bls12381: faster e6 MulBy01

Consensys · Mar 9, 2024 · 859ee92 · 859ee92
1 parent 444f06f
commit 859ee92
Showing 1 changed file with 4 additions and 3 deletions.
diff --git a/std/algebra/emulated/fields_bls12381/e6.go b/std/algebra/emulated/fields_bls12381/e6.go
@@ -216,9 +216,10 @@ func (e Ext6) MulBy01(z *E6, c0, c1 *E2) *E6 {
 	t0 = e.Ext2.Sub(t0, b)
 	t0 = e.Ext2.MulByNonResidue(t0)
 	t0 = e.Ext2.Add(t0, a)
-	tmp = e.Ext2.Add(&z.B0, &z.B2)
-	t2 := e.Ext2.Mul(c0, tmp)
-	t2 = e.Ext2.Sub(t2, a)
+	// for t2, schoolbook is faster than karatsuba
+	// c2 = a0b2 + a1b1 + a2b0,
+	// c2 = a2b0 + b ∵ b2 = 0, b = a1b1
+	t2 := e.Ext2.Mul(&z.B2, c0)
 	t2 = e.Ext2.Add(t2, b)
 	t1 := e.Ext2.Add(c0, c1)
 	tmp = e.Ext2.Add(&z.B0, &z.B1)