[60201] in cryptography@c2.net mail archive
Re: Can you keep a secret? This encrypted drive can...
daemon@ATHENA.MIT.EDU (Jason Holt)
Mon Nov 6 17:32:58 2006
X-Original-To: cryptography@metzdowd.com
X-Original-To: cryptography@metzdowd.com
Date: Mon, 6 Nov 2006 18:47:57 +0000 (UTC)
From: Jason Holt <jason@lunkwill.org>
To: Ralf Senderek <ralf@senderek.com>
Cc: cryptography@metzdowd.com
In-Reply-To: <Pine.LNX.4.63.0611041034120.2896@lions.kerry-linux.ie>
On Sat, 4 Nov 2006, Ralf Senderek wrote:
> On the unencrypted filesystem:
>
> # > time dd if=/dev/zero of=cryptogram bs=1MB count=50
> 50+0 records in
> 50+0 records out
> 50000000 bytes (50 MB) copied, 0.216106 seconds, 231 MB/s
>
> real 0m0.257s
> user 0m0.000s
> sys 0m0.252s
Unless you have a disk array in your laptop, that performance is an artifact
of buffering. Here are unbuffered and buffered numbers for my rather new
desktop machine:
$ hdparm -t /dev/sda
/dev/sda:
Timing buffered disk reads: 174 MB in 3.01 seconds = 57.79 MB/sec
$ hdparm -T /dev/sda
/dev/sda:
Timing cached reads: 5188 MB in 2.00 seconds = 2595.82 MB/sec
The 25MB/sec number for your encrypted partition looks like it's probably
right, though:
$ openssl speed aes-256-cbc
[...]
The 'numbers' are in 1000s of bytes per second processed.
type 16 bytes 64 bytes 256 bytes 1024 bytes 8192 bytes
aes-256 cbc 52071.66k 55008.98k 55609.83k 55984.13k 55776.36k
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