1 // This file is Copyright its original authors, visible in version control
4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
5 // or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
7 // You may not use this file except in accordance with one or both of these
10 //! Tagged hashes for use in signature calculation and verification.
12 use bitcoin::hashes::{Hash, HashEngine, sha256};
13 use bitcoin::secp256k1::{Message, PublicKey, Secp256k1, self};
14 use bitcoin::secp256k1::schnorr::Signature;
15 use core::convert::AsRef;
17 use crate::util::ser::{BigSize, Readable, Writeable, Writer};
19 use crate::prelude::*;
21 /// Valid type range for signature TLV records.
22 const SIGNATURE_TYPES: core::ops::RangeInclusive<u64> = 240..=1000;
24 tlv_stream!(SignatureTlvStream, SignatureTlvStreamRef, SIGNATURE_TYPES, {
25 (240, signature: Signature),
28 /// A hash for use in a specific context by tweaking with a context-dependent tag as per [BIP 340]
29 /// and computed over the merkle root of a TLV stream to sign as defined in [BOLT 12].
31 /// [BIP 340]: https://github.com/bitcoin/bips/blob/master/bip-0340.mediawiki
32 /// [BOLT 12]: https://github.com/rustyrussell/lightning-rfc/blob/guilt/offers/12-offer-encoding.md#signature-calculation
33 pub struct TaggedHash(Message);
36 /// Creates a tagged hash with the given parameters.
38 /// Panics if `tlv_stream` is not a well-formed TLV stream containing at least one TLV record.
39 pub(super) fn new(tag: &str, tlv_stream: &[u8]) -> Self {
40 Self(message_digest(tag, tlv_stream))
43 /// Returns the digest to sign.
44 pub fn as_digest(&self) -> &Message {
49 impl AsRef<TaggedHash> for TaggedHash {
50 fn as_ref(&self) -> &TaggedHash {
55 /// Error when signing messages.
56 #[derive(Debug, PartialEq)]
57 pub enum SignError<E> {
58 /// User-defined error when signing the message.
60 /// Error when verifying the produced signature using the given pubkey.
61 Verification(secp256k1::Error),
64 /// Signs a [`TaggedHash`] computed over the merkle root of `message`'s TLV stream, checking if it
65 /// can be verified with the supplied `pubkey`.
67 /// Since `message` is any type that implements [`AsRef<TaggedHash>`], `sign` may be a closure that
68 /// takes a message such as [`Bolt12Invoice`] or [`InvoiceRequest`]. This allows further message
69 /// verification before signing its [`TaggedHash`].
71 /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice
72 /// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
73 pub(super) fn sign_message<F, E, T>(
74 sign: F, message: &T, pubkey: PublicKey,
75 ) -> Result<Signature, SignError<E>>
77 F: FnOnce(&T) -> Result<Signature, E>,
80 let signature = sign(message).map_err(|e| SignError::Signing(e))?;
82 let digest = message.as_ref().as_digest();
83 let pubkey = pubkey.into();
84 let secp_ctx = Secp256k1::verification_only();
85 secp_ctx.verify_schnorr(&signature, digest, &pubkey).map_err(|e| SignError::Verification(e))?;
90 /// Verifies the signature with a pubkey over the given bytes using a tagged hash as the message
93 /// Panics if `bytes` is not a well-formed TLV stream containing at least one TLV record.
94 pub(super) fn verify_signature(
95 signature: &Signature, tag: &str, bytes: &[u8], pubkey: PublicKey,
96 ) -> Result<(), secp256k1::Error> {
97 let digest = message_digest(tag, bytes);
98 let pubkey = pubkey.into();
99 let secp_ctx = Secp256k1::verification_only();
100 secp_ctx.verify_schnorr(signature, &digest, &pubkey)
103 pub(super) fn message_digest(tag: &str, bytes: &[u8]) -> Message {
104 let tag = sha256::Hash::hash(tag.as_bytes());
105 let merkle_root = root_hash(bytes);
106 Message::from_slice(&tagged_hash(tag, merkle_root)).unwrap()
109 /// Computes a merkle root hash for the given data, which must be a well-formed TLV stream
110 /// containing at least one TLV record.
111 fn root_hash(data: &[u8]) -> sha256::Hash {
112 let nonce_tag = tagged_hash_engine(sha256::Hash::from_engine({
113 let first_tlv_record = TlvStream::new(&data[..]).next().unwrap();
114 let mut engine = sha256::Hash::engine();
115 engine.input("LnNonce".as_bytes());
116 engine.input(first_tlv_record.record_bytes);
119 let leaf_tag = tagged_hash_engine(sha256::Hash::hash("LnLeaf".as_bytes()));
120 let branch_tag = tagged_hash_engine(sha256::Hash::hash("LnBranch".as_bytes()));
122 let mut leaves = Vec::new();
123 let tlv_stream = TlvStream::new(&data[..]);
124 for record in tlv_stream.skip_signatures() {
125 leaves.push(tagged_hash_from_engine(leaf_tag.clone(), &record.record_bytes));
126 leaves.push(tagged_hash_from_engine(nonce_tag.clone(), &record.type_bytes));
129 // Calculate the merkle root hash in place.
130 let num_leaves = leaves.len();
132 let step = 2 << level;
133 let offset = step / 2;
134 if offset >= num_leaves {
138 let left_branches = (0..num_leaves).step_by(step);
139 let right_branches = (offset..num_leaves).step_by(step);
140 for (i, j) in left_branches.zip(right_branches) {
141 leaves[i] = tagged_branch_hash_from_engine(branch_tag.clone(), leaves[i], leaves[j]);
145 *leaves.first().unwrap()
148 fn tagged_hash<T: AsRef<[u8]>>(tag: sha256::Hash, msg: T) -> sha256::Hash {
149 let engine = tagged_hash_engine(tag);
150 tagged_hash_from_engine(engine, msg)
153 fn tagged_hash_engine(tag: sha256::Hash) -> sha256::HashEngine {
154 let mut engine = sha256::Hash::engine();
155 engine.input(tag.as_ref());
156 engine.input(tag.as_ref());
160 fn tagged_hash_from_engine<T: AsRef<[u8]>>(mut engine: sha256::HashEngine, msg: T) -> sha256::Hash {
161 engine.input(msg.as_ref());
162 sha256::Hash::from_engine(engine)
165 fn tagged_branch_hash_from_engine(
166 mut engine: sha256::HashEngine, leaf1: sha256::Hash, leaf2: sha256::Hash,
169 engine.input(leaf1.as_ref());
170 engine.input(leaf2.as_ref());
172 engine.input(leaf2.as_ref());
173 engine.input(leaf1.as_ref());
175 sha256::Hash::from_engine(engine)
178 /// [`Iterator`] over a sequence of bytes yielding [`TlvRecord`]s. The input is assumed to be a
179 /// well-formed TLV stream.
181 pub(super) struct TlvStream<'a> {
182 data: io::Cursor<&'a [u8]>,
185 impl<'a> TlvStream<'a> {
186 pub fn new(data: &'a [u8]) -> Self {
188 data: io::Cursor::new(data),
192 pub fn range<T>(self, types: T) -> impl core::iter::Iterator<Item = TlvRecord<'a>>
194 T: core::ops::RangeBounds<u64> + Clone,
196 let take_range = types.clone();
197 self.skip_while(move |record| !types.contains(&record.r#type))
198 .take_while(move |record| take_range.contains(&record.r#type))
201 fn skip_signatures(self) -> core::iter::Filter<TlvStream<'a>, fn(&TlvRecord) -> bool> {
202 self.filter(|record| !SIGNATURE_TYPES.contains(&record.r#type))
206 /// A slice into a [`TlvStream`] for a record.
207 pub(super) struct TlvRecord<'a> {
208 pub(super) r#type: u64,
209 type_bytes: &'a [u8],
210 // The entire TLV record.
211 pub(super) record_bytes: &'a [u8],
214 impl<'a> Iterator for TlvStream<'a> {
215 type Item = TlvRecord<'a>;
217 fn next(&mut self) -> Option<Self::Item> {
218 if self.data.position() < self.data.get_ref().len() as u64 {
219 let start = self.data.position();
221 let r#type = <BigSize as Readable>::read(&mut self.data).unwrap().0;
222 let offset = self.data.position();
223 let type_bytes = &self.data.get_ref()[start as usize..offset as usize];
225 let length = <BigSize as Readable>::read(&mut self.data).unwrap().0;
226 let offset = self.data.position();
227 let end = offset + length;
229 let _value = &self.data.get_ref()[offset as usize..end as usize];
230 let record_bytes = &self.data.get_ref()[start as usize..end as usize];
232 self.data.set_position(end);
234 Some(TlvRecord { r#type, type_bytes, record_bytes })
241 /// Encoding for a pre-serialized TLV stream that excludes any signature TLV records.
243 /// Panics if the wrapped bytes are not a well-formed TLV stream.
244 pub(super) struct WithoutSignatures<'a>(pub &'a [u8]);
246 impl<'a> Writeable for WithoutSignatures<'a> {
248 fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
249 let tlv_stream = TlvStream::new(self.0);
250 for record in tlv_stream.skip_signatures() {
251 writer.write_all(record.record_bytes)?;
259 use super::{SIGNATURE_TYPES, TlvStream, WithoutSignatures};
261 use bitcoin::hashes::{Hash, sha256};
262 use bitcoin::secp256k1::{KeyPair, Secp256k1, SecretKey};
263 use bitcoin::secp256k1::schnorr::Signature;
264 use core::convert::Infallible;
265 use crate::offers::offer::{Amount, OfferBuilder};
266 use crate::offers::invoice_request::InvoiceRequest;
267 use crate::offers::parse::Bech32Encode;
268 use crate::util::ser::Writeable;
271 fn calculates_merkle_root_hash() {
272 // BOLT 12 test vectors
273 macro_rules! tlv1 { () => { "010203e8" } }
274 macro_rules! tlv2 { () => { "02080000010000020003" } }
275 macro_rules! tlv3 { () => { "03310266e4598d1d3c415f572a8488830b60f7e744ed9235eb0b1ba93283b315c0351800000000000000010000000000000002" } }
277 super::root_hash(&hex::decode(tlv1!()).unwrap()),
278 sha256::Hash::from_slice(&hex::decode("b013756c8fee86503a0b4abdab4cddeb1af5d344ca6fc2fa8b6c08938caa6f93").unwrap()).unwrap(),
281 super::root_hash(&hex::decode(concat!(tlv1!(), tlv2!())).unwrap()),
282 sha256::Hash::from_slice(&hex::decode("c3774abbf4815aa54ccaa026bff6581f01f3be5fe814c620a252534f434bc0d1").unwrap()).unwrap(),
285 super::root_hash(&hex::decode(concat!(tlv1!(), tlv2!(), tlv3!())).unwrap()),
286 sha256::Hash::from_slice(&hex::decode("ab2e79b1283b0b31e0b035258de23782df6b89a38cfa7237bde69aed1a658c5d").unwrap()).unwrap(),
291 fn calculates_merkle_root_hash_from_invoice_request() {
292 let secp_ctx = Secp256k1::new();
293 let recipient_pubkey = {
294 let secret_key = SecretKey::from_slice(&hex::decode("4141414141414141414141414141414141414141414141414141414141414141").unwrap()).unwrap();
295 KeyPair::from_secret_key(&secp_ctx, &secret_key).public_key()
298 let secret_key = SecretKey::from_slice(&hex::decode("4242424242424242424242424242424242424242424242424242424242424242").unwrap()).unwrap();
299 KeyPair::from_secret_key(&secp_ctx, &secret_key)
302 // BOLT 12 test vectors
303 let invoice_request = OfferBuilder::new("A Mathematical Treatise".into(), recipient_pubkey)
304 .amount(Amount::Currency { iso4217_code: *b"USD", amount: 100 })
306 .request_invoice(vec![0; 8], payer_keys.public_key()).unwrap()
308 .sign::<_, Infallible>(
309 |message| Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &payer_keys))
313 invoice_request.to_string(),
314 "lnr1qqyqqqqqqqqqqqqqqcp4256ypqqkgzshgysy6ct5dpjk6ct5d93kzmpq23ex2ct5d9ek293pqthvwfzadd7jejes8q9lhc4rvjxd022zv5l44g6qah82ru5rdpnpjkppqvjx204vgdzgsqpvcp4mldl3plscny0rt707gvpdh6ndydfacz43euzqhrurageg3n7kafgsek6gz3e9w52parv8gs2hlxzk95tzeswywffxlkeyhml0hh46kndmwf4m6xma3tkq2lu04qz3slje2rfthc89vss",
317 super::root_hash(&invoice_request.bytes[..]),
318 sha256::Hash::from_slice(&hex::decode("608407c18ad9a94d9ea2bcdbe170b6c20c462a7833a197621c916f78cf18e624").unwrap()).unwrap(),
321 invoice_request.signature(),
322 Signature::from_slice(&hex::decode("b8f83ea3288cfd6ea510cdb481472575141e8d8744157f98562d162cc1c472526fdb24befefbdebab4dbb726bbd1b7d8aec057f8fa805187e5950d2bbe0e5642").unwrap()).unwrap(),
327 fn skips_encoding_signature_tlv_records() {
328 let secp_ctx = Secp256k1::new();
329 let recipient_pubkey = {
330 let secret_key = SecretKey::from_slice(&[41; 32]).unwrap();
331 KeyPair::from_secret_key(&secp_ctx, &secret_key).public_key()
334 let secret_key = SecretKey::from_slice(&[42; 32]).unwrap();
335 KeyPair::from_secret_key(&secp_ctx, &secret_key)
338 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey)
341 .request_invoice(vec![0; 8], payer_keys.public_key()).unwrap()
343 .sign::<_, Infallible>(
344 |message| Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &payer_keys))
348 let mut bytes_without_signature = Vec::new();
349 WithoutSignatures(&invoice_request.bytes).write(&mut bytes_without_signature).unwrap();
351 assert_ne!(bytes_without_signature, invoice_request.bytes);
353 TlvStream::new(&bytes_without_signature).count(),
354 TlvStream::new(&invoice_request.bytes).count() - 1,
359 fn iterates_over_tlv_stream_range() {
360 let secp_ctx = Secp256k1::new();
361 let recipient_pubkey = {
362 let secret_key = SecretKey::from_slice(&[41; 32]).unwrap();
363 KeyPair::from_secret_key(&secp_ctx, &secret_key).public_key()
366 let secret_key = SecretKey::from_slice(&[42; 32]).unwrap();
367 KeyPair::from_secret_key(&secp_ctx, &secret_key)
370 let invoice_request = OfferBuilder::new("foo".into(), recipient_pubkey)
373 .request_invoice(vec![0; 8], payer_keys.public_key()).unwrap()
375 .sign::<_, Infallible>(
376 |message| Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &payer_keys))
380 let tlv_stream = TlvStream::new(&invoice_request.bytes).range(0..1)
381 .chain(TlvStream::new(&invoice_request.bytes).range(1..80))
382 .chain(TlvStream::new(&invoice_request.bytes).range(80..160))
383 .chain(TlvStream::new(&invoice_request.bytes).range(160..240))
384 .chain(TlvStream::new(&invoice_request.bytes).range(SIGNATURE_TYPES))
385 .map(|r| r.record_bytes.to_vec())
387 .collect::<Vec<u8>>();
389 assert_eq!(tlv_stream, invoice_request.bytes);
392 impl AsRef<[u8]> for InvoiceRequest {
393 fn as_ref(&self) -> &[u8] {
398 impl Bech32Encode for InvoiceRequest {
399 const BECH32_HRP: &'static str = "lnr";
402 impl core::fmt::Display for InvoiceRequest {
403 fn fmt(&self, f: &mut core::fmt::Formatter) -> Result<(), core::fmt::Error> {
404 self.fmt_bech32_str(f)