TestHMACTotalTiming.go

func TestHMACTotalTiming(t *testing.T) {
	sumData := make(plotter.XYs, 256)
	constData := make(plotter.XYs, 256)
	naiveData := make(plotter.XYs, 256)

	data := []byte("0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789")
	sumBuf := make([]byte, 0, 100)
	for n := 0; n < 256; n++ {
		var res1, res2 []byte
		ns := testing.Benchmark(func(b *testing.B) {
			h := hmac.New(newConstantTimeHash(sha1.New), make([]byte, 30))
			for i := 0; i < b.N; i++ {
				h.Reset()
				h.Write(data[:len(data)-n])
				res1 = h.Sum(sumBuf)
				h.Write(data[len(data)-n:])
			}
		}).NsPerOp()
		t.Logf("ConstantTimeHash %d bytes: %d ns/op", n, ns)
		constData[n].X = float64(len(data) - n)
		constData[n].Y = float64(ns)

		ns = testing.Benchmark(func(b *testing.B) {
			h := hmac.New(sha1.New, make([]byte, 30))
			for i := 0; i < b.N; i++ {
				h.Reset()
				h.Write(data[:len(data)-n])
				res2 = h.Sum(sumBuf)
			}
		}).NsPerOp()
		t.Logf("Sum %d bytes: %d ns/op", n, ns)
		sumData[n].X = float64(len(data) - n)
		sumData[n].Y = float64(ns)

		ns = testing.Benchmark(func(b *testing.B) {
			h := hmac.New(sha1.New, make([]byte, 30))
			for i := 0; i < b.N; i++ {
				h.Reset()
				h.Write(data[:len(data)-n])
				res2 = h.Sum(sumBuf)
				h.Write(data[len(data)-n:])
			}
		}).NsPerOp()
		t.Logf("Sum+Write %d bytes: %d ns/op", n, ns)
		naiveData[n].X = float64(len(data) - n)
		naiveData[n].Y = float64(ns)

		if !bytes.Equal(res1, res2) {
			t.Errorf("different output at length %d", n)
		}
	}

	p, err := plot.New()
	if err != nil {
		panic(err)
	}
	p.Title.Text = "HMAC timings"
	p.X.Label.Text = "First Write() bytes"
	p.Y.Label.Text = "ns"

	s, err := plotter.NewScatter(sumData)
	if err != nil {
		panic(err)
	}
	c, err := plotter.NewScatter(constData)
	if err != nil {
		panic(err)
	}
	c.GlyphStyle.Shape = draw.PyramidGlyph{}
	c.GlyphStyle.Color = color.RGBA{R: 255, A: 255}
	x, err := plotter.NewScatter(naiveData)
	if err != nil {
		panic(err)
	}
	x.GlyphStyle.Shape = draw.CrossGlyph{}
	x.GlyphStyle.Color = color.RGBA{R: 255, A: 255}
	p.Add(s, c, x)

	if err := p.Save(297*vg.Millimeter, 210*vg.Millimeter, "hmac.png"); err != nil {
		panic(err)
	}
}