Merge pull request #1908 from jkczyz/2022-11-refund

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

diff --git a/lightning/src/offers/merkle.rs b/lightning/src/offers/merkle.rs
index c7aafb0cfef2516fc8a4cd5965c155652d2594aa..57e7fe6833c2fd7eac8f4ec6125a0e0b2bc58039 100644 (file)
--- a/lightning/src/offers/merkle.rs
+++ b/lightning/src/offers/merkle.rs
@@ -10,6 +10,8 @@
 //! Tagged hashes for use in signature calculation and verification.
 
 use bitcoin::hashes::{Hash, HashEngine, sha256};
+use bitcoin::secp256k1::{Message, PublicKey, Secp256k1, self};
+use bitcoin::secp256k1::schnorr::Signature;
 use crate::io;
 use crate::util::ser::{BigSize, Readable};
 
@@ -18,6 +20,58 @@ use crate::prelude::*;
 /// Valid type range for signature TLV records.
 const SIGNATURE_TYPES: core::ops::RangeInclusive<u64> = 240..=1000;
 
+tlv_stream!(SignatureTlvStream, SignatureTlvStreamRef, SIGNATURE_TYPES, {
+       (240, signature: Signature),
+});
+
+/// Error when signing messages.
+#[derive(Debug, PartialEq)]
+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.
+///
+/// Panics if `bytes` is not a well-formed TLV stream containing at least one TLV record.
+pub(super) fn verify_signature(
+       signature: &Signature, tag: &str, bytes: &[u8], pubkey: PublicKey,
+) -> Result<(), secp256k1::Error> {
+       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 {
@@ -144,6 +198,11 @@ impl<'a> Iterator for TlvStream<'a> {
 #[cfg(test)]
 mod tests {
        use bitcoin::hashes::{Hash, sha256};
+       use bitcoin::secp256k1::{KeyPair, Secp256k1, SecretKey};
+       use core::convert::Infallible;
+       use crate::offers::offer::{Amount, OfferBuilder};
+       use crate::offers::invoice_request::InvoiceRequest;
+       use crate::offers::parse::Bech32Encode;
 
        #[test]
        fn calculates_merkle_root_hash() {
@@ -164,4 +223,50 @@ mod tests {
                        sha256::Hash::from_slice(&hex::decode("ab2e79b1283b0b31e0b035258de23782df6b89a38cfa7237bde69aed1a658c5d").unwrap()).unwrap(),
                );
        }
+
+       #[test]
+       fn calculates_merkle_root_hash_from_invoice_request() {
+               let secp_ctx = Secp256k1::new();
+               let recipient_pubkey = {
+                       let secret_key = SecretKey::from_slice(&hex::decode("4141414141414141414141414141414141414141414141414141414141414141").unwrap()).unwrap();
+                       KeyPair::from_secret_key(&secp_ctx, &secret_key).public_key()
+               };
+               let payer_keys = {
+                       let secret_key = SecretKey::from_slice(&hex::decode("4242424242424242424242424242424242424242424242424242424242424242").unwrap()).unwrap();
+                       KeyPair::from_secret_key(&secp_ctx, &secret_key)
+               };
+
+               // BOLT 12 test vectors
+               let invoice_request = OfferBuilder::new("A Mathematical Treatise".into(), recipient_pubkey)
+                       .amount(Amount::Currency { iso4217_code: *b"USD", amount: 100 })
+                       .build_unchecked()
+                       .request_invoice(vec![0; 8], payer_keys.public_key()).unwrap()
+                       .build_unchecked()
+                       .sign::<_, Infallible>(|digest| Ok(secp_ctx.sign_schnorr_no_aux_rand(digest, &payer_keys)))
+                       .unwrap();
+               assert_eq!(
+                       invoice_request.to_string(),
+                       "lnr1qqyqqqqqqqqqqqqqqcp4256ypqqkgzshgysy6ct5dpjk6ct5d93kzmpq23ex2ct5d9ek293pqthvwfzadd7jejes8q9lhc4rvjxd022zv5l44g6qah82ru5rdpnpjkppqvjx204vgdzgsqpvcp4mldl3plscny0rt707gvpdh6ndydfacz43euzqhrurageg3n7kafgsek6gz3e9w52parv8gs2hlxzk95tzeswywffxlkeyhml0hh46kndmwf4m6xma3tkq2lu04qz3slje2rfthc89vss",
+               );
+               assert_eq!(
+                       super::root_hash(&invoice_request.bytes[..]),
+                       sha256::Hash::from_slice(&hex::decode("608407c18ad9a94d9ea2bcdbe170b6c20c462a7833a197621c916f78cf18e624").unwrap()).unwrap(),
+               );
+       }
+
+       impl AsRef<[u8]> for InvoiceRequest {
+               fn as_ref(&self) -> &[u8] {
+                       &self.bytes
+               }
+       }
+
+       impl Bech32Encode for InvoiceRequest {
+               const BECH32_HRP: &'static str = "lnr";
+       }
+
+       impl core::fmt::Display for InvoiceRequest {
+               fn fmt(&self, f: &mut core::fmt::Formatter) -> Result<(), core::fmt::Error> {
+                       self.fmt_bech32_str(f)
+               }
+       }
 }