add g1_multi_exp

specs/deneb/polynomial-commitments.md

@@ -277,9 +277,10 @@ def g1_lincomb(points: Sequence[KZGCommitment], scalars: Sequence[BLSFieldElemen
     BLS multiscalar multiplication. This function can be optimized using Pippenger's algorithm and variants.
     """
     assert len(points) == len(scalars)
-    result = bls.Z1()
-    for x, a in zip(points, scalars):
-        result = bls.add(result, bls.multiply(bls.bytes48_to_G1(x), a))
+    points_g1 = []
+    for point in points:
+        points_g1.append(bls.bytes48_to_G1(point))
+    result = bls.g1_multi_exp(points_g1,scalars)
     return KZGCommitment(bls.G1_to_bytes48(result))
 ```
 

tests/core/pyspec/eth2spec/utils/bls.py

@@ -224,6 +224,23 @@ def multiply(point, scalar):
         return point * scalar
     return py_ecc_mul(point, scalar)
 
+def g1_multi_exp(points, integers):
+    """
+    Performs a multi-scalar multiplication between
+    `points` and `scalars`.
+    `point` should be in G1
+    """
+    assert(len(points) == len(integers))
+    if bls == arkworks_bls or bls == fastest_bls:
+        scalars = []
+        for integer in integers:
+            int_as_bytes = integer.to_bytes(32, 'little')
+            scalars.append(arkworks_Scalar.from_le_bytes(int_as_bytes))
+        return arkworks_G1.multiexp_unchecked(points, scalars)
+    result = Z1()
+    for point,scalar in points.zip(scalars):
+        result = add(result, multiply(point, scalar))
+    return result
 
 def neg(point):
     """