Why SHA1 is slower than AES? JCE

Question

I'm currently building applications, which uses crypto primitives. For encryption and hashing I use javax.crypto and java.security packages. I did some benchmarking and it turned out, that ECB-AES-128 is faster than SHA1. Code that I used for AES testing:

    byte[] key = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
    byte[] data = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};

    SecretKeySpec encryptionKey = new SecretKeySpec(key, "AES");
    Cipher cipher = Cipher.getInstance("AES/ECB/NoPadding");
    cipher.init(Cipher.ENCRYPT_MODE, encryptionKey);

    long start = System.currentTimeMillis();
    for (int i=0; i<10000000; i++)
    {
        cipher.doFinal(data);
    }
    long end = System.currentTimeMillis();      

    System.out.println("took: "+ (end-start));

For hashing

    MessageDigest md = MessageDigest.getInstance("SHA-1");
    byte[] data = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};


    long start = System.currentTimeMillis();
    for (int i=0; i<10000000; i++)
    {
        md.digest(data);
    }
    long end = System.currentTimeMillis();

    System.out.println("took:" + (end-start));

Encryption time takes : ~4sec. Hashing time takes: ~10sec. Config: Core i5 3570-3.4Ghz, 8Gb RAM (not sure , whether it matters)

Why encryption takes less time than hashing? Hash functions should be way faster. Am I doing something wrong? Thank you

First of all, what does it matter? You use both of them for different purposes. Could you try with `-client` and see what happens? If that doesn't make a difference, I may have some other things that may be of influence. — Maarten Bodewes, Oct 21 '14 at 20:43
The main goal of a cryptographic hash is security not speed. In fact it helps security if it is not too fast because an attacker would need more time to execute it on many different inputs. — Henry, Oct 21 '14 at 20:43
@Henry Note that a normal hash function has a different purpose than a password hash function. For those functions a PBKDF is usually used. Those "password hashing" functions need to be slow, not the underlying hash (if any)! — Maarten Bodewes, Oct 21 '14 at 21:15
@owlstead I agree that being slow is much more important for password hashes. Still, finding collisions by brute force is less work if the hash function is faster. — Henry, Oct 21 '14 at 21:33
@Henry If function range is 256 bit , brute force is the waste of thousands of years even with super fast hash function — Sparrow_ua, Oct 21 '14 at 21:38
@Henry Speed has always been one of the main reasons why hash functions are chosen in the first place - after security of course. Check out the SHA-3 competition to understand what I'm talking about. You can always iterate over them N times such as in PBKDF2 if you want to slow them down. Note that slower hash functions are a poor choice for a PBKDF2 because an attacker has more chance of creating a fast hardware implementation. — Maarten Bodewes, Oct 21 '14 at 22:24

score 0 · Accepted Answer · answered Oct 21 '14 at 21:05

Please find the results for openssl speed sha1 aes-128-cbc below:

The 'numbers' are in 1000s of bytes per second processed.
type             16 bytes     64 bytes    256 bytes   1024 bytes   8192 bytes
sha1             27821.86k    81142.78k   181461.85k   272193.19k   312980.82k
aes-128 cbc      55984.60k    63748.01k    64728.23k   104889.11k   107399.85k

As you can see AES is faster for smaller amounts, and slower for large amounts. Why does this happen? Well, simple. AES uses a block size of 128 bits while SHA-1 uses a block size of 512 bits. So for small amounts of data, SHA-1 has to do much more work. Note that for 64 bytes, SHA-1 has to use 2 full blocks, so it is still rather at a disadvantage. Because of the bigger state size, I expect it will also optimize less easily.

AES is usually also heavily optimized. I'm not sure that SHA-1 in Java has seen the same amount of interest. Nowadays, you would rather look at SHA-2.

I definitely forgot about padding. I do care about efficiency as well. SHA-1 provides acceptable security for my purposes. I checked other benchmarks, where http://www.cryptopp.com/benchmarks.html — Sparrow_ua, Oct 21 '14 at 21:12

Why SHA1 is slower than AES? JCE

1 Answers1