Add initial nistec project files

p256_test.go

@@ -0,0 +1,49 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build (!amd64 && !arm64 && !ppc64le && !s390x) || purego
+
+package nistec
+
+import (
+	"bytes"
+	"fmt"
+	"testing"
+
+	"sources.truenas.cloud/code/nistec/internal/fiat"
+)
+
+func TestP256PrecomputedTable(t *testing.T) {
+	base := NewP256Point().SetGenerator()
+
+	for i := 0; i < 43; i++ {
+		t.Run(fmt.Sprintf("table[%d]", i), func(t *testing.T) {
+			testP256AffineTable(t, base, &p256GeneratorTables[i])
+		})
+
+		for k := 0; k < 6; k++ {
+			base.Double(base)
+		}
+	}
+}
+
+func testP256AffineTable(t *testing.T, base *P256Point, table *p256AffineTable) {
+	p := NewP256Point()
+	zInv := new(fiat.P256Element)
+
+	for j := 0; j < 32; j++ {
+		p.Add(p, base)
+
+		// Convert p to affine coordinates.
+		zInv.Invert(&p.z)
+		p.x.Mul(&p.x, zInv)
+		p.y.Mul(&p.y, zInv)
+		p.z.One()
+
+		if !bytes.Equal(table[j].x.Bytes(), p.x.Bytes()) ||
+			!bytes.Equal(table[j].y.Bytes(), p.y.Bytes()) {
+			t.Fatalf("incorrect table entry at index %d", j)
+		}
+	}
+}