CWvb17eB

1import javax.crypto.Cipher;
2import javax.crypto.KeyGenerator;
3import javax.crypto.SecretKey;
4import javax.crypto.spec.GCMParameterSpec;
5import javax.crypto.spec.IvParameterSpec;
6import java.security.SecureRandom;
7
8public class AES_Mode_Speed {
9    // AES parameters
10    private static final int AES_KEY_SIZE = 128; // in bits
11    private static final int AES_COUNTER_SIZE = 16; // in bytes
12    private static final int GCM_NONCE_LENGTH = 12; // in bytes. 12 is the recommended value.
13    private static final int GCM_TAG_LENGTH = 16 * 8; // in bits
14
15    public static void main(String[] args) throws Exception {
16        SecureRandom sr = new SecureRandom();
17
18        KeyGenerator kg = KeyGenerator.getInstance("AES");
19        kg.init(AES_KEY_SIZE);
20        SecretKey key = kg.generateKey();
21
22        byte[] counter = new byte[AES_COUNTER_SIZE];
23        sr.nextBytes(counter);
24        IvParameterSpec ips = new IvParameterSpec(counter);
25        Cipher aes_ctr = Cipher.getInstance("AES/CTR/NoPadding");
26        aes_ctr.init(Cipher.ENCRYPT_MODE, key, ips);
27
28
29        byte[] nonce = new byte[GCM_NONCE_LENGTH];
30        sr.nextBytes(nonce);
31        GCMParameterSpec gps = new GCMParameterSpec(GCM_TAG_LENGTH, nonce);
32        Cipher aes_gcm = Cipher.getInstance("AES/GCM/NoPadding");
33        aes_gcm.init(Cipher.ENCRYPT_MODE, key, gps);
34
35        speedTest(aes_ctr);
36        speedTest(aes_gcm);
37    }
38
39    private static void speedTest(Cipher cipher) throws Exception {
40        byte[] ptxt = new byte[1 << 26];
41        long start, end;
42
43        start = System.nanoTime();
44        cipher.doFinal(ptxt);
45        end = System.nanoTime();
46
47
48        System.out.printf("%s took %f seconds.n",
49                cipher.getAlgorithm(),
50                (end - start) / 1E9);
51    }
52}
53	
54AES/CTR/NoPadding took 0.237487 seconds.
55AES/GCM/NoPadding took 1.014950 seconds.
56	
57The 'numbers' are in 1000s of bytes per second processed.
58type             16 bytes     64 bytes    256 bytes   1024 bytes   8192 bytes  16384 bytes
59aes-128-ctr     463059.16k  1446320.32k  3515070.12k  5182218.92k  6063797.59k  6210150.19k
60aes-128-gcm     480296.99k  1088337.47k  2531854.17k  4501395.11k  5940079.27k  6087589.89k