[dm-crypt] benchmark, kernel, libgcrypt, comparisons

shmick at riseup.net shmick at riseup.net
Wed Jan 29 16:52:54 CET 2014

Milan Broz:
> On 01/29/2014 03:22 PM, shmick at riseup.net wrote:
>> i came across a text file benchmark i did with the 2nd latest cryptsetup
>> and thought id see how 1.6.3 would look
>> i have different kernel and libgcrpyt versions since 1.6.2 as well and
>> it was said on the gnupg list when libgcrypt 1.6.0 came out there were
>> some speed improvements
> In fact, gcrypt 1.6.0 was major slowdown for PBKDF2 (previously cryptsetup
> used own implementation because it was not available in gcrypt), but it will
> be fixed in gcrypt 1.6.1.
>> what would likely be the main source of speed increases - kernel or
>> libgcrypt ?
> In general, for hash algorithm used in header parsing or key derivation
> user space library is important (gcrypt), for block ciphers it is kernel.
> Usually in userspace openssl backend is faster, but gcrypt is default.

i compiled with openssl to see and hash algos were approx 2x 'speedier'
for me

> It is not much important because this is used only during device unlocking,
> data access later is pure kernel dm-crypt job.
>> serpent decryption is vastly faster, twofish in general but seems AES isn't
> This depends on machine (and which cipher implementation - it can be accelerated
> through AES-NI, SSE instruction etc, depends on your arch and kernel config).
> I think kernel API has continuous improvement, so check crypt modules available
> (dmcrypt will simply use what crypto API provides).
> Milan
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