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Kabbone

Member

Registered: 2009-02-06

Posts: 31

LUKS & AES Instruction set

Hey,

I'm going to buy a new Netbook. The problem is, the cheap Intel processors (here: 1007U) don't have the AES feature, but the pure CPU-Power is quite more powerful than the E1-2500 from AMD which got the AES feature.
My question is, what do you think which one will have the better performance in the daily grind if the system is encrypted with LUKS AES?
Perhaps someone of you guys got an E1-2500 or E1-2100 at home and could deliver the results of

cryptsetup benchmark

Here a short view of the passmark results

Single Thread Rating
E1-2500   529
1007U     774

CPU Mark
E1-2500   918
1007U    1457

How could it be, that I got the following performance at my current Notebook (Core2Duo T7500)?

    aes-xts   256b   133.2 MiB/s   132.2 MiB/s
 serpent-xts   256b   144.9 MiB/s   151.4 MiB/s
 twofish-xts   256b   136.3 MiB/s   137.5 MiB/s
     aes-xts   512b   100.3 MiB/s    99.6 MiB/s
 serpent-xts   512b   145.6 MiB/s   151.9 MiB/s
 twofish-xts   512b   137.3 MiB/s   138.1 MiB/s

Shouldn't AES got the best performance and serpent the worst?

frostschutz

Member

Registered: 2013-11-15

Posts: 1,421

Re: LUKS & AES Instruction set

Some notebooks don't have AES-NI even though their CPUs support it (disabled by bios). Check /proc/cpuinfo if it has aes in the flags. Then check that your kernel supports it as well, aesni should be listed in /proc/crypto.

Kabbone

Member

Registered: 2009-02-06

Posts: 31

Re: LUKS & AES Instruction set

T7500 doesn't support it, but nevertheless should AES get a better performance than the other two, shouldn't it?

Last edited by Kabbone (2014-08-09 16:07:49)

frostschutz

Member

Registered: 2013-11-15

Posts: 1,421

Re: LUKS & AES Instruction set

Dunno. Apparently not, according to your benchmark. Although there are various modules for AES... a generic one, then intel assembler optimized, then aesni... speed varies depending on which is in use.

clfarron4

Member

From: London, UK

Registered: 2013-06-28

Posts: 2,163

Website

Re: LUKS & AES Instruction set

Shouldn't AES got the best performance and serpent the worst?

For encryption, I get that Serpent is the slowest, followed by AES and Twofish being the fastest on both my AMD 3305M APU and Intel i3-2370M.

For decryption, I get that AES is the slowest, followed by Serpent and Twofish being the fastest on both my AMD 3305M APU and Intel i3-2370M.

If you have an enabled working AES-NI processor, then I would expect AES to be fastest in both departments.

---

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Kabbone

Member

Registered: 2009-02-06

Posts: 31

Re: LUKS & AES Instruction set

Thanks for your replies. I just read, that AES is the easiest alghorithm of these three.

But what do you think how much the performance difference will be with and wihtout the AES-NI for such slow processors?

eazy

Member

From: London, UK

Registered: 2008-01-20

Posts: 97

Website

Re: LUKS & AES Instruction set

My post is probably useless to you, but I wanted to compare your results with my i5-2430M which has AES-NI enabled:

     aes-xts   256b  1501.5 MiB/s  1509.0 MiB/s
 serpent-xts   256b   243.2 MiB/s   247.5 MiB/s
 twofish-xts   256b   269.0 MiB/s   269.6 MiB/s
     aes-xts   512b  1165.1 MiB/s  1175.9 MiB/s
 serpent-xts   512b   258.1 MiB/s   247.2 MiB/s
 twofish-xts   512b   269.1 MiB/s   270.4 MiB/s

It's a faster processor than yours, so the 2x performance on Serpent and Twofish is expected, while I'm getting 10x with AES + AES-NI.

So yeah, if you want to enable LUKS+AES, get a processor with hardware encryption.

---

no masters to rule us, no gods to fool us

Kabbone

Member

Registered: 2009-02-06

Posts: 31

Re: LUKS & AES Instruction set

Thanks for your reply.
But finally I decided to take the 1007u without AES-NI, because it got much more power besides AES than the E1-2500 which was the only real competitor in this priceclass. Obviously my SSD suffers under the CPU bottleneck now.
Here the benchmarks for the 1007u + OCZ Vector 128GB

     aes-xts   256b   104.0 MiB/s   103.0 MiB/s
 serpent-xts   256b   120.0 MiB/s   113.3 MiB/s
 twofish-xts   256b   100.6 MiB/s   100.3 MiB/s
     aes-xts   512b    78.6 MiB/s    77.5 MiB/s
 serpent-xts   512b   120.3 MiB/s   113.6 MiB/s
 twofish-xts   512b   100.6 MiB/s   100.1 MiB/s