+ /// Signs the [`TaggedHash`] of a BOLT 12 invoice request.
+ ///
+ /// May be called by a function passed to [`UnsignedInvoiceRequest::sign`] where
+ /// `invoice_request` is the callee.
+ ///
+ /// Implementors may check that the `invoice_request` is expected rather than blindly signing
+ /// the tagged hash. An `Ok` result should sign `invoice_request.tagged_hash().as_digest()` with
+ /// the node's signing key or an ephemeral key to preserve privacy, whichever is associated with
+ /// [`UnsignedInvoiceRequest::payer_id`].
+ ///
+ /// [`TaggedHash`]: crate::offers::merkle::TaggedHash
+ fn sign_bolt12_invoice_request(
+ &self, invoice_request: &UnsignedInvoiceRequest
+ ) -> Result<schnorr::Signature, ()>;
+
+ /// Signs the [`TaggedHash`] of a BOLT 12 invoice.
+ ///
+ /// May be called by a function passed to [`UnsignedBolt12Invoice::sign`] where `invoice` is the
+ /// callee.
+ ///
+ /// Implementors may check that the `invoice` is expected rather than blindly signing the tagged
+ /// hash. An `Ok` result should sign `invoice.tagged_hash().as_digest()` with the node's signing
+ /// key or an ephemeral key to preserve privacy, whichever is associated with
+ /// [`UnsignedBolt12Invoice::signing_pubkey`].
+ ///
+ /// [`TaggedHash`]: crate::offers::merkle::TaggedHash
+ fn sign_bolt12_invoice(
+ &self, invoice: &UnsignedBolt12Invoice
+ ) -> Result<schnorr::Signature, ()>;
+