Builder for creating invoice requests

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

diff --git a/lightning/src/offers/merkle.rs b/lightning/src/offers/merkle.rs
index 95183bea20d2a50c29dc62f2890c0e0381cb402d..d34a2a073f345c1b6c375b0775d378b363897eb3 100644 (file)
--- a/lightning/src/offers/merkle.rs
+++ b/lightning/src/offers/merkle.rs
@@ -24,6 +24,35 @@ tlv_stream!(SignatureTlvStream, SignatureTlvStreamRef, SIGNATURE_TYPES, {
        (240, signature: Signature),
 });
 
+/// Error when signing messages.
+#[derive(Debug)]
+pub enum SignError<E> {
+       /// User-defined error when signing the message.
+       Signing(E),
+       /// Error when verifying the produced signature using the given pubkey.
+       Verification(secp256k1::Error),
+}
+
+/// Signs a message digest consisting of a tagged hash of the given bytes, checking if it can be
+/// verified with the supplied pubkey.
+///
+/// Panics if `bytes` is not a well-formed TLV stream containing at least one TLV record.
+pub(super) fn sign_message<F, E>(
+       sign: F, tag: &str, bytes: &[u8], pubkey: PublicKey,
+) -> Result<Signature, SignError<E>>
+where
+       F: FnOnce(&Message) -> Result<Signature, E>
+{
+       let digest = message_digest(tag, bytes);
+       let signature = sign(&digest).map_err(|e| SignError::Signing(e))?;
+
+       let pubkey = pubkey.into();
+       let secp_ctx = Secp256k1::verification_only();
+       secp_ctx.verify_schnorr(&signature, &digest, &pubkey).map_err(|e| SignError::Verification(e))?;
+
+       Ok(signature)
+}
+
 /// Verifies the signature with a pubkey over the given bytes using a tagged hash as the message
 /// digest.
 ///
@@ -31,14 +60,18 @@ tlv_stream!(SignatureTlvStream, SignatureTlvStreamRef, SIGNATURE_TYPES, {
 pub(super) fn verify_signature(
        signature: &Signature, tag: &str, bytes: &[u8], pubkey: PublicKey,
 ) -> Result<(), secp256k1::Error> {
-       let tag = sha256::Hash::hash(tag.as_bytes());
-       let merkle_root = root_hash(bytes);
-       let digest = Message::from_slice(&tagged_hash(tag, merkle_root)).unwrap();
+       let digest = message_digest(tag, bytes);
        let pubkey = pubkey.into();
        let secp_ctx = Secp256k1::verification_only();
        secp_ctx.verify_schnorr(signature, &digest, &pubkey)
 }
 
+fn message_digest(tag: &str, bytes: &[u8]) -> Message {
+       let tag = sha256::Hash::hash(tag.as_bytes());
+       let merkle_root = root_hash(bytes);
+       Message::from_slice(&tagged_hash(tag, merkle_root)).unwrap()
+}
+
 /// Computes a merkle root hash for the given data, which must be a well-formed TLV stream
 /// containing at least one TLV record.
 fn root_hash(data: &[u8]) -> sha256::Hash {