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Date: Wed, 9 Oct 2013 00:47:38 -0700
From: Alex Gaynor <>
Subject: Re: Source of bad password hashing practices? MySQL manual...

Nope, this is not correct either. You do not want to use a hashing function
on a password, you want to use a key derivation function, which have
entirely different properties from hashing functions. Most notably, hashing
functions are typically designed to execute quickly, while KDFs are
actually designed to be hard to implement quickly.


On Wed, Oct 9, 2013 at 12:45 AM, <> wrote:

> On 08-Oct-2013 19:57:52 -0400, Rich Felker wrote:
>  > It's come to my attention recently that the MySQL reference
>  > manual is recommending very poor password hashing practices
>  > as part of its security guidelines:
>  > "Do not store cleartext passwords in your database.
> This is primary and undoubtedly correct recommendation.
>  > If your computer becomes compromised, the intruder can take
>  > the full list of passwords and use them.
> True.
>  > Instead, use SHA2(), SHA1(), MD5(), or some other one-way
>  > hashing function and store the hash value."
> Well, hashing functions may be reverted using rainbow tables, but
> even this simple recommendation pushes web developers to think
> about their sites' security.
>  > (
> This document is destined for people who never cared of security,
> so I'd suggest only one addition:
> "To prevent password recovery using the rainbow tables, don't use
> these functions on a plain password; instead, choose some string
> to be used as a salt, and use hash(hash(password)+salt) values."
>  > With MySQL being one of the major traditional "LAMP stack"
>  > components, I wonder if this is the source from which many
>  > web developers are getting their ideas on how to do password
>  > hashing. What is the proper procedure for publicizing
>  > documentation bugs like this which are leading to poor
>  > security practice, and for getting them fixed?
> This is not a bug, this is incompleteness. Minor one, I'd say...
> --
> Alexey V. Vissarionov aka Gremlin from Kremlin <gremlin ПРИ gremlin ТЧК ru>
> GPG: 8832FE9FA791F7968AC96E4E909DAC45EF3B1FA8 @ hkp://

"I disapprove of what you say, but I will defend to the death your right to
say it." -- Evelyn Beatrice Hall (summarizing Voltaire)
"The people's good is the highest law." -- Cicero
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