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Merged
optout21 merged 1 commit into from
Jan 12, 2026
Merged

Add method to verify a Schnorr signature #15

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8 changes: 8 additions & 0 deletions lib-py/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -78,6 +78,13 @@ pub fn sign_schnorr_with_nonce(msg: String, nonce_sec_hex: String, index: u32) -
.map_err(|e| PyErr::new::<PyException, _>(e))
}

/// Verify a Schnorr signature over a message, using a child key
#[pyfunction]
pub fn verify_schnorr(msg: String, signature_hex: String, index: u32) -> PyResult<bool> {
dlccryptlib::verify_schnorr(&msg, &signature_hex, index)
.map_err(|e| PyErr::new::<PyException, _>(e))
}

/// Combine a number of public keys into one
#[pyfunction]
pub fn combine_pubkeys(keys_hex: String) -> PyResult<String> {
Expand Down Expand Up @@ -182,6 +189,7 @@ fn dlccryptlib_py(_py: Python, m: &Bound<'_, PyModule>) -> PyResult<()> {
m.add_function(wrap_pyfunction!(sign_hash_ecdsa, m)?)?;
m.add_function(wrap_pyfunction!(create_deterministic_nonce, m)?)?;
m.add_function(wrap_pyfunction!(sign_schnorr_with_nonce, m)?)?;
m.add_function(wrap_pyfunction!(verify_schnorr, m)?)?;
m.add_function(wrap_pyfunction!(combine_pubkeys, m)?)?;
m.add_function(wrap_pyfunction!(combine_seckeys, m)?)?;
m.add_function(wrap_pyfunction!(create_cet_adaptor_sigs, m)?)?;
Expand Down
24 changes: 24 additions & 0 deletions src/adaptor_signature.rs
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Expand Up @@ -153,6 +153,30 @@ fn message_hash(msg: &str) -> Result<Message, String> {
.map_err(|e| e.to_string())
}

/// Verify a Schnorr signature on a message
pub(crate) fn verify_schnorr<S: Signing>(
secp: &Secp256k1<S>,
sig: &SchnorrSignature,
public_key: &XOnlyPublicKey,
msg: &str,
) -> Result<bool, String> {
let msg_hash = sha256::Hash::hash(msg.as_bytes()).to_byte_array();
let msg_msg = Message::from_digest(msg_hash);

let res_num: i32;
unsafe {
res_num = secp256k1_sys::secp256k1_schnorrsig_verify(
secp.ctx().as_ref(),
sig.as_c_ptr(),
msg_msg.as_c_ptr(),
32_usize,
public_key.as_c_ptr(),
);
}

Ok(res_num != 0)
}

pub(crate) fn create_digit_adaptor_sig_point<S: Signing + Verification>(
secp: &Secp256k1<S>,
oracle_pubkey: &PublicKey,
Expand Down
17 changes: 12 additions & 5 deletions src/lib.rs
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Expand Up @@ -94,10 +94,7 @@ pub fn sign_hash_ecdsa(
Ok(sig.to_lower_hex_string())
}

pub fn create_deterministic_nonce(
event_id: &str,
index: u32,
) -> Result<(String, String), String> {
pub fn create_deterministic_nonce(event_id: &str, index: u32) -> Result<(String, String), String> {
let (sk, pk) = global_lib()
.read()
.unwrap()
Expand All @@ -120,6 +117,17 @@ pub fn sign_schnorr_with_nonce(
Ok(sig.to_string())
}

// Schnorr signature verification
pub fn verify_schnorr(msg: &str, signature_hex: &str, index: u32) -> Result<bool, String> {
let signature = schnorr_sig_from_hex(signature_hex)
.map_err(|e| format!("Error in signature hex string {}", e))?;
let res = global_lib()
.read()
.unwrap()
.verify_schnorr(msg, &signature, index)?;
Ok(res)
}

pub fn combine_pubkeys(keys_hex: &str) -> Result<String, String> {
let keys_split: Vec<_> = keys_hex.split(" ").collect();
let mut keys = Vec::<PublicKey>::with_capacity(keys_split.len());
Expand Down Expand Up @@ -557,4 +565,3 @@ fn error_as_cstr_prefix(error: String) -> *mut c_char {
.unwrap()
.into_raw()
}

13 changes: 12 additions & 1 deletion src/lib_struct.rs
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Expand Up @@ -4,7 +4,7 @@

use crate::adaptor_signature::{
create_cet_adaptor_signatures, create_final_cet_signatures, sign_hash_ecdsa_with_key,
sign_schnorr_with_nonce_sec, verify_cet_adaptor_signatures,
sign_schnorr_with_nonce_sec, verify_cet_adaptor_signatures, verify_schnorr,
};
use crate::hd_wallet_storage::HDWalletStorage;

Expand Down Expand Up @@ -151,6 +151,17 @@ impl Lib {
sign_schnorr_with_nonce_sec(&self.secp, &kp, msg, nonce_sec)
}

/// Verify a Schnorr signature on a message using Schnorr, using a child key
pub(crate) fn verify_schnorr(
&self,
msg: &str,
signature: &SchnorrSignature,
index: u32,
) -> Result<bool, String> {
let pubkey = self.get_child_public_key(index)?.x_only_public_key().0;
verify_schnorr(&self.secp, signature, &pubkey, msg)
}

pub(crate) fn combine_seckeys(secrets: &Vec<SecretKey>) -> Result<SecretKey, String> {
if secrets.len() == 0 {
return Err("At least one key is required".to_string());
Expand Down
34 changes: 31 additions & 3 deletions src/test_lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,9 +4,9 @@

use crate::adaptor_signature::verify_ecdsa_signature;
use crate::{
combine_pubkeys, combine_seckeys, create_deterministic_nonce,
get_public_key, init_with_entropy, keypair_from_sec_key_hex,
sign_schnorr_with_nonce, verify_public_key, Lib,
combine_pubkeys, combine_seckeys, create_deterministic_nonce, get_public_key,
init_with_entropy, keypair_from_sec_key_hex, sign_schnorr_with_nonce, verify_public_key,
verify_schnorr, Lib,
};
use bitcoin::hex::FromHex;
use bitcoin::secp256k1::PublicKey;
Expand Down Expand Up @@ -145,6 +145,34 @@ fn test_sign_schnorr_with_nonce() {
assert_eq!(sig3.to_string(), "4578740620e7a2c56eabea07c835dba35e832115930d023d0a7778652fbbf7d97a9f4a207dcb1456f1b0f57c4856085c32c79f4efce81cd276c272190aab5e3c");
}

#[test]
fn test_verify_schnorr() {
let _xpub = init_with_entropy(DUMMY_ENTROPY_STR, DEFAULT_NETWORK).unwrap();

let msg = "This is a message";

// Constant signature
let sig1 = "ff4cb99e0a9be8ec7dea1e51904cf22f71717c19fc3e7dcbc8346eb28bebffbb892c4c41e05c2383efda00f5acc9c7f3622d88a90630cd62d49db598c8ce10b9";
let verify_res = verify_schnorr(msg, &sig1, 0).unwrap();
assert_eq!(verify_res, true);

// Signature created here
let nonce = "0123450000000000006897528962743076432965432697856340567500000100";
let sig = sign_schnorr_with_nonce(msg, nonce, 0).unwrap();

let verify_res = verify_schnorr(msg, &sig, 0).unwrap();
assert_eq!(verify_res, true);

// Verify with different key index
let verify_res = verify_schnorr(msg, &sig, 1).unwrap();
assert_eq!(verify_res, false);

// Verify with a different message
let msg2 = "This is ANOTHER message";
let verify_res = verify_schnorr(msg2, &sig, 0).unwrap();
assert_eq!(verify_res, false);
}

fn create_dummy_pubkey(index: u8) -> PublicKey {
let sechex = format!(
"012345000000000000689752896274307643296543269785634056750000000{}",
Expand Down