[clug] how long to encrypt a 1T exernal disk using LUKS

Daniel Pittman daniel at rimspace.net
Sun Jun 27 22:22:28 MDT 2010

steve jenkin <sjenkin at canb.auug.org.au> writes:
> jhock wrote on 28/06/10 8:35 AM:
>> I have an eeepc 10HD with Ubuntu 10.0 and Western Digital 1 terabyte
>> external hard disk. I started encrypting the WD disk yesterday using
>> gdecrypt and luks. Does anyone know how long this could take. It is
>> still encrypting this morning. So far top tells me the kcrypt command
>> has been running for "1075:00". I expect that it minutes.
> A useful benchmark for crypto performance is ssh/scp.

It is?

> [Which is RSA/DSA to start, then uses lighter symmetric keys, IIRC]

All sane people and protocols do, both because asymmetric encryption is so
slow, and because it is so relatively weak compared to symmetric

> I've rarely seen anything that pushes 100Mbps (~10MB/s).

Relatively modest, old hardware can comfortably hit that target; my old core2
2.6GHz system can manage a flat 125 megabytes (yes, *bytes*) a second of
AES-256-IGE 8K blocks, and 138 of AES-256-CBC 8K blocks.  On a single core.

> Without evidence/knowledge, I'm going to guess the Atom does crypto like
> a SPARC 300Mhz: ~10Mbps (1MB/sec == 3.5Gb/hour == 200-300 Hrs/Tb)

About one sixth the speed of my core2 machine, IIRC, so around 20MB a second
or so for large-block encryption.  Roughly.


[1]  See also 1K key lengths being weak in asymmetric encryption now, while
     256 bit symmetric keys remain strong.

✣ Daniel Pittman            ✉ daniel at rimspace.net            ☎ +61 401 155 707
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