linux-kernel - Re: [PATCH] Make efi-pstore return a unique id

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <52740A3A.70202@nod.at>
Date:	Fri, 01 Nov 2013 21:08:26 +0100
From:	Richard Weinberger <richard@....at>
To:	Seiji Aguchi <seiji.aguchi@....com>
CC:	Tony Luck <tony.luck@...il.com>, Madper Xie <cxie@...hat.com>,
	"matt.fleming@...el.com" <matt.fleming@...el.com>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Linux EFI <linux-efi@...r.kernel.org>,
	谢成骏 <bbboson@...il.com>
Subject: Re: [PATCH] Make efi-pstore return a unique id

Am 01.11.2013 20:22, schrieb Seiji Aguchi:
>>>> +{
>>>> +       char id_str[64];
>>>> +       u64 id = 0;
>>>> +
>>>> +       sprintf(id_str, "%lu%u%d", timestamp, part, count);
>>>> +       if (kstrtoull(id_str, 10, &id))
>>>> +               pr_warn("efi-pstore: failed to generate id\n");
>>>> +       return id;
>>>> +}
>>>
>>> This is just odd. You make a string from three ints and then a parse
>>> it to a int again.
>>
>> Agreed.  I liked your ((timestamp * 100 + part) * 100 + count function much
>> more than this.
> 
> I was worried that the part and count could be more than 100.
> If it happens, the id may not be unique...
> 
> But, currently, size of nvram storage is limited, so it is a corner case.
> I respect your opinion.

What about feeding the bytes of all three integers into a non-cryptographic hash function?
Using this way you get a cheap unique id.

Thanks,
//richard
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/