[18686] in cryptography@c2.net mail archive
Re: SecurID and garage door openers
daemon@ATHENA.MIT.EDU (maf@appgate.com)
Tue Oct 18 15:42:42 2005
X-Original-To: cryptography@metzdowd.com
X-Original-To: cryptography@metzdowd.com
Date: Tue, 18 Oct 2005 21:17:40 +0200 (CEST)
From: maf@appgate.com
To: Greg Rose <ggr@qualcomm.com>
Cc: "Travis H." <solinym@gmail.com>, cryptography@metzdowd.com
In-Reply-To: <6.2.5.4.2.20051018091744.048bed20@qualcomm.com>
On 18 okt, Greg Rose wrote:
>>Similarly, how do those garage door openers with "rolling codes" work,
>>given that the user may have pressed the button many times
>>accidentally while out of range of the receiver?
>
> Ahh, one of the dirty little secrets. If the base receives two
> sequential outputs from a registered token, even if they are a long
> way away from the currently expected output, it will resynchronize to
> that.
I guess this varies. At least my former car had a warning in the manual,
regarding the remote, that it could get out of sync if I pressed the
buttons too many time while out of range. So I guess at least some
manufacturers did something a little bit better.
/MaF
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