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Merge #706: Make schnorr sign/verify accept a message slice instead o…
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…f 32 bytes `Message`

df98b16 Make schnorr sign/verify accept a message slice (Elichai Turkel)

Pull request description:

  As discussed on #702 and on IRC,
  BIP340 has evolved from supporting only "pre-hashed" 32 byte messages, to supporting messages of "any length" and as such we should allow the users to pass a message of any length.
  Note that passing exactly 32 bytes will make the API behave exactly as before (ie it will produce the same signatures).

  I added all the test vectors from: https://github.com/bitcoin/bips/blob/master/bip-0340/test-vectors.csv To make sure the API is correct even for empty messages and shorter/longer ones :)

ACKs for top commit:
  Kixunil:
    ACK df98b16
  apoelstra:
    ACK df98b16 thanks for all the new test vectors\!

Tree-SHA512: bd99ea8e17fcc6fd71ad39a87c7c21761f325006998a61b33b6f2abc9f892f90a4236bd25615cb34dc83214a70dcdd34ce3e7cece7d6f971c3843505356c97c5
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@apoelstra
apoelstra committed Jul 5, 2024
2 parents 30dda2c + df98b16 commit ad9d9d0
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Showing 2 changed files with 225 additions and 23 deletions.
6 changes: 3 additions & 3 deletions src/key.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -958,8 +958,8 @@ impl Keypair {
/// Constructs an schnorr signature for `msg` using the global [`SECP256K1`] context.
#[inline]
#[cfg(all(feature = "global-context", feature = "rand-std"))]
pub fn sign_schnorr(&self, msg: Message) -> schnorr::Signature {
SECP256K1.sign_schnorr(&msg, self)
pub fn sign_schnorr(&self, msg: &[u8]) -> schnorr::Signature {
SECP256K1.sign_schnorr(msg, self)
}

/// Attempts to erase the secret within the underlying array.
Expand Down Expand Up @@ -1316,7 +1316,7 @@ impl XOnlyPublicKey {
pub fn verify<C: Verification>(
&self,
secp: &Secp256k1<C>,
msg: &Message,
msg: &[u8],
sig: &schnorr::Signature,
) -> Result<(), Error> {
secp.verify_schnorr(sig, msg, self)
Expand Down
242 changes: 222 additions & 20 deletions src/schnorr.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -7,12 +7,13 @@ use core::{fmt, ptr, str};

#[cfg(feature = "rand")]
use rand::{CryptoRng, Rng};
use secp256k1_sys::SchnorrSigExtraParams;

use crate::ffi::{self, CPtr};
use crate::key::{Keypair, XOnlyPublicKey};
#[cfg(feature = "global-context")]
use crate::SECP256K1;
use crate::{constants, from_hex, Error, Message, Secp256k1, Signing, Verification};
use crate::{constants, from_hex, Error, Secp256k1, Signing, Verification};

/// Represents a schnorr signature.
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
Expand Down Expand Up @@ -93,28 +94,30 @@ impl Signature {
/// Verifies a schnorr signature for `msg` using `pk` and the global [`SECP256K1`] context.
#[inline]
#[cfg(feature = "global-context")]
pub fn verify(&self, msg: &Message, pk: &XOnlyPublicKey) -> Result<(), Error> {
pub fn verify(&self, msg: &[u8], pk: &XOnlyPublicKey) -> Result<(), Error> {
SECP256K1.verify_schnorr(self, msg, pk)
}
}

impl<C: Signing> Secp256k1<C> {
fn sign_schnorr_helper(
&self,
msg: &Message,
msg: &[u8],
keypair: &Keypair,
nonce_data: *const ffi::types::c_uchar,
) -> Signature {
unsafe {
let mut sig = [0u8; constants::SCHNORR_SIGNATURE_SIZE];
let extra = SchnorrSigExtraParams::new(None, nonce_data.cast());
assert_eq!(
1,
ffi::secp256k1_schnorrsig_sign(
ffi::secp256k1_schnorrsig_sign_custom(
self.ctx.as_ptr(),
sig.as_mut_c_ptr(),
msg.as_c_ptr(),
msg.len(),
keypair.as_c_ptr(),
nonce_data,
&extra,
)
);

Expand All @@ -125,19 +128,19 @@ impl<C: Signing> Secp256k1<C> {
/// Creates a schnorr signature internally using the [`rand::rngs::ThreadRng`] random number
/// generator to generate the auxiliary random data.
#[cfg(feature = "rand-std")]
pub fn sign_schnorr(&self, msg: &Message, keypair: &Keypair) -> Signature {
pub fn sign_schnorr(&self, msg: &[u8], keypair: &Keypair) -> Signature {
self.sign_schnorr_with_rng(msg, keypair, &mut rand::thread_rng())
}

/// Creates a schnorr signature without using any auxiliary random data.
pub fn sign_schnorr_no_aux_rand(&self, msg: &Message, keypair: &Keypair) -> Signature {
pub fn sign_schnorr_no_aux_rand(&self, msg: &[u8], keypair: &Keypair) -> Signature {
self.sign_schnorr_helper(msg, keypair, ptr::null())
}

/// Creates a schnorr signature using the given auxiliary random data.
pub fn sign_schnorr_with_aux_rand(
&self,
msg: &Message,
msg: &[u8],
keypair: &Keypair,
aux_rand: &[u8; 32],
) -> Signature {
Expand All @@ -149,7 +152,7 @@ impl<C: Signing> Secp256k1<C> {
#[cfg(feature = "rand")]
pub fn sign_schnorr_with_rng<R: Rng + CryptoRng>(
&self,
msg: &Message,
msg: &[u8],
keypair: &Keypair,
rng: &mut R,
) -> Signature {
Expand All @@ -164,15 +167,15 @@ impl<C: Verification> Secp256k1<C> {
pub fn verify_schnorr(
&self,
sig: &Signature,
msg: &Message,
msg: &[u8],
pubkey: &XOnlyPublicKey,
) -> Result<(), Error> {
unsafe {
let ret = ffi::secp256k1_schnorrsig_verify(
self.ctx.as_ptr(),
sig.as_c_ptr(),
msg.as_c_ptr(),
32,
msg.len(),
pubkey.as_c_ptr(),
);

Expand Down Expand Up @@ -235,9 +238,7 @@ mod tests {
}

#[cfg(feature = "rand-std")]
fn sign_helper(
sign: fn(&Secp256k1<crate::All>, &Message, &Keypair, &mut ThreadRng) -> Signature,
) {
fn sign_helper(sign: fn(&Secp256k1<crate::All>, &[u8], &Keypair, &mut ThreadRng) -> Signature) {
let secp = Secp256k1::new();

let mut rng = rand::thread_rng();
Expand All @@ -246,7 +247,6 @@ mod tests {

for _ in 0..100 {
let msg = crate::random_32_bytes(&mut rand::thread_rng());
let msg = Message::from_digest_slice(&msg).unwrap();

let sig = sign(&secp, &msg, &kp, &mut rng);

Expand All @@ -260,8 +260,7 @@ mod tests {
fn schnorr_sign() {
let secp = Secp256k1::new();

let hex_msg = hex_32!("E48441762FB75010B2AA31A512B62B4148AA3FB08EB0765D76B252559064A614");
let msg = Message::from_digest_slice(&hex_msg).unwrap();
let msg = hex_32!("E48441762FB75010B2AA31A512B62B4148AA3FB08EB0765D76B252559064A614");
let sk = Keypair::from_seckey_str(
&secp,
"688C77BC2D5AAFF5491CF309D4753B732135470D05B7B2CD21ADD0744FE97BEF",
Expand All @@ -282,8 +281,7 @@ mod tests {
fn schnorr_verify() {
let secp = Secp256k1::new();

let hex_msg = hex_32!("E48441762FB75010B2AA31A512B62B4148AA3FB08EB0765D76B252559064A614");
let msg = Message::from_digest_slice(&hex_msg).unwrap();
let msg = hex_32!("E48441762FB75010B2AA31A512B62B4148AA3FB08EB0765D76B252559064A614");
let sig = Signature::from_str("6470FD1303DDA4FDA717B9837153C24A6EAB377183FC438F939E0ED2B620E9EE5077C4A8B8DCA28963D772A94F5F0DDF598E1C47C137F91933274C7C3EDADCE8").unwrap();
let pubkey = XOnlyPublicKey::from_str(
"B33CC9EDC096D0A83416964BD3C6247B8FECD256E4EFA7870D2C854BDEB33390",
Expand Down Expand Up @@ -462,7 +460,7 @@ mod tests {

let s = Secp256k1::new();

let msg = Message::from_digest_slice(&[1; 32]).unwrap();
let msg = [1; 32];
let keypair = Keypair::from_seckey_slice(&s, &[2; 32]).unwrap();
let aux = [3u8; 32];
let sig = s.sign_schnorr_with_aux_rand(&msg, &keypair, &aux);
Expand Down Expand Up @@ -506,4 +504,208 @@ mod tests {
assert_tokens(&pk.readable(), &[Token::Str(PK_STR)]);
assert_tokens(&pk.readable(), &[Token::String(PK_STR)]);
}

#[test]
#[cfg(feature = "alloc")]
#[cfg(not(secp256k1_fuzz))] // fixed sig vectors can't work with fuzz-sigs
fn bip340_test_vectors() {
struct TestVector {
secret_key: Option<[u8; 32]>,
public_key: [u8; 32],
aux_rand: Option<[u8; 32]>,
message: Vec<u8>,
signature: [u8; 64],
should_fail_verify: bool,
}
fn hex_arr<T: From<[u8; N]>, const N: usize>(s: &str) -> T {
let mut out = [0; N];
from_hex(s, &mut out).unwrap();
out.into()
}
let hex_vec = |s: &str| {
let mut v = vec![0u8; s.len() / 2];
from_hex(s, v.as_mut_slice()).unwrap();
v
};

let vectors = [
TestVector {
secret_key: hex_arr("0000000000000000000000000000000000000000000000000000000000000003"),
public_key: hex_arr("F9308A019258C31049344F85F89D5229B531C845836F99B08601F113BCE036F9"),
aux_rand: hex_arr("0000000000000000000000000000000000000000000000000000000000000000"),
message: hex_vec("0000000000000000000000000000000000000000000000000000000000000000"),
signature: hex_arr("E907831F80848D1069A5371B402410364BDF1C5F8307B0084C55F1CE2DCA821525F66A4A85EA8B71E482A74F382D2CE5EBEEE8FDB2172F477DF4900D310536C0"),
should_fail_verify: false,
},
TestVector {
secret_key: hex_arr("B7E151628AED2A6ABF7158809CF4F3C762E7160F38B4DA56A784D9045190CFEF"),
public_key: hex_arr("DFF1D77F2A671C5F36183726DB2341BE58FEAE1DA2DECED843240F7B502BA659"),
aux_rand: hex_arr("0000000000000000000000000000000000000000000000000000000000000001"),
message: hex_vec("243F6A8885A308D313198A2E03707344A4093822299F31D0082EFA98EC4E6C89"),
signature: hex_arr("6896BD60EEAE296DB48A229FF71DFE071BDE413E6D43F917DC8DCF8C78DE33418906D11AC976ABCCB20B091292BFF4EA897EFCB639EA871CFA95F6DE339E4B0A"),
should_fail_verify: false,
},
TestVector {
secret_key: hex_arr("C90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74020BBEA63B14E5C9"),
public_key: hex_arr("DD308AFEC5777E13121FA72B9CC1B7CC0139715309B086C960E18FD969774EB8"),
aux_rand: hex_arr("C87AA53824B4D7AE2EB035A2B5BBBCCC080E76CDC6D1692C4B0B62D798E6D906"),
message: hex_vec("7E2D58D8B3BCDF1ABADEC7829054F90DDA9805AAB56C77333024B9D0A508B75C"),
signature: hex_arr("5831AAEED7B44BB74E5EAB94BA9D4294C49BCF2A60728D8B4C200F50DD313C1BAB745879A5AD954A72C45A91C3A51D3C7ADEA98D82F8481E0E1E03674A6F3FB7"),
should_fail_verify: false,
},
TestVector {
secret_key: hex_arr("0B432B2677937381AEF05BB02A66ECD012773062CF3FA2549E44F58ED2401710"),
public_key: hex_arr("25D1DFF95105F5253C4022F628A996AD3A0D95FBF21D468A1B33F8C160D8F517"),
aux_rand: hex_arr("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"),
message: hex_vec("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"),
signature: hex_arr("7EB0509757E246F19449885651611CB965ECC1A187DD51B64FDA1EDC9637D5EC97582B9CB13DB3933705B32BA982AF5AF25FD78881EBB32771FC5922EFC66EA3"),
should_fail_verify: false,
},
TestVector {
secret_key: None,
public_key: hex_arr("D69C3509BB99E412E68B0FE8544E72837DFA30746D8BE2AA65975F29D22DC7B9"),
aux_rand: None,
message: hex_vec("4DF3C3F68FCC83B27E9D42C90431A72499F17875C81A599B566C9889B9696703"),
signature: hex_arr("00000000000000000000003B78CE563F89A0ED9414F5AA28AD0D96D6795F9C6376AFB1548AF603B3EB45C9F8207DEE1060CB71C04E80F593060B07D28308D7F4"),
should_fail_verify: false,
},
TestVector {
secret_key: None,
public_key: hex_arr("EEFDEA4CDB677750A420FEE807EACF21EB9898AE79B9768766E4FAA04A2D4A34"),
aux_rand: None,
message: hex_vec("243F6A8885A308D313198A2E03707344A4093822299F31D0082EFA98EC4E6C89"),
signature: hex_arr("6CFF5C3BA86C69EA4B7376F31A9BCB4F74C1976089B2D9963DA2E5543E17776969E89B4C5564D00349106B8497785DD7D1D713A8AE82B32FA79D5F7FC407D39B"),
should_fail_verify: true,
},
TestVector {
secret_key: None,
public_key: hex_arr("DFF1D77F2A671C5F36183726DB2341BE58FEAE1DA2DECED843240F7B502BA659"),
aux_rand: None,
message: hex_vec("243F6A8885A308D313198A2E03707344A4093822299F31D0082EFA98EC4E6C89"),
signature: hex_arr("FFF97BD5755EEEA420453A14355235D382F6472F8568A18B2F057A14602975563CC27944640AC607CD107AE10923D9EF7A73C643E166BE5EBEAFA34B1AC553E2"),
should_fail_verify: true,
},
TestVector {
secret_key: None,
public_key: hex_arr("DFF1D77F2A671C5F36183726DB2341BE58FEAE1DA2DECED843240F7B502BA659"),
aux_rand: None,
message: hex_vec("243F6A8885A308D313198A2E03707344A4093822299F31D0082EFA98EC4E6C89"),
signature: hex_arr("1FA62E331EDBC21C394792D2AB1100A7B432B013DF3F6FF4F99FCB33E0E1515F28890B3EDB6E7189B630448B515CE4F8622A954CFE545735AAEA5134FCCDB2BD"),
should_fail_verify: true,
},
TestVector {
secret_key: None,
public_key: hex_arr("DFF1D77F2A671C5F36183726DB2341BE58FEAE1DA2DECED843240F7B502BA659"),
aux_rand: None,
message: hex_vec("243F6A8885A308D313198A2E03707344A4093822299F31D0082EFA98EC4E6C89"),
signature: hex_arr("6CFF5C3BA86C69EA4B7376F31A9BCB4F74C1976089B2D9963DA2E5543E177769961764B3AA9B2FFCB6EF947B6887A226E8D7C93E00C5ED0C1834FF0D0C2E6DA6"),
should_fail_verify: true,
},
TestVector {
secret_key: None,
public_key: hex_arr("DFF1D77F2A671C5F36183726DB2341BE58FEAE1DA2DECED843240F7B502BA659"),
aux_rand: None,
message: hex_vec("243F6A8885A308D313198A2E03707344A4093822299F31D0082EFA98EC4E6C89"),
signature: hex_arr("0000000000000000000000000000000000000000000000000000000000000000123DDA8328AF9C23A94C1FEECFD123BA4FB73476F0D594DCB65C6425BD186051"),
should_fail_verify: true,
},
TestVector {
secret_key: None,
public_key: hex_arr("DFF1D77F2A671C5F36183726DB2341BE58FEAE1DA2DECED843240F7B502BA659"),
aux_rand: None,
message: hex_vec("243F6A8885A308D313198A2E03707344A4093822299F31D0082EFA98EC4E6C89"),
signature: hex_arr("00000000000000000000000000000000000000000000000000000000000000017615FBAF5AE28864013C099742DEADB4DBA87F11AC6754F93780D5A1837CF197"),
should_fail_verify: true,
},
TestVector {
secret_key: None,
public_key: hex_arr("DFF1D77F2A671C5F36183726DB2341BE58FEAE1DA2DECED843240F7B502BA659"),
aux_rand: None,
message: hex_vec("243F6A8885A308D313198A2E03707344A4093822299F31D0082EFA98EC4E6C89"),
signature: hex_arr("4A298DACAE57395A15D0795DDBFD1DCB564DA82B0F269BC70A74F8220429BA1D69E89B4C5564D00349106B8497785DD7D1D713A8AE82B32FA79D5F7FC407D39B"),
should_fail_verify: true,
},
TestVector {
secret_key: None,
public_key: hex_arr("DFF1D77F2A671C5F36183726DB2341BE58FEAE1DA2DECED843240F7B502BA659"),
aux_rand: None,
message: hex_vec("243F6A8885A308D313198A2E03707344A4093822299F31D0082EFA98EC4E6C89"),
signature: hex_arr("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEFFFFFC2F69E89B4C5564D00349106B8497785DD7D1D713A8AE82B32FA79D5F7FC407D39B"),
should_fail_verify: true,
},
TestVector {
secret_key: None,
public_key: hex_arr("DFF1D77F2A671C5F36183726DB2341BE58FEAE1DA2DECED843240F7B502BA659"),
aux_rand: None,
message: hex_vec("243F6A8885A308D313198A2E03707344A4093822299F31D0082EFA98EC4E6C89"),
signature: hex_arr("6CFF5C3BA86C69EA4B7376F31A9BCB4F74C1976089B2D9963DA2E5543E177769FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141"),
should_fail_verify: true,
},
TestVector {
secret_key: None,
public_key: hex_arr("778CAA53B4393AC467774D09497A87224BF9FAB6F6E68B23086497324D6FD117"),
aux_rand: None,
message: hex_vec("243F6A8885A308D313198A2E03707344A4093822299F31D0082EFA98EC4E6C89"),
signature: hex_arr("6CFF5C3BA86C69EA4B7376F31A9BCB4F74C1976089B2D9963DA2E5543E17776969E89B4C5564D00349106B8497785DD7D1D713A8AE82B32FA79D5F7FC407D39B"),
should_fail_verify: true,
},
TestVector {
secret_key: hex_arr("0340034003400340034003400340034003400340034003400340034003400340"),
public_key: hex_arr("778CAA53B4393AC467774D09497A87224BF9FAB6F6E68B23086497324D6FD117"),
aux_rand: hex_arr("0000000000000000000000000000000000000000000000000000000000000000"),
message: hex_vec(""),
signature: hex_arr("71535DB165ECD9FBBC046E5FFAEA61186BB6AD436732FCCC25291A55895464CF6069CE26BF03466228F19A3A62DB8A649F2D560FAC652827D1AF0574E427AB63"),
should_fail_verify: false,
},
TestVector {
secret_key: hex_arr("0340034003400340034003400340034003400340034003400340034003400340"),
public_key: hex_arr("778CAA53B4393AC467774D09497A87224BF9FAB6F6E68B23086497324D6FD117"),
aux_rand: hex_arr("0000000000000000000000000000000000000000000000000000000000000000"),
message: hex_vec("11"),
signature: hex_arr("08A20A0AFEF64124649232E0693C583AB1B9934AE63B4C3511F3AE1134C6A303EA3173BFEA6683BD101FA5AA5DBC1996FE7CACFC5A577D33EC14564CEC2BACBF"),
should_fail_verify: false,
},
TestVector {
secret_key: hex_arr("0340034003400340034003400340034003400340034003400340034003400340"),
public_key: hex_arr("778CAA53B4393AC467774D09497A87224BF9FAB6F6E68B23086497324D6FD117"),
aux_rand: hex_arr("0000000000000000000000000000000000000000000000000000000000000000"),
message: hex_vec("0102030405060708090A0B0C0D0E0F1011"),
signature: hex_arr("5130F39A4059B43BC7CAC09A19ECE52B5D8699D1A71E3C52DA9AFDB6B50AC370C4A482B77BF960F8681540E25B6771ECE1E5A37FD80E5A51897C5566A97EA5A5"),
should_fail_verify: false,
},
TestVector {
secret_key: hex_arr("0340034003400340034003400340034003400340034003400340034003400340"),
public_key: hex_arr("778CAA53B4393AC467774D09497A87224BF9FAB6F6E68B23086497324D6FD117"),
aux_rand: hex_arr("0000000000000000000000000000000000000000000000000000000000000000"),
message: hex_vec("99999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999"),
signature: hex_arr("403B12B0D8555A344175EA7EC746566303321E5DBFA8BE6F091635163ECA79A8585ED3E3170807E7C03B720FC54C7B23897FCBA0E9D0B4A06894CFD249F22367"),
should_fail_verify: false,
},
];
let secp = Secp256k1::new();

for TestVector {
secret_key,
public_key,
aux_rand,
message,
signature,
should_fail_verify,
} in vectors
{
if let (Some(secret_key), Some(aux_rand)) = (secret_key, aux_rand) {
let keypair = Keypair::from_seckey_slice(&secp, &secret_key).unwrap();
assert_eq!(keypair.x_only_public_key().0.serialize(), public_key);
let sig = secp.sign_schnorr_with_aux_rand(&message, &keypair, &aux_rand);
assert_eq!(sig.serialize(), signature);
}
let sig = Signature::from_slice(&signature).unwrap();
let is_verified = if let Ok(pubkey) = XOnlyPublicKey::from_slice(&public_key) {
secp.verify_schnorr(&sig, &message, &pubkey).is_ok()
} else {
false
};
assert_eq!(is_verified, !should_fail_verify);
}
}
}

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