]> git.bitcoin.ninja Git - rust-lightning/commitdiff
Adds lightning message signing/verification/pk_recovery
authorSergi Delgado Segura <sergi.delgado.s@gmail.com>
Tue, 16 Mar 2021 14:55:44 +0000 (15:55 +0100)
committerSergi Delgado Segura <sergi.delgado.s@gmail.com>
Fri, 16 Apr 2021 05:34:51 +0000 (07:34 +0200)
lightning/src/util/message_signing.rs [new file with mode: 0644]
lightning/src/util/mod.rs

diff --git a/lightning/src/util/message_signing.rs b/lightning/src/util/message_signing.rs
new file mode 100644 (file)
index 0000000..b73ba2b
--- /dev/null
@@ -0,0 +1,140 @@
+// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
+// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
+// You may not use this file except in accordance with one or both of these
+// licenses.
+
+//! Lightning message signing and verification lives here. These tools can be used to sign messages using the node's
+//! secret so receivers are sure that they come from you. You can also use this to verify that a given message comes
+//! from a specific node.
+//! Furthermore, these tools can be used to sign / verify messages using ephemeral keys not tied to node's identities.
+//!
+//! Note this is not part of the specs, but follows lnd's signing and verifying protocol, which can is defined as follows:
+//!
+//! signature = zbase32(SigRec(sha256d(("Lightning Signed Message:" + msg)))
+//! zbase32 from https://philzimmermann.com/docs/human-oriented-base-32-encoding.txt
+//! SigRec has first byte 31 + recovery id, followed by 64 byte sig.
+//!
+//! This implementation is compatible with both lnd's and c-lightning's
+//!
+//! https://lightning.readthedocs.io/lightning-signmessage.7.html
+//! https://api.lightning.community/#signmessage
+
+use crate::util::zbase32;
+use bitcoin::hashes::{sha256d, Hash};
+use bitcoin::secp256k1::recovery::{RecoverableSignature, RecoveryId};
+use bitcoin::secp256k1::{Error, Message, PublicKey, Secp256k1, SecretKey};
+
+static LN_MESSAGE_PREFIX: &[u8] = b"Lightning Signed Message:";
+
+fn sigrec_encode(sig_rec: RecoverableSignature) -> Vec<u8> {
+    let (rid, rsig) = sig_rec.serialize_compact();
+    let prefix = rid.to_i32() as u8 + 31;
+
+    [&[prefix], &rsig[..]].concat()
+}
+
+fn sigrec_decode(sig_rec: Vec<u8>) -> Result<RecoverableSignature, Error> {
+    let rsig = &sig_rec[1..];
+    let rid = sig_rec[0] as i32 - 31;
+
+    match RecoveryId::from_i32(rid) {
+        Ok(x) => RecoverableSignature::from_compact(rsig, x),
+        Err(e) => Err(e)
+    }
+}
+
+/// Creates a digital signature of a message given a SecretKey, like the node's secret.
+/// A receiver knowing the PublicKey (e.g. the node's id) and the message can be sure that the signature was generated by the caller.
+/// Signatures are EC recoverable, meaning that given the message and the signature the PublicKey of the signer can be extracted.
+pub fn sign(msg: &[u8], sk: SecretKey) -> Result<String, Error> {
+    let secp_ctx = Secp256k1::signing_only();
+    let msg_hash = sha256d::Hash::hash(&[LN_MESSAGE_PREFIX, msg].concat());
+
+    let sig = secp_ctx.sign_recoverable(&Message::from_slice(&msg_hash)?, &sk);
+    Ok(zbase32::encode(&sigrec_encode(sig)))
+}
+
+/// Recovers the PublicKey of the signer of the message given the message and the signature.
+pub fn recover_pk(msg: &[u8], sig: &str) ->  Result<PublicKey, Error> {
+    let secp_ctx = Secp256k1::verification_only();
+    let msg_hash = sha256d::Hash::hash(&[LN_MESSAGE_PREFIX, msg].concat());
+
+    match zbase32::decode(&sig) {
+        Ok(sig_rec) => {
+            match sigrec_decode(sig_rec) {
+                Ok(sig) => secp_ctx.recover(&Message::from_slice(&msg_hash)?, &sig),
+                Err(e) => Err(e)
+            }
+        },
+        Err(_) => Err(Error::InvalidSignature)
+    }
+}
+
+/// Verifies a message was signed by a PrivateKey that derives to a given PublicKey, given a message, a signature,
+/// and the PublicKey.
+pub fn verify(msg: &[u8], sig: &str, pk: PublicKey) -> bool {
+    match recover_pk(msg, sig) {
+        Ok(x) => x == pk,
+        Err(_) => false
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use std::str::FromStr;
+    use util::message_signing::{sign, recover_pk, verify};
+    use bitcoin::secp256k1::key::ONE_KEY;
+    use bitcoin::secp256k1::{PublicKey, Secp256k1};
+
+    #[test]
+    fn test_sign() {
+        let message = "test message";
+        let zbase32_sig = sign(message.as_bytes(), ONE_KEY);
+
+        assert_eq!(zbase32_sig.unwrap(), "d9tibmnic9t5y41hg7hkakdcra94akas9ku3rmmj4ag9mritc8ok4p5qzefs78c9pqfhpuftqqzhydbdwfg7u6w6wdxcqpqn4sj4e73e")
+    }
+
+    #[test]
+    fn test_recover_pk() {
+        let message = "test message";
+        let sig = "d9tibmnic9t5y41hg7hkakdcra94akas9ku3rmmj4ag9mritc8ok4p5qzefs78c9pqfhpuftqqzhydbdwfg7u6w6wdxcqpqn4sj4e73e";
+        let pk = recover_pk(message.as_bytes(), sig);
+
+        assert_eq!(pk.unwrap(), PublicKey::from_secret_key(&Secp256k1::signing_only(), &ONE_KEY))
+    }
+
+    #[test]
+    fn test_verify() {
+        let message = "another message";
+        let sig = sign(message.as_bytes(), ONE_KEY).unwrap();
+        let pk = PublicKey::from_secret_key(&Secp256k1::signing_only(), &ONE_KEY);
+
+        assert!(verify(message.as_bytes(), &sig, pk))
+    }
+
+    #[test]
+    fn test_verify_ground_truth_ish() {
+        // There are no standard tests vectors for Sign/Verify, using the same tests vectors as c-lightning to see if they are compatible.
+        // Taken from https://github.com/ElementsProject/lightning/blob/1275af6fbb02460c8eb2f00990bb0ef9179ce8f3/tests/test_misc.py#L1925-L1938
+
+        let corpus = [
+            ["@bitconner",
+             "is this compatible?",
+             "rbgfioj114mh48d8egqx8o9qxqw4fmhe8jbeeabdioxnjk8z3t1ma1hu1fiswpakgucwwzwo6ofycffbsqusqdimugbh41n1g698hr9t",
+             "02b80cabdf82638aac86948e4c06e82064f547768dcef977677b9ea931ea75bab5"],
+            ["@duck1123",
+             "hi",
+             "rnrphcjswusbacjnmmmrynh9pqip7sy5cx695h6mfu64iac6qmcmsd8xnsyczwmpqp9shqkth3h4jmkgyqu5z47jfn1q7gpxtaqpx4xg",
+             "02de60d194e1ca5947b59fe8e2efd6aadeabfb67f2e89e13ae1a799c1e08e4a43b"],
+            ["@jochemin",
+             "hi",
+             "ry8bbsopmduhxy3dr5d9ekfeabdpimfx95kagdem7914wtca79jwamtbw4rxh69hg7n6x9ty8cqk33knbxaqftgxsfsaeprxkn1k48p3",
+             "022b8ece90ee891cbcdac0c1cc6af46b73c47212d8defbce80265ac81a6b794931"],
+        ];
+
+        for c in &corpus {
+            assert!(verify(c[1].as_bytes(), c[2], PublicKey::from_str(c[3]).unwrap()))
+        }
+    }
+}
index 59b46a4f1becb4db606801f5cdc510dcc8b2d0a7..761d1fd020856ad471e5804dde23840cc1bfcc71 100644 (file)
@@ -16,6 +16,7 @@ pub mod events;
 pub mod errors;
 pub mod ser;
 pub mod zbase32;
+pub mod message_signing;
 
 pub(crate) mod byte_utils;
 pub(crate) mod chacha20;