linux-kernel - Re: [PATCH 1/4] media: dvb/af9015, implement eeprom hashing

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: <4B5C76B8.4090700@gmail.com>
Date:	Sun, 24 Jan 2010 17:35:04 +0100
From:	Jiri Slaby <jirislaby@...il.com>
To:	Antti Palosaari <crope@....fi>
CC:	Jiri Slaby <jslaby@...e.cz>, linux-kernel@...r.kernel.org,
	Mauro Carvalho Chehab <mchehab@...hat.com>,
	linux-media@...r.kernel.org
Subject: Re: [PATCH 1/4] media: dvb/af9015, implement eeprom hashing

On 01/24/2010 05:16 PM, Antti Palosaari wrote:
>> +    af9015_config.eeprom_sum = 0;
>> +    for (reg = 0; reg<  eeprom_size / sizeof(u32); reg++) {
>> +        af9015_config.eeprom_sum *= GOLDEN_RATIO_PRIME_32;
>> +        af9015_config.eeprom_sum += le32_to_cpu(((u32 *)eeprom)[reg]);
>> +    }
>> +
>> +    deb_info("%s: eeprom sum=%.8x\n", __func__,
>> af9015_config.eeprom_sum);
> 
> Does this sum contain all 256 bytes from EEPROM? 256/4 is 64.

Yes it does. It is computed as a hashed sum of 32-bit numbers (4 bytes)
-- speed (does not matter) and larger space of hashes. Hence the
division by 4. The cast does the trick: ((u32 *)eeprom)[reg] -- reg
index is on a 4-byte basis.

regards,
-- 
js
--
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/