X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Foffers%2Fmerkle.rs;h=7390b58fef8ef780a68f58aa50438dcbe1979d71;hb=b3e7aac4a708ab7c41b7ece7839fd18fe66c1e0a;hp=57e7fe6833c2fd7eac8f4ec6125a0e0b2bc58039;hpb=4a0010d7393bb32305bdb3d859735b7b563462eb;p=rust-lightning diff --git a/lightning/src/offers/merkle.rs b/lightning/src/offers/merkle.rs index 57e7fe68..7390b58f 100644 --- a/lightning/src/offers/merkle.rs +++ b/lightning/src/offers/merkle.rs @@ -12,8 +12,9 @@ use bitcoin::hashes::{Hash, HashEngine, sha256}; use bitcoin::secp256k1::{Message, PublicKey, Secp256k1, self}; use bitcoin::secp256k1::schnorr::Signature; +use core::convert::AsRef; use crate::io; -use crate::util::ser::{BigSize, Readable}; +use crate::util::ser::{BigSize, Readable, Writeable, Writer}; use crate::prelude::*; @@ -24,6 +25,34 @@ tlv_stream!(SignatureTlvStream, SignatureTlvStreamRef, SIGNATURE_TYPES, { (240, signature: Signature), }); +/// A hash for use in a specific context by tweaking with a context-dependent tag as per [BIP 340] +/// and computed over the merkle root of a TLV stream to sign as defined in [BOLT 12]. +/// +/// [BIP 340]: https://github.com/bitcoin/bips/blob/master/bip-0340.mediawiki +/// [BOLT 12]: https://github.com/rustyrussell/lightning-rfc/blob/guilt/offers/12-offer-encoding.md#signature-calculation +#[derive(Debug, PartialEq)] +pub struct TaggedHash(Message); + +impl TaggedHash { + /// Creates a tagged hash with the given parameters. + /// + /// Panics if `tlv_stream` is not a well-formed TLV stream containing at least one TLV record. + pub(super) fn new(tag: &str, tlv_stream: &[u8]) -> Self { + Self(message_digest(tag, tlv_stream)) + } + + /// Returns the digest to sign. + pub fn as_digest(&self) -> &Message { + &self.0 + } +} + +impl AsRef for TaggedHash { + fn as_ref(&self) -> &TaggedHash { + self + } +} + /// Error when signing messages. #[derive(Debug, PartialEq)] pub enum SignError { @@ -33,40 +62,44 @@ pub enum SignError { 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. +/// Signs a [`TaggedHash`] computed over the merkle root of `message`'s TLV stream, 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( - sign: F, tag: &str, bytes: &[u8], pubkey: PublicKey, +/// Since `message` is any type that implements [`AsRef`], `sign` may be a closure that +/// takes a message such as [`Bolt12Invoice`] or [`InvoiceRequest`]. This allows further message +/// verification before signing its [`TaggedHash`]. +/// +/// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice +/// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest +pub(super) fn sign_message( + sign: F, message: &T, pubkey: PublicKey, ) -> Result> where - F: FnOnce(&Message) -> Result + F: FnOnce(&T) -> Result, + T: AsRef, { - let digest = message_digest(tag, bytes); - let signature = sign(&digest).map_err(|e| SignError::Signing(e))?; + let signature = sign(message).map_err(|e| SignError::Signing(e))?; + let digest = message.as_ref().as_digest(); let pubkey = pubkey.into(); let secp_ctx = Secp256k1::verification_only(); - secp_ctx.verify_schnorr(&signature, &digest, &pubkey).map_err(|e| SignError::Verification(e))?; + 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 +/// Verifies the signature with a pubkey over the given message 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, + signature: &Signature, message: TaggedHash, pubkey: PublicKey, ) -> Result<(), secp256k1::Error> { - let digest = message_digest(tag, bytes); + let digest = message.as_digest(); let pubkey = pubkey.into(); let secp_ctx = Secp256k1::verification_only(); - secp_ctx.verify_schnorr(signature, &digest, &pubkey) + secp_ctx.verify_schnorr(signature, digest, &pubkey) } -fn message_digest(tag: &str, bytes: &[u8]) -> Message { +pub(super) 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() @@ -75,22 +108,21 @@ fn message_digest(tag: &str, bytes: &[u8]) -> Message { /// 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 { - let mut tlv_stream = TlvStream::new(&data[..]).peekable(); let nonce_tag = tagged_hash_engine(sha256::Hash::from_engine({ + let first_tlv_record = TlvStream::new(&data[..]).next().unwrap(); let mut engine = sha256::Hash::engine(); engine.input("LnNonce".as_bytes()); - engine.input(tlv_stream.peek().unwrap().record_bytes); + engine.input(first_tlv_record.record_bytes); engine })); let leaf_tag = tagged_hash_engine(sha256::Hash::hash("LnLeaf".as_bytes())); let branch_tag = tagged_hash_engine(sha256::Hash::hash("LnBranch".as_bytes())); let mut leaves = Vec::new(); - for record in tlv_stream { - if !SIGNATURE_TYPES.contains(&record.r#type) { - leaves.push(tagged_hash_from_engine(leaf_tag.clone(), &record)); - leaves.push(tagged_hash_from_engine(nonce_tag.clone(), &record.type_bytes)); - } + let tlv_stream = TlvStream::new(&data[..]); + for record in tlv_stream.skip_signatures() { + leaves.push(tagged_hash_from_engine(leaf_tag.clone(), &record.record_bytes)); + leaves.push(tagged_hash_from_engine(nonce_tag.clone(), &record.type_bytes)); } // Calculate the merkle root hash in place. @@ -144,28 +176,38 @@ fn tagged_branch_hash_from_engine( /// [`Iterator`] over a sequence of bytes yielding [`TlvRecord`]s. The input is assumed to be a /// well-formed TLV stream. -struct TlvStream<'a> { +#[derive(Clone)] +pub(super) struct TlvStream<'a> { data: io::Cursor<&'a [u8]>, } impl<'a> TlvStream<'a> { - fn new(data: &'a [u8]) -> Self { + pub fn new(data: &'a [u8]) -> Self { Self { data: io::Cursor::new(data), } } + + pub fn range(self, types: T) -> impl core::iter::Iterator> + where + T: core::ops::RangeBounds + Clone, + { + let take_range = types.clone(); + self.skip_while(move |record| !types.contains(&record.r#type)) + .take_while(move |record| take_range.contains(&record.r#type)) + } + + fn skip_signatures(self) -> core::iter::Filter, fn(&TlvRecord) -> bool> { + self.filter(|record| !SIGNATURE_TYPES.contains(&record.r#type)) + } } /// A slice into a [`TlvStream`] for a record. -struct TlvRecord<'a> { - r#type: u64, +pub(super) struct TlvRecord<'a> { + pub(super) r#type: u64, type_bytes: &'a [u8], // The entire TLV record. - record_bytes: &'a [u8], -} - -impl AsRef<[u8]> for TlvRecord<'_> { - fn as_ref(&self) -> &[u8] { &self.record_bytes } + pub(super) record_bytes: &'a [u8], } impl<'a> Iterator for TlvStream<'a> { @@ -195,14 +237,34 @@ impl<'a> Iterator for TlvStream<'a> { } } +/// Encoding for a pre-serialized TLV stream that excludes any signature TLV records. +/// +/// Panics if the wrapped bytes are not a well-formed TLV stream. +pub(super) struct WithoutSignatures<'a>(pub &'a [u8]); + +impl<'a> Writeable for WithoutSignatures<'a> { + #[inline] + fn write(&self, writer: &mut W) -> Result<(), io::Error> { + let tlv_stream = TlvStream::new(self.0); + for record in tlv_stream.skip_signatures() { + writer.write_all(record.record_bytes)?; + } + Ok(()) + } +} + #[cfg(test)] mod tests { + use super::{SIGNATURE_TYPES, TlvStream, WithoutSignatures}; + use bitcoin::hashes::{Hash, sha256}; use bitcoin::secp256k1::{KeyPair, Secp256k1, SecretKey}; + use bitcoin::secp256k1::schnorr::Signature; use core::convert::Infallible; use crate::offers::offer::{Amount, OfferBuilder}; use crate::offers::invoice_request::InvoiceRequest; use crate::offers::parse::Bech32Encode; + use crate::util::ser::Writeable; #[test] fn calculates_merkle_root_hash() { @@ -242,7 +304,9 @@ mod tests { .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))) + .sign::<_, Infallible>( + |message| Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &payer_keys)) + ) .unwrap(); assert_eq!( invoice_request.to_string(), @@ -252,6 +316,76 @@ mod tests { super::root_hash(&invoice_request.bytes[..]), sha256::Hash::from_slice(&hex::decode("608407c18ad9a94d9ea2bcdbe170b6c20c462a7833a197621c916f78cf18e624").unwrap()).unwrap(), ); + assert_eq!( + invoice_request.signature(), + Signature::from_slice(&hex::decode("b8f83ea3288cfd6ea510cdb481472575141e8d8744157f98562d162cc1c472526fdb24befefbdebab4dbb726bbd1b7d8aec057f8fa805187e5950d2bbe0e5642").unwrap()).unwrap(), + ); + } + + #[test] + fn skips_encoding_signature_tlv_records() { + let secp_ctx = Secp256k1::new(); + let recipient_pubkey = { + let secret_key = SecretKey::from_slice(&[41; 32]).unwrap(); + KeyPair::from_secret_key(&secp_ctx, &secret_key).public_key() + }; + let payer_keys = { + let secret_key = SecretKey::from_slice(&[42; 32]).unwrap(); + KeyPair::from_secret_key(&secp_ctx, &secret_key) + }; + + let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey) + .amount_msats(100) + .build_unchecked() + .request_invoice(vec![0; 8], payer_keys.public_key()).unwrap() + .build_unchecked() + .sign::<_, Infallible>( + |message| Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &payer_keys)) + ) + .unwrap(); + + let mut bytes_without_signature = Vec::new(); + WithoutSignatures(&invoice_request.bytes).write(&mut bytes_without_signature).unwrap(); + + assert_ne!(bytes_without_signature, invoice_request.bytes); + assert_eq!( + TlvStream::new(&bytes_without_signature).count(), + TlvStream::new(&invoice_request.bytes).count() - 1, + ); + } + + #[test] + fn iterates_over_tlv_stream_range() { + let secp_ctx = Secp256k1::new(); + let recipient_pubkey = { + let secret_key = SecretKey::from_slice(&[41; 32]).unwrap(); + KeyPair::from_secret_key(&secp_ctx, &secret_key).public_key() + }; + let payer_keys = { + let secret_key = SecretKey::from_slice(&[42; 32]).unwrap(); + KeyPair::from_secret_key(&secp_ctx, &secret_key) + }; + + let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey) + .amount_msats(100) + .build_unchecked() + .request_invoice(vec![0; 8], payer_keys.public_key()).unwrap() + .build_unchecked() + .sign::<_, Infallible>( + |message| Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &payer_keys)) + ) + .unwrap(); + + let tlv_stream = TlvStream::new(&invoice_request.bytes).range(0..1) + .chain(TlvStream::new(&invoice_request.bytes).range(1..80)) + .chain(TlvStream::new(&invoice_request.bytes).range(80..160)) + .chain(TlvStream::new(&invoice_request.bytes).range(160..240)) + .chain(TlvStream::new(&invoice_request.bytes).range(SIGNATURE_TYPES)) + .map(|r| r.record_bytes.to_vec()) + .flatten() + .collect::>(); + + assert_eq!(tlv_stream, invoice_request.bytes); } impl AsRef<[u8]> for InvoiceRequest {