Add Python binding to scalar_multiply

crates/chia-bls/Cargo.toml

@@ -12,7 +12,7 @@ repository = "https://github.com/Chia-Network/chia_rs"
 workspace = true
 
 [features]
-py-bindings = ["dep:pyo3", "chia_py_streamable_macro", "chia-traits/py-bindings"]
+py-bindings = ["dep:pyo3", "dep:num-bigint", "chia_py_streamable_macro", "chia-traits/py-bindings"]
 arbitrary = ["dep:arbitrary"]
 
 [dependencies]
@@ -24,9 +24,10 @@ hkdf = { workspace = true }
 blst = { workspace = true }
 hex = { workspace = true }
 thiserror = { workspace = true }
-pyo3 = { workspace = true, features = ["multiple-pymethods"], optional = true }
+pyo3 = { workspace = true, features = ["multiple-pymethods", "num-bigint"], optional = true }
 arbitrary = { workspace = true, optional = true }
 lru = { workspace = true }
+num-bigint = { workspace = true, optional = true }
 
 [dev-dependencies]
 rand = { workspace = true }

crates/chia-bls/src/public_key.rs

@@ -296,6 +296,9 @@ pub fn hash_to_g1_with_dst(msg: &[u8], dst: &[u8]) -> PublicKey {
     PublicKey(p1)
 }
 
+#[cfg(feature = "py-bindings")]
+use num_bigint::BigInt;
+
 #[cfg(feature = "py-bindings")]
 #[pyo3::pymethods]
 impl PublicKey {
@@ -340,6 +343,16 @@ impl PublicKey {
     pub fn __iadd__(&mut self, rhs: &Self) {
         *self += rhs;
     }
+
+    #[must_use]
+    #[pyo3(name = "scalar_multiply")]
+    #[allow(clippy::needless_pass_by_value)]
+    pub fn py_scalar_multiply(&self, scalar: BigInt) -> Self {
+        let mut clone = *self;
+        let bytes = scalar.to_signed_bytes_be();
+        clone.scalar_multiply(&bytes);
+        clone
+    }
 }
 
 #[cfg(feature = "py-bindings")]

crates/chia-bls/src/signature.rs

@@ -475,6 +475,9 @@ pub fn sign<Msg: AsRef<[u8]>>(sk: &SecretKey, msg: Msg) -> Signature {
     sign_raw(sk, aug_msg)
 }
 
+#[cfg(feature = "py-bindings")]
+use num_bigint::BigInt;
+
 #[cfg(feature = "py-bindings")]
 #[pyo3::pymethods]
 impl Signature {
@@ -509,6 +512,16 @@ impl Signature {
     pub fn __iadd__(&mut self, rhs: &Self) {
         *self += rhs;
     }
+
+    #[must_use]
+    #[pyo3(name = "scalar_multiply")]
+    #[allow(clippy::needless_pass_by_value)]
+    pub fn py_scalar_multiply(&self, scalar: BigInt) -> Self {
+        let mut clone = self.clone();
+        let bytes = scalar.to_signed_bytes_be();
+        clone.scalar_multiply(&bytes);
+        clone
+    }
 }
 
 #[cfg(feature = "py-bindings")]
@@ -1203,6 +1216,27 @@ mod tests {
         }
     }
 
+    #[test]
+    fn test_scalar_multiply_large() {
+        let mut rng = StdRng::seed_from_u64(1337);
+        let mut data = [0; 4198];
+        rng.fill(data.as_mut_slice());
+        let seed: [u8; 32] = rng.gen();
+        let msg: [u8; 32] = rng.gen();
+        let sk = SecretKey::from_seed(&seed);
+        let mut g2 = sign(&sk, msg);
+        g2.scalar_multiply(&data);
+        assert_eq!(
+            hex::encode(g2.to_bytes()),
+            "
+            ae4d384a25c51283b8be8c6546d23e1555995c87fbcc0fe12169b63a052c4a1f
+            c9d3a020e8e010d4be619e3c0980a1f213b951fe75375012c5df6a690548a637
+            ef25f8da1e4f9c8f4d2062531ce688c040258a76543831abde774872e00af74b
+            "
+            .replace([' ', '\n'], "")
+        );
+    }
+
     #[test]
     fn test_hash_to_g2_different_dst() {
         const DEFAULT_DST: &[u8] = b"BLS_SIG_BLS12381G2_XMD:SHA-256_SSWU_RO_AUG_";

wheel/generate_type_stubs.py

@@ -389,6 +389,7 @@ def __init__(
             "def __add__(self, other: G1Element) -> G1Element: ...",
             "def __iadd__(self, other: G1Element) -> G1Element: ...",
             "def derive_unhardened(self, int) -> G1Element: ...",
+            "def scalar_multiply(self, value: int) -> G1Element: ...",
         ],
     )
     print_class(
@@ -404,6 +405,7 @@ def __init__(
             "def __str__(self) -> str: ...",
             "def __add__(self, other: G2Element) -> G2Element: ...",
             "def __iadd__(self, other: G2Element) -> G2Element: ...",
+            "def scalar_multiply(self, value: int) -> G2Element: ...",
         ],
     )
     print_class(

wheel/python/chia_rs/chia_rs.pyi

@@ -158,6 +158,7 @@ class G2Element:
     def __str__(self) -> str: ...
     def __add__(self, other: G2Element) -> G2Element: ...
     def __iadd__(self, other: G2Element) -> G2Element: ...
+    def scalar_multiply(self, value: int) -> G2Element: ...
     def __init__(
         self
     ) -> None: ...