AES256_GCM vs AES128_GCM

crypto_test.go

package crypto_test

import (
	"crypto/aes"
	"crypto/cipher"
	"crypto/rand"
	"io"
	"testing"
)

var (
	indata []byte
	key    []byte
)

func init() {
	indata = make([]byte, 128*1024)
	_, err := io.ReadFull(rand.Reader, indata)
	if err != nil {
		panic(err)
	}

	key = make([]byte, 32)
	_, err = io.ReadFull(rand.Reader, indata)
	if err != nil {
		panic(err)
	}
}

func benchmarkAES(key []byte, b *testing.B) {
	bc, err := aes.NewCipher(key)
	if err != nil {
		b.Fatal(err)
	}

	sc, err := cipher.NewGCM(bc)
	if err != nil {
		b.Fatal(err)
	}

	nonce := make([]byte, sc.NonceSize())
	_,err = io.ReadFull(rand.Reader, nonce)
	if err != nil {
		b.Fatal(err)
	}

	b.ResetTimer()

	var out []byte
	for i := 0; i < b.N; i++ {
		out = out[:0]
		out = sc.Seal(out, nonce, indata, nil)
	}

	b.SetBytes(int64(len(indata)))
}

func BenchmarkAES128(b *testing.B) {
	benchmarkAES(key[:16], b)
}

func BenchmarkAES256(b *testing.B) {
	benchmarkAES(key[:32], b)
}

// Darwin on 2.3GHz i7

jb@jborg-mbp:/crypto $ go version
go version devel +67f9ef140028 Sat Jul 12 15:18:36 2014 +1000 darwin/amd64
// that's Go1.3 + some
jb@jborg-mbp:/crypto $ go test -bench . -benchtime 5s
testing: warning: no tests to run
PASS
BenchmarkAES128 5000 1199331 ns/op 109.29 MB/s
BenchmarkAES256 5000 1281047 ns/op 102.32 MB/s
ok _/Users/jb/crypto 12.685s