Rename tweak_add_assign -> add_tweak

We now have a method `add_tweak` on the `SecretKey` and `PublicKey`. We
can add similar methods that consumes self and return the tweaked key
for the `KeyPair` and `XOnlyPublicKey` types.

The justification for doing so is that a local variable that calls
`tweak_add_assign` changes in meaning but the identifier remains the
same, this leads to cumbersome renaming of the local variable.

The tweaking done to the `KeyPair` is actually done via the xonly public
key not the public key. To reflect this call the method
`add_xonly_tweak`, this is similar to how it is named in secp
`secp256k1_keypair_xonly_tweak_add`.
This commit is contained in:
Tobin Harding 2022-04-06 15:24:23 +10:00 committed by Tobin C. Harding
parent b9d08db8eb
commit 5eb2d745b7
1 changed files with 53 additions and 24 deletions

View File

@ -894,6 +894,18 @@ impl KeyPair {
/// Tweaks a keypair by adding the given tweak to the secret key and updating the public key
/// accordingly.
#[inline]
#[deprecated(since = "0.23.0", note = "Use add_xonly_tweak instead")]
pub fn tweak_add_assign<C: Verification>(
&mut self,
secp: &Secp256k1<C>,
tweak: &Scalar,
) -> Result<(), Error> {
*self = self.add_xonly_tweak(secp, tweak)?;
Ok(())
}
/// Tweaks a keypair by first converting the public key to an xonly key and tweaking it.
///
/// # Errors
///
@ -913,16 +925,16 @@ impl KeyPair {
/// let tweak = Scalar::random();
///
/// let mut key_pair = KeyPair::new(&secp, &mut thread_rng());
/// key_pair.tweak_add_assign(&secp, &tweak).expect("Improbable to fail with a randomly generated tweak");
/// let tweaked = key_pair.add_xonly_tweak(&secp, &tweak).expect("Improbable to fail with a randomly generated tweak");
/// # }
/// ```
// TODO: Add checked implementation
#[inline]
pub fn tweak_add_assign<C: Verification>(
&mut self,
pub fn add_xonly_tweak<C: Verification>(
mut self,
secp: &Secp256k1<C>,
tweak: &Scalar,
) -> Result<(), Error> {
) -> Result<KeyPair, Error> {
unsafe {
let err = ffi::secp256k1_keypair_xonly_tweak_add(
secp.ctx,
@ -933,7 +945,7 @@ impl KeyPair {
return Err(Error::InvalidTweak);
}
Ok(())
Ok(self)
}
}
@ -1166,12 +1178,24 @@ impl XOnlyPublicKey {
}
/// Tweaks an x-only PublicKey by adding the generator multiplied with the given tweak to it.
#[deprecated(since = "0.23.0", note = "Use add_tweak instead")]
pub fn tweak_add_assign<V: Verification>(
&mut self,
secp: &Secp256k1<V>,
tweak: &Scalar,
) -> Result<Parity, Error> {
let (tweaked, parity) = self.add_tweak(secp, tweak)?;
*self = tweaked;
Ok(parity)
}
/// Tweaks an [`XOnlyPublicKey`] by adding the generator multiplied with the given tweak to it.
///
/// # Returns
///
/// An opaque type representing the parity of the tweaked key, this should be provided to
/// `tweak_add_check` which can be used to verify a tweak more efficiently than regenerating
/// it and checking equality.
/// The newly tweaked key plus an opaque type representing the parity of the tweaked key, this
/// should be provided to `tweak_add_check` which can be used to verify a tweak more efficiently
/// than regenerating it and checking equality.
///
/// # Errors
///
@ -1181,22 +1205,22 @@ impl XOnlyPublicKey {
///
/// ```
/// # #[cfg(all(feature = "std", feature = "rand-std"))] {
/// use secp256k1::{Secp256k1, KeyPair, Scalar};
/// use secp256k1::{Secp256k1, KeyPair, Scalar, XOnlyPublicKey};
/// use secp256k1::rand::{RngCore, thread_rng};
///
/// let secp = Secp256k1::new();
/// let tweak = Scalar::random();
///
/// let mut key_pair = KeyPair::new(&secp, &mut thread_rng());
/// let (mut public_key, _parity) = key_pair.x_only_public_key();
/// public_key.tweak_add_assign(&secp, &tweak).expect("Improbable to fail with a randomly generated tweak");
/// let (xonly, _parity) = key_pair.x_only_public_key();
/// let tweaked = xonly.add_tweak(&secp, &tweak).expect("Improbable to fail with a randomly generated tweak");
/// # }
/// ```
pub fn tweak_add_assign<V: Verification>(
&mut self,
pub fn add_tweak<V: Verification>(
mut self,
secp: &Secp256k1<V>,
tweak: &Scalar,
) -> Result<Parity, Error> {
) -> Result<(XOnlyPublicKey, Parity), Error> {
let mut pk_parity = 0;
unsafe {
let mut pubkey = ffi::PublicKey::new();
@ -1220,7 +1244,8 @@ impl XOnlyPublicKey {
return Err(Error::InvalidPublicKey);
}
Parity::from_i32(pk_parity).map_err(Into::into)
let parity = Parity::from_i32(pk_parity)?;
Ok((self, parity))
}
}
@ -2048,23 +2073,27 @@ mod test {
#[test]
#[cfg(any(feature = "alloc", feature = "std"))]
fn test_tweak_add_assign_then_tweak_add_check() {
fn test_tweak_add_then_tweak_add_check() {
let s = Secp256k1::new();
// TODO: 10 times is arbitrary, we should test this a _lot_ of times.
for _ in 0..10 {
let tweak = Scalar::random();
let mut kp = KeyPair::new(&s, &mut thread_rng());
let (mut pk, _parity) = kp.x_only_public_key();
let kp = KeyPair::new(&s, &mut thread_rng());
let (xonly, _) = XOnlyPublicKey::from_keypair(&kp);
let orig_pk = pk;
kp.tweak_add_assign(&s, &tweak).expect("Tweak error");
let parity = pk.tweak_add_assign(&s, &tweak).expect("Tweak error");
let tweaked_kp = kp.add_xonly_tweak(&s, &tweak).expect("keypair tweak add failed");
let (tweaked_xonly, parity) = xonly.add_tweak(&s, &tweak).expect("xonly pubkey tweak failed");
let (back, _) = XOnlyPublicKey::from_keypair(&kp);
let (want_tweaked_xonly, tweaked_kp_parity) = XOnlyPublicKey::from_keypair(&tweaked_kp);
assert_eq!(back, pk);
assert!(orig_pk.tweak_add_check(&s, &pk, parity, tweak));
assert_eq!(tweaked_xonly, want_tweaked_xonly);
#[cfg(not(fuzzing))]
assert_eq!(parity, tweaked_kp_parity);
assert!(xonly.tweak_add_check(&s, &tweaked_xonly, parity, tweak));
}
}