(self, self.contents.inner.offer);
-       invoice_request_accessors!(self, self.contents);
-
-       /// Signature of the invoice request using [`payer_id`].
-       ///
-       /// [`payer_id`]: Self::payer_id
-       pub fn signature(&self) -> Signature {
-               self.signature
-       }
-
+macro_rules! invoice_request_respond_with_explicit_signing_pubkey_methods { (
+       $self: ident, $contents: expr, $builder: ty
+) => {
        /// Creates an [`InvoiceBuilder`] for the request with the given required fields and using the
        /// [`Duration`] since [`std::time::SystemTime::UNIX_EPOCH`] as the creation time.
        ///
        /// See [`InvoiceRequest::respond_with_no_std`] for further details where the aforementioned
        /// creation time is used for the `created_at` parameter.
        ///
-       /// This is not exported to bindings users as builder patterns don't map outside of move semantics.
-       ///
        /// [`Duration`]: core::time::Duration
        #[cfg(feature = "std")]
        pub fn respond_with(
-               &self, payment_paths: Vec<(BlindedPayInfo, BlindedPath)>, payment_hash: PaymentHash
-       ) -> Result<InvoiceBuilder<ExplicitSigningPubkey>, Bolt12SemanticError> {
+               &$self, payment_paths: Vec<(BlindedPayInfo, BlindedPath)>, payment_hash: PaymentHash
+       ) -> Result<$builder, Bolt12SemanticError> {
                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_with_no_std(payment_paths, payment_hash, created_at)
+               $contents.respond_with_no_std(payment_paths, payment_hash, created_at)
        }
 
        /// Creates an [`InvoiceBuilder`] for the request with the given required fields.
@@ -599,36 +738,93 @@ impl InvoiceRequest {
        /// If the originating [`Offer`] was created using [`OfferBuilder::deriving_signing_pubkey`],
        /// then use [`InvoiceRequest::verify`] and [`VerifiedInvoiceRequest`] methods instead.
        ///
-       /// This is not exported to bindings users as builder patterns don't map outside of move semantics.
-       ///
        /// [`Bolt12Invoice::created_at`]: crate::offers::invoice::Bolt12Invoice::created_at
        /// [`OfferBuilder::deriving_signing_pubkey`]: crate::offers::offer::OfferBuilder::deriving_signing_pubkey
        pub fn respond_with_no_std(
-               &self, payment_paths: Vec<(BlindedPayInfo, BlindedPath)>, payment_hash: PaymentHash,
+               &$self, payment_paths: Vec<(BlindedPayInfo, BlindedPath)>, payment_hash: PaymentHash,
                created_at: core::time::Duration
-       ) -> Result<InvoiceBuilder<ExplicitSigningPubkey>, Bolt12SemanticError> {
-               if self.invoice_request_features().requires_unknown_bits() {
+       ) -> Result<$builder, Bolt12SemanticError> {
+               if $contents.invoice_request_features().requires_unknown_bits() {
                        return Err(Bolt12SemanticError::UnknownRequiredFeatures);
                }
 
-               InvoiceBuilder::for_offer(self, payment_paths, created_at, payment_hash)
+               let signing_pubkey = match $contents.contents.inner.offer.signing_pubkey() {
+                       Some(signing_pubkey) => signing_pubkey,
+                       None => return Err(Bolt12SemanticError::MissingSigningPubkey),
+               };
+
+               <$builder>::for_offer(&$contents, payment_paths, created_at, payment_hash, signing_pubkey)
        }
 
+       #[cfg(test)]
+       #[allow(dead_code)]
+       pub(super) fn respond_with_no_std_using_signing_pubkey(
+               &$self, payment_paths: Vec<(BlindedPayInfo, BlindedPath)>, payment_hash: PaymentHash,
+               created_at: core::time::Duration, signing_pubkey: PublicKey
+       ) -> Result<$builder, Bolt12SemanticError> {
+               debug_assert!($contents.contents.inner.offer.signing_pubkey().is_none());
+
+               if $contents.invoice_request_features().requires_unknown_bits() {
+                       return Err(Bolt12SemanticError::UnknownRequiredFeatures);
+               }
+
+               <$builder>::for_offer(&$contents, payment_paths, created_at, payment_hash, signing_pubkey)
+       }
+} }
+
+macro_rules! invoice_request_verify_method { ($self: ident, $self_type: ty) => {
        /// Verifies that the request was for an offer created using the given key. Returns the verified
        /// request which contains the derived keys needed to sign a [`Bolt12Invoice`] for the request
        /// if they could be extracted from the metadata.
        ///
        /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
-       pub fn verify<T: secp256k1::Signing>(
-               self, key: &ExpandedKey, secp_ctx: &Secp256k1<T>
+       pub fn verify<
+               #[cfg(not(c_bindings))]
+               T: secp256k1::Signing
+       >(
+               $self: $self_type, key: &ExpandedKey,
+               #[cfg(not(c_bindings))]
+               secp_ctx: &Secp256k1<T>,
+               #[cfg(c_bindings)]
+               secp_ctx: &Secp256k1<secp256k1::All>,
        ) -> Result<VerifiedInvoiceRequest, ()> {
-               let keys = self.contents.inner.offer.verify(&self.bytes, key, secp_ctx)?;
+               let (offer_id, keys) = $self.contents.inner.offer.verify(&$self.bytes, key, secp_ctx)?;
                Ok(VerifiedInvoiceRequest {
-                       inner: self,
+                       offer_id,
+                       #[cfg(not(c_bindings))]
+                       inner: $self,
+                       #[cfg(c_bindings)]
+                       inner: $self.clone(),
                        keys,
                })
        }
 
+} }
+
+#[cfg(not(c_bindings))]
+impl InvoiceRequest {
+       offer_accessors!(self, self.contents.inner.offer);
+       invoice_request_accessors!(self, self.contents);
+       invoice_request_respond_with_explicit_signing_pubkey_methods!(self, self, InvoiceBuilder<ExplicitSigningPubkey>);
+       invoice_request_verify_method!(self, Self);
+}
+
+#[cfg(c_bindings)]
+impl InvoiceRequest {
+       offer_accessors!(self, self.contents.inner.offer);
+       invoice_request_accessors!(self, self.contents);
+       invoice_request_respond_with_explicit_signing_pubkey_methods!(self, self, InvoiceWithExplicitSigningPubkeyBuilder);
+       invoice_request_verify_method!(self, &Self);
+}
+
+impl InvoiceRequest {
+       /// Signature of the invoice request using [`payer_id`].
+       ///
+       /// [`payer_id`]: Self::payer_id
+       pub fn signature(&self) -> Signature {
+               self.signature
+       }
+
        pub(crate) fn as_tlv_stream(&self) -> FullInvoiceRequestTlvStreamRef {
                let (payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream) =
                        self.contents.as_tlv_stream();
@@ -639,55 +835,25 @@ impl InvoiceRequest {
        }
 }
 
-impl VerifiedInvoiceRequest {
-       offer_accessors!(self, self.inner.contents.inner.offer);
-       invoice_request_accessors!(self, self.inner.contents);
-
-       /// Creates an [`InvoiceBuilder`] for the request with the given required fields and using the
-       /// [`Duration`] since [`std::time::SystemTime::UNIX_EPOCH`] as the creation time.
-       ///
-       /// See [`InvoiceRequest::respond_with_no_std`] for further details.
-       ///
-       /// This is not exported to bindings users as builder patterns don't map outside of move semantics.
-       ///
-       /// [`Duration`]: core::time::Duration
-       #[cfg(feature = "std")]
-       pub fn respond_with(
-               &self, payment_paths: Vec<(BlindedPayInfo, BlindedPath)>, payment_hash: PaymentHash
-       ) -> Result<InvoiceBuilder<ExplicitSigningPubkey>, Bolt12SemanticError> {
-               self.inner.respond_with(payment_paths, payment_hash)
-       }
-
-       /// Creates an [`InvoiceBuilder`] for the request with the given required fields.
-       ///
-       /// See [`InvoiceRequest::respond_with_no_std`] for further details.
-       ///
-       /// This is not exported to bindings users as builder patterns don't map outside of move semantics.
-       pub fn respond_with_no_std(
-               &self, payment_paths: Vec<(BlindedPayInfo, BlindedPath)>, payment_hash: PaymentHash,
-               created_at: core::time::Duration
-       ) -> Result<InvoiceBuilder<ExplicitSigningPubkey>, Bolt12SemanticError> {
-               self.inner.respond_with_no_std(payment_paths, payment_hash, created_at)
-       }
-
+macro_rules! invoice_request_respond_with_derived_signing_pubkey_methods { (
+       $self: ident, $contents: expr, $builder: ty
+) => {
        /// Creates an [`InvoiceBuilder`] for the request using the given required fields and that uses
        /// derived signing keys from the originating [`Offer`] to sign the [`Bolt12Invoice`]. Must use
        /// the same [`ExpandedKey`] as the one used to create the offer.
        ///
        /// See [`InvoiceRequest::respond_with`] for further details.
        ///
-       /// This is not exported to bindings users as builder patterns don't map outside of move semantics.
-       ///
        /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
        #[cfg(feature = "std")]
        pub fn respond_using_derived_keys(
-               &self, payment_paths: Vec<(BlindedPayInfo, BlindedPath)>, payment_hash: PaymentHash
-       ) -> Result<InvoiceBuilder<DerivedSigningPubkey>, Bolt12SemanticError> {
+               &$self, payment_paths: Vec<(BlindedPayInfo, BlindedPath)>, payment_hash: PaymentHash
+       ) -> Result<$builder, Bolt12SemanticError> {
                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)
+               $self.respond_using_derived_keys_no_std(payment_paths, payment_hash, created_at)
        }
 
        /// Creates an [`InvoiceBuilder`] for the request using the given required fields and that uses
@@ -696,26 +862,58 @@ impl VerifiedInvoiceRequest {
        ///
        /// See [`InvoiceRequest::respond_with_no_std`] for further details.
        ///
-       /// This is not exported to bindings users as builder patterns don't map outside of move semantics.
-       ///
        /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
        pub fn respond_using_derived_keys_no_std(
-               &self, payment_paths: Vec<(BlindedPayInfo, BlindedPath)>, payment_hash: PaymentHash,
+               &$self, payment_paths: Vec<(BlindedPayInfo, BlindedPath)>, payment_hash: PaymentHash,
                created_at: core::time::Duration
-       ) -> Result<InvoiceBuilder<DerivedSigningPubkey>, Bolt12SemanticError> {
-               if self.inner.invoice_request_features().requires_unknown_bits() {
+       ) -> Result<$builder, Bolt12SemanticError> {
+               if $self.inner.invoice_request_features().requires_unknown_bits() {
                        return Err(Bolt12SemanticError::UnknownRequiredFeatures);
                }
 
-               let keys = match self.keys {
+               let keys = match $self.keys {
                        None => return Err(Bolt12SemanticError::InvalidMetadata),
                        Some(keys) => keys,
                };
 
-               InvoiceBuilder::for_offer_using_keys(
-                       &self.inner, payment_paths, created_at, payment_hash, keys
+               match $contents.contents.inner.offer.signing_pubkey() {
+                       Some(signing_pubkey) => debug_assert_eq!(signing_pubkey, keys.public_key()),
+                       None => return Err(Bolt12SemanticError::MissingSigningPubkey),
+               }
+
+               <$builder>::for_offer_using_keys(
+                       &$self.inner, payment_paths, created_at, payment_hash, keys
                )
        }
+} }
+
+impl VerifiedInvoiceRequest {
+       offer_accessors!(self, self.inner.contents.inner.offer);
+       invoice_request_accessors!(self, self.inner.contents);
+       #[cfg(not(c_bindings))]
+       invoice_request_respond_with_explicit_signing_pubkey_methods!(self, self.inner, InvoiceBuilder<ExplicitSigningPubkey>);
+       #[cfg(c_bindings)]
+       invoice_request_respond_with_explicit_signing_pubkey_methods!(self, self.inner, InvoiceWithExplicitSigningPubkeyBuilder);
+       #[cfg(not(c_bindings))]
+       invoice_request_respond_with_derived_signing_pubkey_methods!(self, self.inner, InvoiceBuilder<DerivedSigningPubkey>);
+       #[cfg(c_bindings)]
+       invoice_request_respond_with_derived_signing_pubkey_methods!(self, self.inner, InvoiceWithDerivedSigningPubkeyBuilder);
+
+       pub(crate) fn fields(&self) -> InvoiceRequestFields {
+               let InvoiceRequestContents {
+                       payer_id,
+                       inner: InvoiceRequestContentsWithoutPayerId {
+                               payer: _, offer: _, chain: _, amount_msats: _, features: _, quantity, payer_note
+                       },
+               } = &self.inner.contents;
+
+               InvoiceRequestFields {
+                       payer_id: *payer_id,
+                       quantity: *quantity,
+                       payer_note_truncated: payer_note.clone()
+                               .map(|mut s| { s.truncate(PAYER_NOTE_LIMIT); UntrustedString(s) }),
+               }
+       }
 }
 
 impl InvoiceRequestContents {
@@ -787,6 +985,7 @@ impl InvoiceRequestContentsWithoutPayerId {
                        quantity: self.quantity,
                        payer_id: None,
                        payer_note: self.payer_note.as_ref(),
+                       paths: None,
                };
 
                (payer, offer, invoice_request)
@@ -819,6 +1018,8 @@ pub(super) const INVOICE_REQUEST_TYPES: core::ops::Range<u64> = 80..160;
 /// [`Refund::payer_id`]: crate::offers::refund::Refund::payer_id
 pub(super) const INVOICE_REQUEST_PAYER_ID_TYPE: u64 = 88;
 
+// This TLV stream is used for both InvoiceRequest and Refund, but not all TLV records are valid for
+// InvoiceRequest as noted below.
 tlv_stream!(InvoiceRequestTlvStream, InvoiceRequestTlvStreamRef, INVOICE_REQUEST_TYPES, {
        (80, chain: ChainHash),
        (82, amount: (u64, HighZeroBytesDroppedBigSize)),
@@ -826,6 +1027,8 @@ tlv_stream!(InvoiceRequestTlvStream, InvoiceRequestTlvStreamRef, INVOICE_REQUEST
        (86, quantity: (u64, HighZeroBytesDroppedBigSize)),
        (INVOICE_REQUEST_PAYER_ID_TYPE, payer_id: PublicKey),
        (89, payer_note: (String, WithoutLength)),
+       // Only used for Refund since the onion message of an InvoiceRequest has a reply path.
+       (90, paths: (Vec<BlindedPath>, WithoutLength)),
 });
 
 type FullInvoiceRequestTlvStream =
@@ -870,7 +1073,7 @@ impl TryFrom<Vec<u8>> for UnsignedInvoiceRequest {
                        (payer_tlv_stream, offer_tlv_stream, invoice_request_tlv_stream)
                )?;
 
-               let tagged_hash = TaggedHash::new(SIGNATURE_TAG, &bytes);
+               let tagged_hash = TaggedHash::from_valid_tlv_stream_bytes(SIGNATURE_TAG, &bytes);
 
                Ok(UnsignedInvoiceRequest { bytes, contents, tagged_hash })
        }
@@ -894,7 +1097,7 @@ impl TryFrom<Vec<u8>> for InvoiceRequest {
                        None => return Err(Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::MissingSignature)),
                        Some(signature) => signature,
                };
-               let message = TaggedHash::new(SIGNATURE_TAG, &bytes);
+               let message = TaggedHash::from_valid_tlv_stream_bytes(SIGNATURE_TAG, &bytes);
                merkle::verify_signature(&signature, &message, contents.payer_id)?;
 
                Ok(InvoiceRequest { bytes, contents, signature })
@@ -908,7 +1111,9 @@ impl TryFrom<PartialInvoiceRequestTlvStream> for InvoiceRequestContents {
                let (
                        PayerTlvStream { metadata },
                        offer_tlv_stream,
-                       InvoiceRequestTlvStream { chain, amount, features, quantity, payer_id, payer_note },
+                       InvoiceRequestTlvStream {
+                               chain, amount, features, quantity, payer_id, payer_note, paths,
+                       },
                ) = tlv_stream;
 
                let payer = match metadata {
@@ -935,6 +1140,10 @@ impl TryFrom<PartialInvoiceRequestTlvStream> for InvoiceRequestContents {
                        Some(payer_id) => payer_id,
                };
 
+               if paths.is_some() {
+                       return Err(Bolt12SemanticError::UnexpectedPaths);
+               }
+
                Ok(InvoiceRequestContents {
                        inner: InvoiceRequestContentsWithoutPayerId {
                                payer, offer, chain, amount_msats: amount, features, quantity, payer_note,
@@ -944,14 +1153,59 @@ impl TryFrom<PartialInvoiceRequestTlvStream> for InvoiceRequestContents {
        }
 }
 
+/// Fields sent in an [`InvoiceRequest`] message to include in [`PaymentContext::Bolt12Offer`].
+///
+/// [`PaymentContext::Bolt12Offer`]: crate::blinded_path::payment::PaymentContext::Bolt12Offer
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct InvoiceRequestFields {
+       /// A possibly transient pubkey used to sign the invoice request.
+       pub payer_id: PublicKey,
+
+       /// The quantity of the offer's item conforming to [`Offer::is_valid_quantity`].
+       pub quantity: Option<u64>,
+
+       /// A payer-provided note which will be seen by the recipient and reflected back in the invoice
+       /// response. Truncated to [`PAYER_NOTE_LIMIT`] characters.
+       pub payer_note_truncated: Option<UntrustedString>,
+}
+
+/// The maximum number of characters included in [`InvoiceRequestFields::payer_note_truncated`].
+pub const PAYER_NOTE_LIMIT: usize = 512;
+
+impl Writeable for InvoiceRequestFields {
+       fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
+               write_tlv_fields!(writer, {
+                       (0, self.payer_id, required),
+                       (2, self.quantity.map(|v| HighZeroBytesDroppedBigSize(v)), option),
+                       (4, self.payer_note_truncated.as_ref().map(|s| WithoutLength(&s.0)), option),
+               });
+               Ok(())
+       }
+}
+
+impl Readable for InvoiceRequestFields {
+       fn read<R: io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
+               _init_and_read_len_prefixed_tlv_fields!(reader, {
+                       (0, payer_id, required),
+                       (2, quantity, (option, encoding: (u64, HighZeroBytesDroppedBigSize))),
+                       (4, payer_note_truncated, (option, encoding: (String, WithoutLength))),
+               });
+
+               Ok(InvoiceRequestFields {
+                       payer_id: payer_id.0.unwrap(),
+                       quantity,
+                       payer_note_truncated: payer_note_truncated.map(|s| UntrustedString(s)),
+               })
+       }
+}
+
 #[cfg(test)]
 mod tests {
-       use super::{InvoiceRequest, InvoiceRequestTlvStreamRef, SIGNATURE_TAG, UnsignedInvoiceRequest};
+       use super::{InvoiceRequest, InvoiceRequestFields, InvoiceRequestTlvStreamRef, PAYER_NOTE_LIMIT, SIGNATURE_TAG, UnsignedInvoiceRequest};
 
        use bitcoin::blockdata::constants::ChainHash;
-       use bitcoin::network::constants::Network;
-       use bitcoin::secp256k1::{KeyPair, Secp256k1, SecretKey, self};
-       use core::convert::{Infallible, TryFrom};
+       use bitcoin::network::Network;
+       use bitcoin::secp256k1::{Keypair, Secp256k1, SecretKey, self};
        use core::num::NonZeroU64;
        #[cfg(feature = "std")]
        use core::time::Duration;
@@ -974,16 +1228,18 @@ mod tests {
        use crate::offers::parse::{Bolt12ParseError, Bolt12SemanticError};
        use crate::offers::payer::PayerTlvStreamRef;
        use crate::offers::test_utils::*;
-       use crate::util::ser::{BigSize, Writeable};
-       use crate::util::string::PrintableString;
+       use crate::util::ser::{BigSize, Readable, Writeable};
+       use crate::util::string::{PrintableString, UntrustedString};
 
        #[test]
        fn builds_invoice_request_with_defaults() {
-               let unsigned_invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let unsigned_invoice_request = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
                        .build().unwrap();
+               #[cfg(c_bindings)]
+               let mut unsigned_invoice_request = unsigned_invoice_request;
 
                let mut buffer = Vec::new();
                unsigned_invoice_request.write(&mut buffer).unwrap();
@@ -992,14 +1248,14 @@ mod tests {
                assert_eq!(unsigned_invoice_request.payer_metadata(), &[1; 32]);
                assert_eq!(unsigned_invoice_request.chains(), vec![ChainHash::using_genesis_block(Network::Bitcoin)]);
                assert_eq!(unsigned_invoice_request.metadata(), None);
-               assert_eq!(unsigned_invoice_request.amount(), Some(&Amount::Bitcoin { amount_msats: 1000 }));
-               assert_eq!(unsigned_invoice_request.description(), PrintableString("foo"));
+               assert_eq!(unsigned_invoice_request.amount(), Some(Amount::Bitcoin { amount_msats: 1000 }));
+               assert_eq!(unsigned_invoice_request.description(), Some(PrintableString("")));
                assert_eq!(unsigned_invoice_request.offer_features(), &OfferFeatures::empty());
                assert_eq!(unsigned_invoice_request.absolute_expiry(), None);
                assert_eq!(unsigned_invoice_request.paths(), &[]);
                assert_eq!(unsigned_invoice_request.issuer(), None);
                assert_eq!(unsigned_invoice_request.supported_quantity(), Quantity::One);
-               assert_eq!(unsigned_invoice_request.signing_pubkey(), recipient_pubkey());
+               assert_eq!(unsigned_invoice_request.signing_pubkey(), Some(recipient_pubkey()));
                assert_eq!(unsigned_invoice_request.chain(), ChainHash::using_genesis_block(Network::Bitcoin));
                assert_eq!(unsigned_invoice_request.amount_msats(), None);
                assert_eq!(unsigned_invoice_request.invoice_request_features(), &InvoiceRequestFeatures::empty());
@@ -1024,14 +1280,14 @@ mod tests {
                assert_eq!(invoice_request.payer_metadata(), &[1; 32]);
                assert_eq!(invoice_request.chains(), vec![ChainHash::using_genesis_block(Network::Bitcoin)]);
                assert_eq!(invoice_request.metadata(), None);
-               assert_eq!(invoice_request.amount(), Some(&Amount::Bitcoin { amount_msats: 1000 }));
-               assert_eq!(invoice_request.description(), PrintableString("foo"));
+               assert_eq!(invoice_request.amount(), Some(Amount::Bitcoin { amount_msats: 1000 }));
+               assert_eq!(invoice_request.description(), Some(PrintableString("")));
                assert_eq!(invoice_request.offer_features(), &OfferFeatures::empty());
                assert_eq!(invoice_request.absolute_expiry(), None);
                assert_eq!(invoice_request.paths(), &[]);
                assert_eq!(invoice_request.issuer(), None);
                assert_eq!(invoice_request.supported_quantity(), Quantity::One);
-               assert_eq!(invoice_request.signing_pubkey(), recipient_pubkey());
+               assert_eq!(invoice_request.signing_pubkey(), Some(recipient_pubkey()));
                assert_eq!(invoice_request.chain(), ChainHash::using_genesis_block(Network::Bitcoin));
                assert_eq!(invoice_request.amount_msats(), None);
                assert_eq!(invoice_request.invoice_request_features(), &InvoiceRequestFeatures::empty());
@@ -1039,7 +1295,7 @@ mod tests {
                assert_eq!(invoice_request.payer_id(), payer_pubkey());
                assert_eq!(invoice_request.payer_note(), None);
 
-               let message = TaggedHash::new(SIGNATURE_TAG, &invoice_request.bytes);
+               let message = TaggedHash::from_valid_tlv_stream_bytes(SIGNATURE_TAG, &invoice_request.bytes);
                assert!(merkle::verify_signature(&invoice_request.signature, &message, payer_pubkey()).is_ok());
 
                assert_eq!(
@@ -1051,7 +1307,7 @@ mod tests {
                                        metadata: None,
                                        currency: None,
                                        amount: Some(1000),
-                                       description: Some(&String::from("foo")),
+                                       description: Some(&String::from("")),
                                        features: None,
                                        absolute_expiry: None,
                                        paths: None,
@@ -1066,6 +1322,7 @@ mod tests {
                                        quantity: None,
                                        payer_id: Some(&payer_pubkey()),
                                        payer_note: None,
+                                       paths: None,
                                },
                                SignatureTlvStreamRef { signature: Some(&invoice_request.signature()) },
                        ),
@@ -1082,7 +1339,7 @@ mod tests {
                let future_expiry = Duration::from_secs(u64::max_value());
                let past_expiry = Duration::from_secs(0);
 
-               if let Err(e) = OfferBuilder::new("foo".into(), recipient_pubkey())
+               if let Err(e) = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .absolute_expiry(future_expiry)
                        .build().unwrap()
@@ -1092,7 +1349,7 @@ mod tests {
                        panic!("error building invoice_request: {:?}", e);
                }
 
-               match OfferBuilder::new("foo".into(), recipient_pubkey())
+               match OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .absolute_expiry(past_expiry)
                        .build().unwrap()
@@ -1112,7 +1369,7 @@ mod tests {
                let secp_ctx = Secp256k1::new();
                let payment_id = PaymentId([1; 32]);
 
-               let offer = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let offer = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap();
                let invoice_request = offer
@@ -1144,7 +1401,7 @@ mod tests {
                let mut bytes = Vec::new();
                tlv_stream.write(&mut bytes).unwrap();
 
-               let message = TaggedHash::new(INVOICE_SIGNATURE_TAG, &bytes);
+               let message = TaggedHash::from_valid_tlv_stream_bytes(INVOICE_SIGNATURE_TAG, &bytes);
                let signature = merkle::sign_message(recipient_sign, &message, recipient_pubkey()).unwrap();
                signature_tlv_stream.signature = Some(&signature);
 
@@ -1167,7 +1424,7 @@ mod tests {
                let mut bytes = Vec::new();
                tlv_stream.write(&mut bytes).unwrap();
 
-               let message = TaggedHash::new(INVOICE_SIGNATURE_TAG, &bytes);
+               let message = TaggedHash::from_valid_tlv_stream_bytes(INVOICE_SIGNATURE_TAG, &bytes);
                let signature = merkle::sign_message(recipient_sign, &message, recipient_pubkey()).unwrap();
                signature_tlv_stream.signature = Some(&signature);
 
@@ -1185,7 +1442,7 @@ mod tests {
                let secp_ctx = Secp256k1::new();
                let payment_id = PaymentId([1; 32]);
 
-               let offer = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let offer = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap();
                let invoice_request = offer
@@ -1216,7 +1473,7 @@ mod tests {
                let mut bytes = Vec::new();
                tlv_stream.write(&mut bytes).unwrap();
 
-               let message = TaggedHash::new(INVOICE_SIGNATURE_TAG, &bytes);
+               let message = TaggedHash::from_valid_tlv_stream_bytes(INVOICE_SIGNATURE_TAG, &bytes);
                let signature = merkle::sign_message(recipient_sign, &message, recipient_pubkey()).unwrap();
                signature_tlv_stream.signature = Some(&signature);
 
@@ -1239,7 +1496,7 @@ mod tests {
                let mut bytes = Vec::new();
                tlv_stream.write(&mut bytes).unwrap();
 
-               let message = TaggedHash::new(INVOICE_SIGNATURE_TAG, &bytes);
+               let message = TaggedHash::from_valid_tlv_stream_bytes(INVOICE_SIGNATURE_TAG, &bytes);
                let signature = merkle::sign_message(recipient_sign, &message, recipient_pubkey()).unwrap();
                signature_tlv_stream.signature = Some(&signature);
 
@@ -1255,7 +1512,7 @@ mod tests {
                let mainnet = ChainHash::using_genesis_block(Network::Bitcoin);
                let testnet = ChainHash::using_genesis_block(Network::Testnet);
 
-               let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let invoice_request = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1266,7 +1523,7 @@ mod tests {
                assert_eq!(invoice_request.chain(), mainnet);
                assert_eq!(tlv_stream.chain, None);
 
-               let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let invoice_request = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .chain(Network::Testnet)
                        .build().unwrap()
@@ -1278,7 +1535,7 @@ mod tests {
                assert_eq!(invoice_request.chain(), testnet);
                assert_eq!(tlv_stream.chain, Some(&testnet));
 
-               let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let invoice_request = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .chain(Network::Bitcoin)
                        .chain(Network::Testnet)
@@ -1291,7 +1548,7 @@ mod tests {
                assert_eq!(invoice_request.chain(), mainnet);
                assert_eq!(tlv_stream.chain, None);
 
-               let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let invoice_request = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .chain(Network::Bitcoin)
                        .chain(Network::Testnet)
@@ -1305,7 +1562,7 @@ mod tests {
                assert_eq!(invoice_request.chain(), testnet);
                assert_eq!(tlv_stream.chain, Some(&testnet));
 
-               match OfferBuilder::new("foo".into(), recipient_pubkey())
+               match OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .chain(Network::Testnet)
                        .build().unwrap()
@@ -1316,7 +1573,7 @@ mod tests {
                        Err(e) => assert_eq!(e, Bolt12SemanticError::UnsupportedChain),
                }
 
-               match OfferBuilder::new("foo".into(), recipient_pubkey())
+               match OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .chain(Network::Testnet)
                        .build().unwrap()
@@ -1330,7 +1587,7 @@ mod tests {
 
        #[test]
        fn builds_invoice_request_with_amount() {
-               let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let invoice_request = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1341,7 +1598,7 @@ mod tests {
                assert_eq!(invoice_request.amount_msats(), Some(1000));
                assert_eq!(tlv_stream.amount, Some(1000));
 
-               let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let invoice_request = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1353,7 +1610,7 @@ mod tests {
                assert_eq!(invoice_request.amount_msats(), Some(1000));
                assert_eq!(tlv_stream.amount, Some(1000));
 
-               let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let invoice_request = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1364,7 +1621,7 @@ mod tests {
                assert_eq!(invoice_request.amount_msats(), Some(1001));
                assert_eq!(tlv_stream.amount, Some(1001));
 
-               match OfferBuilder::new("foo".into(), recipient_pubkey())
+               match OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1374,7 +1631,7 @@ mod tests {
                        Err(e) => assert_eq!(e, Bolt12SemanticError::InsufficientAmount),
                }
 
-               match OfferBuilder::new("foo".into(), recipient_pubkey())
+               match OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .supported_quantity(Quantity::Unbounded)
                        .build().unwrap()
@@ -1386,7 +1643,7 @@ mod tests {
                        Err(e) => assert_eq!(e, Bolt12SemanticError::InsufficientAmount),
                }
 
-               match OfferBuilder::new("foo".into(), recipient_pubkey())
+               match OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1396,7 +1653,7 @@ mod tests {
                        Err(e) => assert_eq!(e, Bolt12SemanticError::InvalidAmount),
                }
 
-               match OfferBuilder::new("foo".into(), recipient_pubkey())
+               match OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .supported_quantity(Quantity::Unbounded)
                        .build().unwrap()
@@ -1409,7 +1666,7 @@ mod tests {
                        Err(e) => assert_eq!(e, Bolt12SemanticError::InsufficientAmount),
                }
 
-               match OfferBuilder::new("foo".into(), recipient_pubkey())
+               match OfferBuilder::new(recipient_pubkey())
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
                        .build()
@@ -1418,7 +1675,7 @@ mod tests {
                        Err(e) => assert_eq!(e, Bolt12SemanticError::MissingAmount),
                }
 
-               match OfferBuilder::new("foo".into(), recipient_pubkey())
+               match OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .supported_quantity(Quantity::Unbounded)
                        .build().unwrap()
@@ -1433,7 +1690,7 @@ mod tests {
 
        #[test]
        fn builds_invoice_request_with_features() {
-               let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let invoice_request = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1444,7 +1701,7 @@ mod tests {
                assert_eq!(invoice_request.invoice_request_features(), &InvoiceRequestFeatures::unknown());
                assert_eq!(tlv_stream.features, Some(&InvoiceRequestFeatures::unknown()));
 
-               let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let invoice_request = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1462,7 +1719,7 @@ mod tests {
                let one = NonZeroU64::new(1).unwrap();
                let ten = NonZeroU64::new(10).unwrap();
 
-               let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let invoice_request = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .supported_quantity(Quantity::One)
                        .build().unwrap()
@@ -1473,7 +1730,7 @@ mod tests {
                assert_eq!(invoice_request.quantity(), None);
                assert_eq!(tlv_stream.quantity, None);
 
-               match OfferBuilder::new("foo".into(), recipient_pubkey())
+               match OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .supported_quantity(Quantity::One)
                        .build().unwrap()
@@ -1485,7 +1742,7 @@ mod tests {
                        Err(e) => assert_eq!(e, Bolt12SemanticError::UnexpectedQuantity),
                }
 
-               let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let invoice_request = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .supported_quantity(Quantity::Bounded(ten))
                        .build().unwrap()
@@ -1498,7 +1755,7 @@ mod tests {
                assert_eq!(invoice_request.amount_msats(), Some(10_000));
                assert_eq!(tlv_stream.amount, Some(10_000));
 
-               match OfferBuilder::new("foo".into(), recipient_pubkey())
+               match OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .supported_quantity(Quantity::Bounded(ten))
                        .build().unwrap()
@@ -1510,7 +1767,7 @@ mod tests {
                        Err(e) => assert_eq!(e, Bolt12SemanticError::InvalidQuantity),
                }
 
-               let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let invoice_request = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .supported_quantity(Quantity::Unbounded)
                        .build().unwrap()
@@ -1523,7 +1780,7 @@ mod tests {
                assert_eq!(invoice_request.amount_msats(), Some(2_000));
                assert_eq!(tlv_stream.amount, Some(2_000));
 
-               match OfferBuilder::new("foo".into(), recipient_pubkey())
+               match OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .supported_quantity(Quantity::Unbounded)
                        .build().unwrap()
@@ -1534,7 +1791,7 @@ mod tests {
                        Err(e) => assert_eq!(e, Bolt12SemanticError::MissingQuantity),
                }
 
-               match OfferBuilder::new("foo".into(), recipient_pubkey())
+               match OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .supported_quantity(Quantity::Bounded(one))
                        .build().unwrap()
@@ -1548,7 +1805,7 @@ mod tests {
 
        #[test]
        fn builds_invoice_request_with_payer_note() {
-               let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let invoice_request = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1559,7 +1816,7 @@ mod tests {
                assert_eq!(invoice_request.payer_note(), Some(PrintableString("bar")));
                assert_eq!(tlv_stream.payer_note, Some(&String::from("bar")));
 
-               let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let invoice_request = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1574,18 +1831,18 @@ mod tests {
 
        #[test]
        fn fails_signing_invoice_request() {
-               match OfferBuilder::new("foo".into(), recipient_pubkey())
+               match OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
                        .build().unwrap()
-                       .sign(|_| Err(()))
+                       .sign(fail_sign)
                {
                        Ok(_) => panic!("expected error"),
-                       Err(e) => assert_eq!(e, SignError::Signing(())),
+                       Err(e) => assert_eq!(e, SignError::Signing),
                }
 
-               match OfferBuilder::new("foo".into(), recipient_pubkey())
+               match OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1599,7 +1856,7 @@ mod tests {
 
        #[test]
        fn fails_responding_with_unknown_required_features() {
-               match OfferBuilder::new("foo".into(), recipient_pubkey())
+               match OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![42; 32], payer_pubkey()).unwrap()
@@ -1615,7 +1872,7 @@ mod tests {
 
        #[test]
        fn parses_invoice_request_with_metadata() {
-               let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let invoice_request = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1632,7 +1889,7 @@ mod tests {
 
        #[test]
        fn parses_invoice_request_with_chain() {
-               let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let invoice_request = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1647,7 +1904,7 @@ mod tests {
                        panic!("error parsing invoice_request: {:?}", e);
                }
 
-               let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let invoice_request = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1666,7 +1923,7 @@ mod tests {
 
        #[test]
        fn parses_invoice_request_with_amount() {
-               let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let invoice_request = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1680,7 +1937,7 @@ mod tests {
                        panic!("error parsing invoice_request: {:?}", e);
                }
 
-               let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let invoice_request = OfferBuilder::new(recipient_pubkey())
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
                        .amount_msats(1000).unwrap()
@@ -1694,7 +1951,7 @@ mod tests {
                        panic!("error parsing invoice_request: {:?}", e);
                }
 
-               let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let invoice_request = OfferBuilder::new(recipient_pubkey())
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
                        .build_unchecked()
@@ -1708,7 +1965,7 @@ mod tests {
                        Err(e) => assert_eq!(e, Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::MissingAmount)),
                }
 
-               let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let invoice_request = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1724,7 +1981,8 @@ mod tests {
                        Err(e) => assert_eq!(e, Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::InsufficientAmount)),
                }
 
-               let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let invoice_request = OfferBuilder::new(recipient_pubkey())
+                       .description("foo".to_string())
                        .amount(Amount::Currency { iso4217_code: *b"USD", amount: 1000 })
                        .build_unchecked()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1741,7 +1999,7 @@ mod tests {
                        },
                }
 
-               let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let invoice_request = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .supported_quantity(Quantity::Unbounded)
                        .build().unwrap()
@@ -1764,7 +2022,7 @@ mod tests {
                let one = NonZeroU64::new(1).unwrap();
                let ten = NonZeroU64::new(10).unwrap();
 
-               let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let invoice_request = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .supported_quantity(Quantity::One)
                        .build().unwrap()
@@ -1779,7 +2037,7 @@ mod tests {
                        panic!("error parsing invoice_request: {:?}", e);
                }
 
-               let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let invoice_request = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .supported_quantity(Quantity::One)
                        .build().unwrap()
@@ -1799,7 +2057,7 @@ mod tests {
                        },
                }
 
-               let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let invoice_request = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .supported_quantity(Quantity::Bounded(ten))
                        .build().unwrap()
@@ -1816,7 +2074,7 @@ mod tests {
                        panic!("error parsing invoice_request: {:?}", e);
                }
 
-               let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let invoice_request = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .supported_quantity(Quantity::Bounded(ten))
                        .build().unwrap()
@@ -1834,7 +2092,7 @@ mod tests {
                        Err(e) => assert_eq!(e, Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::InvalidQuantity)),
                }
 
-               let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let invoice_request = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .supported_quantity(Quantity::Unbounded)
                        .build().unwrap()
@@ -1851,7 +2109,7 @@ mod tests {
                        panic!("error parsing invoice_request: {:?}", e);
                }
 
-               let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let invoice_request = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .supported_quantity(Quantity::Unbounded)
                        .build().unwrap()
@@ -1867,7 +2125,7 @@ mod tests {
                        Err(e) => assert_eq!(e, Bolt12ParseError::InvalidSemantics(Bolt12SemanticError::MissingQuantity)),
                }
 
-               let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let invoice_request = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .supported_quantity(Quantity::Bounded(one))
                        .build().unwrap()
@@ -1886,7 +2144,7 @@ mod tests {
 
        #[test]
        fn fails_parsing_invoice_request_without_metadata() {
-               let offer = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let offer = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap();
                let unsigned_invoice_request = offer.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1907,7 +2165,7 @@ mod tests {
 
        #[test]
        fn fails_parsing_invoice_request_without_payer_id() {
-               let offer = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let offer = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap();
                let unsigned_invoice_request = offer.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1926,7 +2184,7 @@ mod tests {
 
        #[test]
        fn fails_parsing_invoice_request_without_node_id() {
-               let offer = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let offer = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap();
                let unsigned_invoice_request = offer.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1948,7 +2206,7 @@ mod tests {
        #[test]
        fn fails_parsing_invoice_request_without_signature() {
                let mut buffer = Vec::new();
-               OfferBuilder::new("foo".into(), recipient_pubkey())
+               OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1964,7 +2222,7 @@ mod tests {
 
        #[test]
        fn fails_parsing_invoice_request_with_invalid_signature() {
-               let mut invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey())
+               let mut invoice_request = OfferBuilder::new(recipient_pubkey())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], payer_pubkey()).unwrap()
@@ -1987,14 +2245,14 @@ mod tests {
        #[test]
        fn fails_parsing_invoice_request_with_extra_tlv_records() {
                let secp_ctx = Secp256k1::new();
-               let keys = KeyPair::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap());
-               let invoice_request = OfferBuilder::new("foo".into(), keys.public_key())
+               let keys = Keypair::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap());
+               let invoice_request = OfferBuilder::new(keys.public_key())
                        .amount_msats(1000)
                        .build().unwrap()
                        .request_invoice(vec![1; 32], keys.public_key()).unwrap()
                        .build().unwrap()
-                       .sign::<_, Infallible>(
-                               |message| Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &keys))
+                       .sign(|message: &UnsignedInvoiceRequest|
+                               Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &keys))
                        )
                        .unwrap();
 
@@ -2009,4 +2267,51 @@ mod tests {
                        Err(e) => assert_eq!(e, Bolt12ParseError::Decode(DecodeError::InvalidValue)),
                }
        }
+
+       #[test]
+       fn copies_verified_invoice_request_fields() {
+               let node_id = recipient_pubkey();
+               let expanded_key = ExpandedKey::new(&KeyMaterial([42; 32]));
+               let entropy = FixedEntropy {};
+               let secp_ctx = Secp256k1::new();
+
+               #[cfg(c_bindings)]
+               use crate::offers::offer::OfferWithDerivedMetadataBuilder as OfferBuilder;
+               let offer = OfferBuilder
+                       ::deriving_signing_pubkey(node_id, &expanded_key, &entropy, &secp_ctx)
+                       .chain(Network::Testnet)
+                       .amount_msats(1000)
+                       .supported_quantity(Quantity::Unbounded)
+                       .build().unwrap();
+               assert_eq!(offer.signing_pubkey(), Some(node_id));
+
+               let invoice_request = offer.request_invoice(vec![1; 32], payer_pubkey()).unwrap()
+                       .chain(Network::Testnet).unwrap()
+                       .quantity(1).unwrap()
+                       .payer_note("0".repeat(PAYER_NOTE_LIMIT * 2))
+                       .build().unwrap()
+                       .sign(payer_sign).unwrap();
+               match invoice_request.verify(&expanded_key, &secp_ctx) {
+                       Ok(invoice_request) => {
+                               let fields = invoice_request.fields();
+                               assert_eq!(invoice_request.offer_id, offer.id());
+                               assert_eq!(
+                                       fields,
+                                       InvoiceRequestFields {
+                                               payer_id: payer_pubkey(),
+                                               quantity: Some(1),
+                                               payer_note_truncated: Some(UntrustedString("0".repeat(PAYER_NOTE_LIMIT))),
+                                       }
+                               );
+
+                               let mut buffer = Vec::new();
+                               fields.write(&mut buffer).unwrap();
+
+                               let deserialized_fields: InvoiceRequestFields =
+                                       Readable::read(&mut buffer.as_slice()).unwrap();
+                               assert_eq!(deserialized_fields, fields);
+                       },
+                       Err(_) => panic!("unexpected error"),
+               }
+       }
 }